deforest

explanation blue bibcodes open ADS page with paths to full text

Author name code: deforest
ADS astronomy entries on 2022-09-14
author:"DeForest, Craig"

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Title: Defining the Middle Corona
Authors: West, Matthew J.; Seaton, Daniel B.; Wexler, David B.;
Raymond, John C.; Del Zanna, Giulio; Rivera, Yeimy J.; Kobelski,
Adam R.; DeForest, Craig; Golub, Leon; Caspi, Amir; Gilly, Chris R.;
Kooi, Jason E.; Alterman, Benjamin L.; Alzate, Nathalia; Banerjee,
Dipankar; Berghmans, David; Chen, Bin; Chitta, Lakshmi Pradeep; Downs,
Cooper; Giordano, Silvio; Higginson, Aleida; Howard, Russel A.; Mason,
Emily; Mason, James P.; Meyer, Karen A.; Nykyri, Katariina; Rachmeler,
Laurel; Reardon, Kevin P.; Reeves, Katharine K.; Savage, Sabrina;
Thompson, Barbara J.; Van Kooten, Samuel J.; Viall, Nicholeen M.;
Vourlidas, Angelos
2022arXiv220804485W Altcode:
The middle corona, the region roughly spanning heliocentric altitudes
from $1.5$ to $6\,R_\odot$, encompasses almost all of the influential
physical transitions and processes that govern the behavior of
coronal outflow into the heliosphere. Eruptions that could disrupt
the near-Earth environment propagate through it. Importantly, it
modulates inflow from above that can drive dynamic changes at lower
heights in the inner corona. Consequently, this region is essential
for comprehensively connecting the corona to the heliosphere and for
developing corresponding global models. Nonetheless, because it is
challenging to observe, the middle corona has been poorly studied by
major solar remote sensing missions and instruments, extending back to
the Solar and Heliospheric Observatory (SoHO) era. Thanks to recent
advances in instrumentation, observational processing techniques,
and a realization of the importance of the region, interest in the
middle corona has increased. Although the region cannot be intrinsically
separated from other regions of the solar atmosphere, there has emerged
a need to define the region in terms of its location and extension
in the solar atmosphere, its composition, the physical transitions
it covers, and the underlying physics believed to be encapsulated by
the region. This paper aims to define the middle corona and give an
overview of the processes that occur there.

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Title: Square Root Compression and Noise Effects in Digitally
Transformed Images
Authors: DeForest, Craig E.; Lowder, Chris; Seaton, Daniel B.; West,
Matthew J.
2022ApJ...934..179D Altcode: 2022arXiv220705601D
We report on a particular example of noise and data representation
interacting to introduce systematic error into scientific
measurements. Many instruments collect integer digitized values and
apply nonlinear coding, in particular square root coding, to compress
the data for transfer or downlink; this can introduce surprising
systematic errors when they are decoded for analysis. Square root
coding and subsequent decoding typically introduces a variable ±1 count
value-dependent systematic bias in the data after reconstitution. This
is significant when large numbers of measurements (e.g., image pixels)
are averaged together. Using direct modeling of the probability
distribution of particular coded values in the presence of instrument
noise, one may apply Bayes' theorem to construct a decoding table that
reduces this error source to a very small fraction of a digitizer step;
in our example, systematic error from square root coding is reduced
by a factor of 20 from 0.23 to 0.012 count rms. The method is suitable
both for new experiments such as the upcoming PUNCH mission, and also
for post facto application to existing data sets-even if the instrument
noise properties are only loosely known. Further, the method does not
depend on the specifics of the coding formula, and may be applied to
other forms of nonlinear coding or representation of data values.

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Title: Tracing the Drivers of Slow Solar Wind in the Middle Corona
Authors: Chitta, Lakshmi Pradeep; DeForest, Craig; Downs, Cooper;
Seaton, Daniel; Higginson, Aleida
2022cosp...44.1328C Altcode:
Compared to the so-called fast solar wind that originates from polar
coronal holes during the solar minimum, low-latitude wind streams
generally have lower speeds ($\le$ 500 km/s). These slow solar wind
streams closer to the ecliptic plane are characterised by their high
spatial structuring, temporal variability, and coronal compositions. The
magnetic driver responsible for the origin of this slow solar wind
and its characteristics, however, is a subject of active debate. Using
coronal observations from the 2018 off-pointing campaign of the GOES
Solar Ultraviolet Imager (SUVI) as well as images from SOHO/LASCO, we
found signatures of solar wind streams driven by magnetic reconnection
in the highly structured middle corona. In particular, elongated
coronal loops in the middle corona over a coronal-hole-active-region
complex are observed to reconnect and retract while in the process,
some plasma is propelled away from the Sun as streams or blobs. Using
STEREO observations we found that similar streams forming over the
same complex escape into the heliosphere. In this talk, we will
present these new results and discuss them in the context of models
of slow solar wind sources and drivers. our findings emphasise the
key necessity of having routine extreme ultraviolet observations of
the middle coronal processes from ecliptic and polar vantage points,
along with extended coronal diagnostics to develop better understanding
of the heliospheric impact of Sun's activity.

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Title: Exploring Structures and Flows with NASA's under-construction
PUNCH mission
Authors: DeForest, Craig; Gibson, Sarah; Thompson, Barbara;
Malanushenko, Anna; Desai, Mihir; Elliott, Heather; Viall, Nicholeen;
Cranmer, Steven; de Koning, Curt
2022cosp...44.1077D Altcode:
The Polarimeter to UNify the Corona and Heliosphere is a NASA Small
Explorer to image the corona and heliosphere as parts of a single
system. PUNCH comprises four ~50kg smallsats, each carrying one imaging
instrument, that work together to form a single "virtual coronagraph"
with a 90° field of view, centered on the Sun. Scheduled for joint
launch with NASA's SPHEREx mission, PUNCH starts its two-year prime
science phase in 2025. PUNCH will generate full polarized image
sequences of Thomson-scattered light from free electrons in the corona
and young solar wind, once every four minutes continuously. This
enables tracking the young solar wind and turbulent structures within
it as they disconnect from the Sun itself, as well as large transients
such as CMEs, CIRs, and other shocks within the young solar wind. A
student-contributed X-ray spectrometer (STEAM) will address questions
of coronal heating and flare physics. We present motivating science,
expected advances, mission status, and how to get involved with PUNCH
science now.

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Title: Expected results for the cradle of the Solar Wind with the
Polarimeter to UNify the Corona and Heliosphere (PUNCH)
Authors: DeForest, Craig; Gibson, Sarah; De Koning, Curt A.; Thompson,
Barbara; Malanushenko, Anna; Desai, Mihir; Elliott, Heather; Viall,
Nicholeen; Cranmer, Steven
2022cosp...44.1324D Altcode:
The Polarimeter to UNify the Corona and Heliosphere is a NASA Small
Explorer to image the corona and heliosphere as parts of a single
system. Imaging the corona and heliosphere together from a constellation
of four synchronized smallsats, PUNCH will — starting in 2025 —
provide a unique window on global structure and cross-scale processes
in the outer corona and young solar wind. PUNCH science is informed
by, and complements, the results of PSP and Solar Orbiter; and will
synergize with PROBA3/ASPIICS. We present early prototype results from
STEREO/SECCHI and current preparation work to enable PUNCH science
when data arrive, discuss anticipated results from the deeper-field,
higher time resolution imaging that PUNCH will provide, and describe
how to get involved with PUNCH science now.

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Title: Quasi-periodic Energy Release and Jets at the Base of Solar
Coronal Plumes
Authors: Kumar, Pankaj; Karpen, Judith T.; Uritsky, Vadim M.; Deforest,
Craig E.; Raouafi, Nour E.; Richard DeVore, C.
2022ApJ...933...21K Altcode: 2022arXiv220413871K
Coronal plumes are long, ray-like, open structures that have been
considered as possible sources of the solar wind. Their origin in
the largely unipolar coronal holes has long been a mystery. Earlier
spectroscopic and imaging observations revealed blueshifted plasma and
propagating disturbances (PDs) in plumes that are widely interpreted
in terms of flows and/or propagating slow-mode waves, but these
interpretations (flows versus waves) remain under debate. Recently we
discovered an important clue about plume internal structure: dynamic
filamentary features called plumelets, which account for most of the
plume emission. Here we present high-resolution observations from
the Solar Dynamics Observatory/Atmospheric Imaging Assembly and
the Interface Region Imaging Spectrograph that revealed numerous,
quasi-periodic, tiny jets (so-called jetlets) associated with
transient brightening, flows, and plasma heating at the chromospheric
footpoints of the plumelets. By analogy to larger coronal jets,
these jetlets are most likely produced within the plume base by
magnetic reconnection between closed and open flux at stressed 3D
null points. The jetlet-associated brightenings are in phase with
plumelet-associated PDs, and vary with a period of ~3-5 minutes, which
is remarkably consistent with the photospheric/chromospheric p-mode
oscillation. This reconnection at the open-closed boundary in the
chromosphere/transition region is likely modulated or driven by local
manifestations of the global p-mode waves. The jetlets extend upward
to become plumelets, contribute mass to the solar wind, and may be
sources of the switchbacks recently detected by the Parker Solar Probe.

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Title: Remote Sensing of Turbulence and Solar Wind Structure with
the PUNCH mission
Authors: DeForest, Craig; Gibson, Sarah; Matthaeus, William; Viall,
Nicholeen
2022cosp...44.1212D Altcode:
The Polarimeter to UNify the Corona and Heliosphere is a mission to
observe the corona and the inner heliosphere as a unified system. PUNCH
will produce continuous images of the solar wind and corona between
1.5° and 45° from the Sun, over a two year prime science mission
scheduled to start in early 2025. PUNCH uses visible sunlight scattered
by free electrons in the corona, to track density structures in the
corona and solar wind. We will describe PUNCH's unique 3D imaging
capability, mission structure, and anticipated results measuring the
development of large-scale turbulence, and the large- and meso-scale
structure of the solar wind itself.

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Title: Bayesian analysis of square-rooted values
Authors: DeForest, C. E.; Lowder, C.; Seaton, D. B.; West, M. J.
2022zndo...6672640D Altcode:
This is a pair of Jupyter notebooks developing a
second-order-approximation square root decoder, using a Bayesian
approach to interpreting detector values. The square root decoder
improves residual error from ~0.24DN RMS to ~0.013DN RMS in a typical
application. The Jupyter format allows reproduction and numerical
experiment for other applications. One notebook shows the method's
derivation and verification; the other shows application to a particular
data set.

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Title: The Coronal Veil
Authors: Malanushenko, A.; Cheung, M. C. M.; DeForest, C. E.; Klimchuk,
J. A.; Rempel, M.
2022ApJ...927....1M Altcode: 2021arXiv210614877M
Coronal loops, seen in solar coronal images, are believed to
represent emission from magnetic flux tubes with compact cross
sections. We examine the 3D structure of plasma above an active
region in a radiative magnetohydrodynamic simulation to locate volume
counterparts for coronal loops. In many cases, a loop cannot be linked
to an individual thin strand in the volume. While many thin loops are
present in the synthetic images, the bright structures in the volume
are fewer and of complex shape. We demonstrate that this complexity
can form impressions of thin bright loops, even in the absence of thin
bright plasma strands. We demonstrate the difficulty of discerning
from observations whether a particular loop corresponds to a strand in
the volume, or a projection artifact. We demonstrate how apparently
isolated loops could deceive observers, even when observations from
multiple viewing angles are available. While we base our analysis
on a simulation, the main findings are independent from a particular
simulation setup and illustrate the intrinsic complexity involved in
interpreting observations resulting from line-of-sight integration
in an optically thin plasma. We propose alternative interpretation
for strands seen in Extreme Ultraviolet images of the corona. The
"coronal veil" hypothesis is mathematically more generic, and
naturally explains properties of loops that are difficult to address
otherwise-such as their constant cross section and anomalously high
density scale height. We challenge the paradigm of coronal loops as
thin magnetic flux tubes, offering new understanding of solar corona,
and by extension, of other magnetically confined bright hot plasmas.

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Title: Three-polarizer Treatment of Linear Polarization in
Coronagraphs and Heliospheric Imagers
Authors: DeForest, Craig E.; Seaton, Daniel B.; West, Matthew J.
2022ApJ...927...98D Altcode: 2021arXiv211211504D
Linearly polarized light has been used to view the solar corona
for over 150 years. While the familiar Stokes representation for
polarimetry is complete, it is best matched to a laboratory setting
and therefore is not the most convenient representation either for
coronal instrument design or for coronal data analysis. Over the last
100 years of development of coronagraphs and heliospheric imagers,
various representations have been used for both direct measurement
and analysis. These systems include famous representations such as
the (B, pB) system, which is analogous to the Stokes system in solar
observing coordinates, and also internal representations such as
in-instrument Stokes parameters with fixed or variable "vertical"
direction, and brightness values through a particular polarizing
optic or set thereof. Many polarimetric instruments currently use
a symmetric three-polarizer measurement and representation system
(which we refer to as "(M, Z, P)") to derive the (B, pB) or Stokes
parameters. We present a symmetric derivation of (B, pB) and Stokes
parameters from (M, Z, P), analyze the noise properties of (M, Z, P)
in the context of instrument design, develop (M, Z, P) as a useful
intermediate system for data analysis including background subtraction,
and draw a helpful analogy between linear polarimetric systems and
the large existing body of work on photometric colorimetry.

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Title: A Strategy for a Coherent and Comprehensive Basis for
Understanding the Middle Corona
Authors: West, M. J.; Seaton, D. B.; Alzate, N.; Caspi, A.; DeForest,
C. E.; Gilly, C. R.; Golub, L.; Higginson, A. K.; Kooi, J. E.; Mason,
J. P.; Rachmeler, L. A.; Reeves, K. K.; Reardon, K.; Rivera, Y. J.;
Savage, S.; Viall, N. M.; Wexler, D. B.
2022heli.conf.4060W Altcode:
We describe a strategy for coherent and comprehensive observations
needed to achieve a fundamental understanding of the middle solar
corona.

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Title: Small Satellite Mission Concepts for Space Weather Research
and as Pathfinders for Operations
Authors: Caspi, Amir; Barthelemy, M.; Bussy-Virat, C. D.; Cohen, I. J.;
DeForest, C. E.; Jackson, D. R.; Vourlidas, A.; Nieves-Chinchilla, T.
2022SpWea..2002554C Altcode: 2022arXiv220107426C
Recent advances in miniaturization and commercial availability of
critical satellite subsystems and detector technology have made
small satellites (SmallSats, including CubeSats) an attractive,
low-cost potential solution for space weather research and operational
needs. Motivated by the first International Workshop on SmallSats
for Space Weather Research and Forecasting, held in Washington,
DC on 1-4 August 2017, we discuss the need for advanced space
weather measurement capabilities, driven by analyses from the World
Meteorological Organization (WMO), and how SmallSats can efficiently
fill these measurement gaps. We present some current, recent missions
and proposed/upcoming mission concepts using SmallSats that enhance
space weather research and provide prototyping pathways for future
operational applications; how they relate to the WMO requirements;
and what challenges remain to be overcome to meet the WMO goals
and operational needs in the future. With additional investment from
cognizant funding agencies worldwide, SmallSats—including standalone
missions and constellations—could significantly enhance space weather
research and, eventually, operations, by reducing costs and enabling new
measurements not feasible from traditional, large, monolithic missions.

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Title: Can solar coronal plumelets precondition switchback events
in the wind?
Authors: Uritsky, Vadim; DeForest, Craig; Karpen, Judith; DeVore,
C. Richard; Kumar, Pankaj; Raouafi, Nour; Wyper, Peter
2021AGUFMSH24C..05U Altcode:
Filamentary structures and motions in plume images have been known
for many years (e.g., Raouafi &amp; Stenborg (2014) and references
therein). Recently, we have presented the first in-depth quantitative
investigation of these structures, which we denoted plumelets (Uritsky
et al., 2021). Using an extended set of high-resolution, high-cadence
solar coronal images covering 40 hr of nearly continuous observations
of a typical solar coronal plume by SDO/AIA on 2016 July 23, we have
investigated the highly dynamic nature of the plumelets. The figure
below (courtesy NASA/SDO) provides an example of processing of a
high-resolution SDO/AIA image to reveal distinct plumelets within the
studied plume. Our analysis has demonstrated that the impulsive behavior
of the plumelets may dominate the large-scale behavior of the host
plume. The plumelets support persistent longitudinal fluctuations whose
typical period (35 minutes) is consistent with the peak-power period
of the solar p-modes, and the radial propagation speed (190240 km/s)
is in agreement with the characteristic speed of plasma outflows in a
typical coronal hole jet. Elsewhere (Kumar et al., 2021), we present
evidence for direct causal connection between the plumelets, jetlets,
and localized reconnection activity observed at the plume base. In this
talk, we focus on the stability and spatio-temporal correlation pattern
of the velocity field in a system of multiple coronal plumelets. Our
analysis reveals significant transient velocity shears at the interface
boundaries of adjacent plumelets. We argue that these shears could lead
to a localized onset of Kelvin Helmholtz instability in the downstream
plume plasma, which could introduce topological irregularities in the
frozen-in magnetic field and facilitate the formation of switchbacks and
other small-scale structures in the magnetically connected solar wind.

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Title: Establishing flux rope chirality using white light polarization
data from the PUNCH mission
Authors: Gibson, Sarah; Morgan, Huw; Provornikova, Elena; Malanushenko,
Anna; DeForest, Craig; de Koning, Curt; Fan, Yuhong; Merkin,
Viacheslav; Webb, David
2021AGUFMSH32A..03G Altcode:
Interplanetary Coronal Mass Ejections (ICMEs) are generally expected
to incorporate coherently-twisted magnetic fields, i.e., magnetic
flux ropes. We expect and have observed to some extent evolution
and interactions between flux ropes and the background corona and
solar wind, including rotation, deflection, and potentially continued
topological changes. The upcoming PUNCH mission will provide a full
field of view from pole to pole and fill existing gaps between
coronagraphs and heliospheric imagers, and will obtain polarized
brightness measurements which may be used along with brightness
measurements as a powerful tool for imaging and localizing CME
substructure evolution in transit. Further analysis of these
substructures may then lead to information about the chirality, or
handedness of magnetic twist of the flux rope. In order to demonstrate
these capabilities, we present synthetic polarization from forward
modeled simulations of flux rope CMEs. We compare the 3D position
of substructure that can be extracted from these data to the ground
truth simulation knowledge of the position of mass along the line
of sight. We further consider the implications for chirality and the
robustness of the method to topological variation of the flux rope at
the heart of the ICME.

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Title: Polarimeter to UNify the Corona and Heliosphere: Mission
status, activity, and science planning
Authors: DeForest, Craig; Gibson, Sarah; Killough, Ronnie; Case,
Traci; Beasley, Matthew; Laurent, Glenn; Colaninno, Robin
2021AGUFMSH35C2090D Altcode:
The Polarimeter to UNify the Corona and Heliosphere (PUNCH) is an
in-development mission, now in a combined Phase C/D in the NASA mission
lifecycle, to image the outer solar corona and inner heliosphere as
a unified system. The flight assets comprise four spacecraft to be
launched to 6am/6pm Sun-synchronous Low-Earth Orbit; one spacecraft
carries a Narrow Field Imager (NFI) coronagraph, and three carry
copies of a Wide Field Imager (WFI) heliospheric imager. These prime
instruments are specifically designed to work together as a seamless
"virtual instrument" with a 90° FOV, centered on the Sun. PUNCH
will produce polarized (pB) and unpolarized (B) images of the young
solar wind as it forms and departs the Sun, allowing 3D analysis of
solar wind and CME structure and trajectory. Aa student-contributed
instrument, STEAM, comprises two solid-state X-ray spectrometers
to study coronal heating and flare physics. PUNCH has an open data
policy and all data products will be made available to everyone at
the same time as the mission team. PUNCH is working to a launch
readiness date of 3-Oct-2023. The PUNCH science team comprises
PI Craig DeForest, PS Sarah Gibson, and project Co-Investigators
and Associate Investigators. Organized into six working groups,
we are actively preparing for the 2-year prime mission starting
90 days after launch. Science team meetings are open to all,
and are announced in the usual venues and the PUNCH web page
(https://punch.space.swri.edu). Current preparations include forward
modeling, derivation of predicted image characteristics from existing
data, and development of a suite of analysis tools in the vigorous
open-source Python/NumPy/SunPy millieu. The mission is complemented by
the groundbreaking PUNCH Outreach Program (POP) centered around a theme
of ancient and modern sunwatching, and concentrated in the American
Southwest. POP is specifically designed to support national, as well as
regional, educational and outreach efforts and to stimulate interest
in science by engaging under-represented populations in the focus
region and around the nation. We will present the current technical
status of PUNCH, the primary science objectives and observing plan,
current preparation activity and working group structure, and pathways
to coordinate and/or get involved with the mission.

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Title: Translational Tomography with WISPR: Basis of Method and
Current Progress
Authors: Kenny, Megan; DeForest, Craig; West, Matthew; Liewer, Paulett
2021AGUFMSH42A..07K Altcode:
We present first steps toward "translational tomography" of the solar
corona, using images that WISPR has captured in recent perihelia. Our
method relies on known perspective changes due to the rapid trajectory
of PSP through the solar corona near perihelion. The method allows
extraction of feature location and large-scale structure near the
track of the spacecraft itself. To produce the inversions, we neglect
local proper motions and model the apparent kinematics of a stationary
solar wind feature, from WISPR's point of view. This family of analytic
functions serves as a partial basis for the vector space of WISPR image
sequences; a change-of-basis operation yields the initial tomogram. For
initial analyses we confine ourselves to the ribbon of material whose
length runs along the track of the spacecraft and whose width runs
perpendicular to that track (locally horizontal). We present the basics
of the method and initial test results from a pre-flight model and from
three recent perihelion passes. Future work includes regularization
of the basis vectors and improvement of the basic proof-of-concept
inversions. The tool will grow in utility as the orbital distances
decrease in future encounters.

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Title: The Multiview Observatory for Solar Terrestrial Science (MOST)
Authors: Gopalswamy, Nat; Kucera, Therese; Leake, James; MacDowall,
Robert; Wilson, Lynn; Kanekal, Shrikanth; Shih, Albert; Christe,
Steven; Gong, Qian; Viall, Nicholeen; Tadikonda, Sivakumar; Fung,
Shing; Yashiro, Seiji; Makela, Pertti; Golub, Leon; DeLuca, Edward;
Reeves, Katharine; Seaton, Daniel; Savage, Sabrina; Winebarger, Amy;
DeForest, Craig; Desai, Mihir; Bastian, Tim; Lazio, Joseph; Jensen,
P. E., C. S. P., Elizabeth; Manchester, Ward; Wood, Brian; Kooi,
Jason; Wexler, David; Bale, Stuart; Krucker, Sam; Hurlburt, Neal;
DeRosa, Marc; Pevtsov, Alexei; Tripathy, Sushanta; Jain, Kiran;
Gosain, Sanjay; Petrie, Gordon; Kholikov, Shukirjon; Zhao, Junwei;
Scherrer, Philip; Woods, Thomas; Chamberlin, Philip; Kenny, Megan
2021AGUFMSH12A..07G Altcode:
The Multiview Observatory for Solar Terrestrial Science (MOST) is a
comprehensive mission concept targeting the magnetic coupling between
the solar interior and the heliosphere. The wide-ranging imagery and
time series data from MOST will help understand the solar drivers and
the heliospheric responses as a system, discerning and tracking 3D
magnetic field structures, both transient and quiescent in the inner
heliosphere. MOST will have seven remote-sensing and three in-situ
instruments: (1) Magnetic and Doppler Imager (MaDI) to investigate
surface and subsurface magnetism by exploiting the combination of
helioseismic and magnetic-field measurements in the photosphere; (2)
Inner Coronal Imager in EUV (ICIE) to study large-scale structures
such as active regions, coronal holes and eruptive structures by
capturing the magnetic connection between the photosphere and the
corona to about 3 solar radii; (3) Hard X-ray Imager (HXI) to image
the non-thermal flare structure; (4) White-light Coronagraph (WCOR) to
seamlessly study transient and quiescent large-scale coronal structures
extending from the ICIE field of view (FOV); (5) Faraday Effect
Tracker of Coronal and Heliospheric structures (FETCH), a novel radio
package to determine the magnetic field structure and plasma column
density, and their evolution within 0.5 au; (6) Heliospheric Imager
with Polarization (HIP) to track solar features beyond the WCOR FOV,
study their impact on Earth, and provide important context for FETCH;
(7) Radio and Plasma Wave instrument (M/WAVES) to study electron beams
and shocks propagating into the heliosphere via passive radio emission;
(8) Solar High-energy Ion Velocity Analyzer (SHIVA) to determine spectra
of electrons, and ions from H to Fe at multiple spatial locations
and use energetic particles as tracers of magnetic connectivity; (9)
Solar Wind Magnetometer (MAG) to characterize magnetic structures at
1 au; (10) Solar Wind Plasma Instrument (SWPI) to characterize plasma
structures at 1 au. MOST will have two large spacecraft with identical
payloads deployed at L4 and L5 and two smaller spacecraft ahead of L4
and behind L5 to carry additional FETCH elements. MOST will build upon
SOHO and STEREO achievements to expand the multiview observational
approach into the first half of the 21st Century.

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Title: Direct Evidence for the Dynamic Chromospheric Origin of Solar
Coronal Plumes
Authors: Kumar, Pankaj; Karpen, Judy; Uritsky, Vadim; DeForest, Craig;
Raouafi, Nour; DeVore, C. Richard
2021AGUFMSH25F2145K Altcode:
Coronal plumes are long ray-like open structures in coronal
holes, and have been considered as possible sources for the fast
solarwind. Their origin in the largely unipolar coronal holes has long
been a mystery. Earlier spectroscopic and imaging observationshave
revealed blue-shifted plasma and propagating disturbances (PDs)
in plumes that are widely interpreted in terms of flowsand/or
propagating slow-mode waves, but these interpretations (flows vs
waves) are under debate. Recently we discovered an important clue
about plume internal structure: dynamic filamentary features called
plumelets, which account formost of the plume emission. Here we present
high-resolution observations from SDO/AIA and IRIS that revealed
numerous quasiperiodic tiny jets (so-called jetlets") associated
with transient brightening and plasma heating at the chromospheric
footpoints of the plumelets. By analogy to larger coronal jets,
these jetlets are most likely produced within the plume base by
magnetic reconnection between closed and open flux at a stressed
3D null point. The jetlet-associated brightenings are in phase with
plumelet-associated PDs, and vary with a period of 3 to 5 minutes,
which is remarkably consistent with the photospheric/chromospheric
p-mode oscillation. This reconnection at the open-closed boundary in
the chromosphere/transition region is likely modulated or driven by
local manifestations of the global p-mode waves. We discuss how these
quasiperiodic jetlets extend upward to become plumelets, contribute
mass to the solar wind, and may be sources of switchbacks recently
detected by the Parker Solar Probe.

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Title: SynCOM: Synthetic Corona Outflow Model for the Heliophysics
community
Authors: Moraes Filho, Valmir; Uritsky, Vadim; Thompson, Barbara;
DeForest, Craig
2021AGUFMSH24C..06M Altcode:
Numerous methods for measuring coronal flow velocities have been
developed over the years. These measurements are central to our
understanding of the origin of the solar wind and serving to upcoming
missions that address this problem, such as the Polarimeter to Unify the
Corona and Heliosphere (PUNCH) mission. However, many of the existing
flow tracking methods provide qualitatively reasonable outcomes, their
quantitative validation across the wide range of coronal altitudes
remains a problem. The lack of precise knowledge about the targeted
velocity field is the primary obstacle, making it impossible to compare
algorithms attempting to estimate flow parameters for the same coronal
structure. To address this problem, we are designing the Synthetic
Corona Outflow Model (SynCOM) an empirical data-driven model of a
dynamic solar corona based on previous high-resolution observations. The
SynCOM model mimics the transient and quasi-periodical behavior present
in the actual solar corona, such as the one observed by STEREO-A/COR
2. The SynCOM outputs exhibit a true-to-life radial decay of the
polarized brightness and include stochastic components accounting for
physical fluctuations of plasma outflows and instrumental noise. Since
the model has a predefined distribution of flow velocity and an
adjustable signal-to-noise ratio, it can be used for testing a variety
of data analysis methods used to measure coronal flows. Adjusting SynCOM
settings for specific coronal conditions and instrumental parameters
enables a straightforward comparison of accuracy and performance of
different data analysis methods and measurement techniques designed
to quantify velocity and acceleration in the corona. In this work,
we will present examples of the application of SynCOM for verifying
observational requirements for detecting coronal flows beyond the
range of altitudes covered by previously operated coronagraphs; and
benchmarking popular flow tracking codes used by the coronal physics
community, and cross-validating their outputs.

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Title: Tracing the Drivers of Slow Solar Wind in the Middle Corona
Authors: Chitta, Lakshmi Pradeep; Seaton, Daniel; Downs, Cooper;
DeForest, Craig; Higginson, Aleida
2021AGUFMSH24C..01C Altcode:
Compared to the so-called fast solar wind that originates from polar
coronal holes during the solar minimum, low-latitude wind streams
generally have lower speeds ( 500 km/s). These slow solar wind streams
closer to the ecliptic plane are characterized by their high spatial
structuring, temporal variability, and coronal compositions. The
magnetic driver responsible for the origin of this slow solar wind and
its characteristics, however, is not well understood. Using coronal
observations from the 2018 off-pointing campaign of the GOES Solar
Ultraviolet Imager (SUVI) as well as images from SOHO/LASCO, we found
signatures of solar wind streams driven by magnetic reconnection
in the highly structured middle corona. In particular, elongated
coronal loops in the middle corona over a coronal-hole-active-region
complex are observed to reconnect and retract while in the process,
some plasma is propelled away from the Sun as streams or blobs. Using
STEREO observations we found that similar streams forming over the same
complex escape into the heliosphere. Our observations of reconnection
effects, however, are limited by the time resolution of the SUVI data
in that they clearly represent the tail of a distribution of event
durations, with a strong likelihood that many more events remain
unresolved in the current data. In this talk, we will present these
new results and discuss them in the context of models of slow solar
wind sources and drivers. our findings emphasize the key necessity of
having routine extreme ultraviolet observations of the middle coronal
processes from ecliptic and polar vantage points, along with extended
coronal diagnostics to develop better understanding of the heliospheric
impact of Sun's activity.

---------------------------------------------------------
Title: The PUNCH Outreach Program A New Pathway for NASA
Mission-Embedded Outreach
Authors: Morrow, Cherilynn; DeForest, Craig
2021AGUFMED14A..03M Altcode:
The NASA PUNCH mission will be uniquely capable of tracking space
weather features from the Suns outermost atmosphere all the way
to Earth orbit. The NASA Heliophysics Division approved the 5-year
PUNCH Outreach Program (POP) for funding in January 2021, referring
to it publicly as a new exemplar for mission-embedded outreach. The
POP engages PUNCH scientists in partnership with five planetariums
and science centers plus other multi-cultural partners to activate an
Ancient &amp; Modern Sun Watching theme designed to engage historically
marginalized populations. Shortly after NASA selected PUNCH to become a
NASA Small Explorer mission, PI Dr. Craig DeForest hired Dr. Cherilynn
Morrow as a consultant charged with building an outreach team and
developing a plan for an outreach program that would be considered
for funding via an augmentation to the mission budget. There were no
specific NASA guidelines. The PIs charge was two-fold: 1) to leverage
the mission to inspire diverse youth in the US Southwest, and 2) to
complement and extend whatever else NASA is doing in this domain. Former
NASA policy required Principal Investigators of NASA space science
missions to allocate 1-2% of mission costs for a program of education
and public outreach (EPO). This policy was supported by contemporary
Decadal Survey recommendations from the National Academy. However,
the mandate approach to EPO was not fully successful and was eventually
discontinued. Understandably, some considered the 1-2% policy a tax on
their time and funds in an unfamiliar domain that distracted them from
primary science objectives. The current approach by the Heliophysics
Division and by the PUNCH project deliberately assuage these concerns
to demonstrate effective embedding of an ambitious outreach program
within a NASA mission. This talk will share the 8 Guiding Principles
of the POP that are enabling PUNCH to realize the unique benefits
of an outreach program being closely associated with a NASA space
science mission while addressing lessons learned from past efforts and
seizing new opportunities afforded by the present landscape of NASA
public engagement. These Principles may be of broader value to other
scientific leaders and outreach professionals considering whether to
pursue support for mission-embedded outreach programs.

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Title: First observations from the SPICE EUV spectrometer on Solar
Orbiter
Authors: Fludra, A.; Caldwell, M.; Giunta, A.; Grundy, T.; Guest,
S.; Leeks, S.; Sidher, S.; Auchère, F.; Carlsson, M.; Hassler, D.;
Peter, H.; Aznar Cuadrado, R.; Buchlin, É.; Caminade, S.; DeForest,
C.; Fredvik, T.; Haberreiter, M.; Harra, L.; Janvier, M.; Kucera, T.;
Müller, D.; Parenti, S.; Schmutz, W.; Schühle, U.; Solanki, S. K.;
Teriaca, L.; Thompson, W. T.; Tustain, S.; Williams, D.; Young, P. R.;
Chitta, L. P.
2021A&A...656A..38F Altcode: 2021arXiv211011252F
 Aims: We present first science observations taken during the
commissioning activities of the Spectral Imaging of the Coronal
Environment (SPICE) instrument on the ESA/NASA Solar Orbiter
mission. SPICE is a high-resolution imaging spectrometer operating at
extreme ultraviolet (EUV) wavelengths. In this paper we illustrate
the possible types of observations to give prospective users a
better understanding of the science capabilities of SPICE. 
Methods: We have reviewed the data obtained by SPICE between April
and June 2020 and selected representative results obtained with
different slits and a range of exposure times between 5 s and 180
s. Standard instrumental corrections have been applied to the raw
data. Results: The paper discusses the first observations
of the Sun on different targets and presents an example of the full
spectra from the quiet Sun, identifying over 40 spectral lines from
neutral hydrogen and ions of carbon, oxygen, nitrogen, neon, sulphur,
magnesium, and iron. These lines cover the temperature range between
20 000 K and 1 million K (10 MK in flares), providing slices of the
Sun's atmosphere in narrow temperature intervals. We provide a list
of count rates for the 23 brightest spectral lines. We show examples
of raster images of the quiet Sun in several strong transition region
lines, where we have found unusually bright, compact structures in the
quiet Sun network, with extreme intensities up to 25 times greater
than the average intensity across the image. The lifetimes of these
structures can exceed 2.5 hours. We identify them as a transition
region signature of coronal bright points and compare their areas and
intensity enhancements. We also show the first above-limb measurements
with SPICE above the polar limb in C III, O VI, and Ne VIII lines, and
far off limb measurements in the equatorial plane in Mg IX, Ne VIII,
and O VI lines. We discuss the potential to use abundance diagnostics
methods to study the variability of the elemental composition that can
be compared with in situ measurements to help confirm the magnetic
connection between the spacecraft location and the Sun's surface,
and locate the sources of the solar wind. Conclusions: The
SPICE instrument successfully performs measurements of EUV spectra
and raster images that will make vital contributions to the scientific
success of the Solar Orbiter mission.

---------------------------------------------------------
Title: Small-Scale Solar Activity and its effect on the coronal
environment
Authors: Raouafi, Nour; Stenborg, Guillermo; Seaton, Daniel; DeForest,
Craig; Bale, Stuart; Horbury, Timothy; Kasper, Justin; Velli, Marco;
Karpen, Judith; Kumar, Pankaj; DeVore, C. Richard; Uritsky, Vadim
2021AGUFMSH25F2144R Altcode:
Careful analysis of solar observations reveals a myriad of small-scale
jetting activity (i.e., jetlets; Raouafi &amp; Stenborg 2014). Jetlets
are miniature manifestations of the typical coronal jets observed
in both X-rays and extreme-ultraviolet (EUV) solar images. They are
the product of near-ubiquitous magnetic reconnection. Their role in
energy and mass transport to the solar corona and wind has not been
yet well established. Here we provide an overview of this phenomenon
and explore its role at the base of the corona and the young solar
wind. We conjecture that these small dynamic features might be the
source or at least one of the sources of the magnetic switchbacks
observed by the Parker Solar Probe.

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Title: The Sun's dynamic extended corona observed in extreme
ultraviolet
Authors: Seaton, Daniel B.; Hughes, J. Marcus; Tadikonda, Sivakumara
K.; Caspi, Amir; DeForest, Craig E.; Krimchansky, Alexander; Hurlburt,
Neal E.; Seguin, Ralph; Slater, Gregory
2021NatAs...5.1029S Altcode: 2021arXiv210508028S; 2021NatAs.tmp..141S
The `middle corona' is a critical transition between the
highly disparate physical regimes of the lower and outer solar
coronae. Nonetheless, it remains poorly understood due to the
difficulty of observing this faint region (1.5-3 R⊙). New
observations from the Solar Ultraviolet Imager of a Geostationary
Operational Environmental Satellite in August and September 2018
provide the first comprehensive look at this region's characteristics
and long-term evolution in extreme ultraviolet. Our analysis shows
that the dominant emission mechanism here is resonant scattering
rather than collisional excitation, consistent with recent model
predictions. Our observations highlight that solar wind structures
in the heliosphere originate from complex dynamics manifesting in the
middle corona that do not occur at lower heights. These data emphasize
that low-coronal phenomena can be strongly influenced by inflows from
above, not only by photospheric motion, a factor largely overlooked
in current models of coronal evolution. This study reveals the full
kinematic profile of the initiation of several coronal mass ejections,
filling a crucial observational gap that has hindered understanding of
the origins of solar eruptions. These new data uniquely demonstrate how
extreme ultraviolet observations of the middle corona provide strong
new constraints on models seeking to unify the corona and heliosphere.

---------------------------------------------------------
Title: Mesoscale Structure in the Solar Wind
Authors: Viall, N. M.; DeForest, C. E.; Kepko, L.
2021FrASS...8..139V Altcode:
Structures in the solar wind result from two basic mechanisms:
structures injected or imposed directly by the Sun, and structures
formed through processing en route as the solar wind advects outward
and fills the heliosphere. On the largest scales, solar structures
directly impose heliospheric structures, such as coronal holes imposing
high speed streams of solar wind. Transient solar processes can inject
large-scale structure directly into the heliosphere as well, such as
coronal mass ejections. At the smallest, kinetic scales, the solar
wind plasma continually evolves, converting energy into heat, and all
structure at these scales is formed en route. `Mesoscale' structures,
with scales at 1 AU in the approximate spatial range of 5 Mm -10,000
Mm and temporal range of 10 s - 7 hrs, lie in the orders of magnitude
gap between the two size-scale extremes. Structures of this size regime
are created through both mechanisms. Competition between the imposed and
injected structures with turbulent and other evolution leads to complex
structuring and dynamics. The goal is to understand this interplay
and to determine which type of mesoscale structures dominate the solar
wind under which conditions. However, the mesoscale regime is also the
region of observation space that is grossly under-sampled. The sparse
in situ measurements that currently exist are only able to measure
individual instances of discrete structures, and are not capable of
following their evolution or spatial extent. Remote imaging has captured
global and large scale features and their evolution, but does not yet
have the sensitivity to measure most mesoscale structures and their
evolution. Similarly, simulations cannot model the global system while
simultaneously resolving kinetic effects. It is important to understand
the source and evolution of solar wind mesoscale structures because they
contain information on how the Sun forms the solar wind, and constrains
the physics of turbulent processes. Mesoscale structures also comprise
the ground state of space weather, continually buffeting planetary
magnetospheres. In this paper we describe the current understanding
of the formation and evolution mechanisms of mesoscale structures in
the solar wind, their characteristics, implications, and future steps
for research progress on this topic.

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Title: The CubeSat Imaging X-ray Solar Spectrometer (CubIXSS)
Authors: Caspi, A.; Shih, A. Y.; Panchapakesan, S.; Warren, H. P.;
Woods, T. N.; Cheung, M.; DeForest, C. E.; Klimchuk, J. A.; Laurent,
G. T.; Mason, J. P.; Palo, S. E.; Seaton, D. B.; Steslicki, M.;
Gburek, S.; Sylwester, J.; Mrozek, T.; Kowaliński, M.; Schattenburg,
M.; The CubIXSS Team
2021AAS...23821609C Altcode:
The CubeSat Imaging X-ray Solar Spectrometer (CubIXSS) is a 6U
CubeSat proposed to NASA H-FORT. CubIXSS is motivated by a compelling
overarching science question: what are the origins of hot plasma in
solar flares and active regions? Elemental abundances are a unique
diagnostic of how mass and energy flow into and within the corona,
and CubIXSS addresses its science question through sensitive, precise
measurements of abundances of key trace ion species, whose spectral
signatures reveal the chromospheric or coronal origins of heated plasma
across the entire temperature range from ~1 to &gt;30 MK. CubIXSS
measurements of the coronal temperature distribution and elemental
abundances directly address longstanding inconsistencies from prior
studies using instruments with limited, differing temperature and
composition sensitivities. CubIXSS comprises two co-optimized
and cross-calibrated instruments that fill a critical observational
gap: MOXSI, a novel diffractive spectral imager using a pinhole
camera and X-ray transmission diffraction grating for spectroscopy of
flares and active regions from 1 to 55 Å, with spectral and spatial
resolutions of 0.28-0.37 Å and 29-39 arcsec FWHM, respectively;
and SASS, a suite of four spatially-integrated off-the-shelf
spectrometers for high-cadence, high-sensitivity X-ray spectra from
0.5 to 50 keV, with spectral resolution of 0.06-0.5 keV FWHM across
that range. If selected for implementation, CubIXSS will launch
in late 2023 to mid-2024 to observe intense solar flares and active
regions during the rising phase and peak of the solar cycle. Its 1-year
prime mission is well timed with perihelia of Parker Solar Probe and
Solar Orbiter, and with the launches of complementary missions such
as the PUNCH Small Explorer. CubIXSS is a pathfinder for the next
generation of Explorer-class missions with improved capabilities for
SXR imaging spectroscopy. We present the CubIXSS motivating science
background, its suite of instruments and expected performances, and
other highlights from the completed Concept Study Report, including
novel analysis techniques to fully exploit the rich data set of CubIXSS
spectral observations.

---------------------------------------------------------
Title: Cross Sections of Coronal Loop Flux Tubes
Authors: Klimchuk, J. A.; DeForest, C.
2021AAS...23832808K Altcode:
Coronal loops reveal crucial information about the nature of
both coronal magnetic fields and coronal heating. The shape of the
corresponding flux tube cross section and how it varies with position
are especially important properties. They are a direct indication of
the expansion of the field and of the cross-field spatial distribution
of the heating. We have studied 20 loops using high spatial resolution
observations from the first flight of the Hi-C rocket experiment,
measuring the intensity and width as a function of position along
the loop axis. We find that intensity and width tend to either be
uncorrelated or to have a direct dependence, such that they increase
or decrease together. This implies that the flux tube cross sections
are approximately circular under the assumptions that the tubes have
non-negligible twist and that the plasma emissivity is approximately
uniform along the magnetic field. The shape need not be a perfect circle
and the emissivity need not be uniform within the cross section, but
sub-resolution patches of emission must be distributed quasi-uniformly
within an envelope that has an aspect ratio of order unity. This raises
questions about the suggestion that flux tubes expand with height,
but primarily in the line-of-sight direction so that the corresponding
(relatively noticeable) loops appear to have roughly uniform width,
a long-standing puzzle. It also casts doubt on the idea that most
loops correspond to simple warped sheets, although we leave open the
possibility of more complex manifold structures.

---------------------------------------------------------
Title: Fluxon Modeling of the Steady Solar Wind
Authors: Lowder, C.; Lamb, D.; DeForest, C.
2021AAS...23822904L Altcode:
We describe a novel method for modeling the global, steady solar
wind using observed photospheric magnetic fields as a driving boundary
condition. The Field Line Universal relaXer (FLUX) numerical code models
the solar corona as a collection of magnetic domains, represented by
a quasi-Lagrangian grid of discrete field lines (fluxons). Each fluxon
represents a quantized bundle of magnetic flux and responds to computed
magnetic tension and pressure forces from neighboring fluxons. The
model relaxes a collection of fluxons to solve the nonlinear force-free
field with a prescribed boundary and topology. Synoptic magnetogram data
are used to drive initial fluxon placement and topology, providing the
output of an observationally-driven relaxed coronal magnetic field. The
FLUX model provides an intermediate approach between rapid heuristic
methods and intensive 3D magnetohydrodynamic models, providing the best
of both worlds. The FLUX model has the distinct advantages of being
computationally efficient (scaling with the magnetic complexity of
the two-dimensional photospheric boundary) and preserving connectivity
to allow for tracking the history of a bundle of magnetic flux. Open
fluxons extending from the photospheric boundary are used to compute a
set of modified one-dimensional isothermal Parker solar wind solutions,
with transonic solutions interpolated to an outer spherical boundary
uniform grid at 21.5 solar radii for comparison with and distribution
to other heliospheric models. We describe the method, the simulation
code, and solar wind model results.

---------------------------------------------------------
Title: Polarimeter to UNify the Corona and Heliosphere: Science
Summary and Mission Status
Authors: Deforest, C.; Gibson, S.; Killough, R.; Beasley, M.; Laurent,
G.; Colaninno, R.; The Punch Team
2021AAS...23831304D Altcode:
The Polarimeter to UNify the Corona and Heliosphere (PUNCH) is a
constellation mission being built within NASA's Small Explorer
program. During its two year nominal mission, PUNCH will use a
constellation of four spacecraft as a single visible-light "virtual
coronagraph" with a 90° outer field of view and a 1.25° inner field
of view, to continuously produce global, photometric, 3D images of the
outer reaches of the solar corona and the solar wind itself. PUNCH uses
polarization properties of Thomson scattering to extract 3D information
along its single line of sight from near Earth. The PUNCH science
objectives are to understand both (1) how coronal structures become
the ambient solar wind, and (2) the dynamic evolution of transient
structures within the solar wind. Subtopics include mapping the
evolving flow of the solar wind, identifying microstructures and
turbulence in the young solar wind, locating the Alfvén surface
and other natural boundaries of the corona-heliosphere system,
tracking CMEs and their evolution in 3D, measuring the formation
of solar wind co-rotating interaction regions, and determining the
large-scale dynamics of interplanetary shocks. These are addressed
through deep-field 3D imaging, using the polarization properties
of Thomson-scattered light. PUNCH is finishing up its Phase B
(preliminary design), with KDP-C expected in 2021 July and a Launch
Readiness Date in late 2023. This poster summarizes the science
objectives, novel approach, and current status of the mission.

---------------------------------------------------------
Title: Inward-propagating Plasma Parcels in the Solar Corona: Models
with Aerodynamic Drag, Ablation, and Snowplow Accretion
Authors: Cranmer, Steven R.; DeForest, Craig E.; Gibson, Sarah E.
2021ApJ...913....4C Altcode: 2021arXiv210312039C
Although the solar wind flows primarily outward from the Sun to
interplanetary space, there are times when small-scale plasma inflows
are observed. Inward-propagating density fluctuations in polar coronal
holes were detected by the COR2 coronagraph on board the STEREO-A
spacecraft at heliocentric distances of 7-12 solar radii, and these
fluctuations appear to undergo substantial deceleration as they move
closer to the Sun. Models of linear magnetohydrodynamic waves have
not been able to explain these deceleration patterns, so they have
been interpreted more recently as jets from coronal sites of magnetic
reconnection. In this paper, we develop a range of dynamical models
of discrete plasma parcels with the goal of better understanding the
observed deceleration trend. We found that parcels with a constant
mass do not behave like the observed flows, and neither do parcels
undergoing ablative mass loss. However, parcels that accrete mass in
a snowplow-like fashion can become decelerated as observed. We also
extrapolated OMNI in situ data down to the so-called Alfvén surface
and found that the initial launch point for the observed parcels may
often be above this critical radius. In other words, in order for the
parcels to flow back down to the Sun, their initial speeds are probably
somewhat nonlinear (i.e., supra-Alfvénic), and thus the parcels may be
associated with structures such as shocks, jets, or shear instabilities.

---------------------------------------------------------
Title: Critical Science Plan for the Daniel K. Inouye Solar Telescope
(DKIST)
Authors: Rast, Mark P.; Bello González, Nazaret; Bellot Rubio,
Luis; Cao, Wenda; Cauzzi, Gianna; Deluca, Edward; de Pontieu, Bart;
Fletcher, Lyndsay; Gibson, Sarah E.; Judge, Philip G.; Katsukawa,
Yukio; Kazachenko, Maria D.; Khomenko, Elena; Landi, Enrico; Martínez
Pillet, Valentín; Petrie, Gordon J. D.; Qiu, Jiong; Rachmeler,
Laurel A.; Rempel, Matthias; Schmidt, Wolfgang; Scullion, Eamon; Sun,
Xudong; Welsch, Brian T.; Andretta, Vincenzo; Antolin, Patrick; Ayres,
Thomas R.; Balasubramaniam, K. S.; Ballai, Istvan; Berger, Thomas E.;
Bradshaw, Stephen J.; Campbell, Ryan J.; Carlsson, Mats; Casini,
Roberto; Centeno, Rebecca; Cranmer, Steven R.; Criscuoli, Serena;
Deforest, Craig; Deng, Yuanyong; Erdélyi, Robertus; Fedun, Viktor;
Fischer, Catherine E.; González Manrique, Sergio J.; Hahn, Michael;
Harra, Louise; Henriques, Vasco M. J.; Hurlburt, Neal E.; Jaeggli,
Sarah; Jafarzadeh, Shahin; Jain, Rekha; Jefferies, Stuart M.; Keys,
Peter H.; Kowalski, Adam F.; Kuckein, Christoph; Kuhn, Jeffrey R.;
Kuridze, David; Liu, Jiajia; Liu, Wei; Longcope, Dana; Mathioudakis,
Mihalis; McAteer, R. T. James; McIntosh, Scott W.; McKenzie, David
E.; Miralles, Mari Paz; Morton, Richard J.; Muglach, Karin; Nelson,
Chris J.; Panesar, Navdeep K.; Parenti, Susanna; Parnell, Clare E.;
Poduval, Bala; Reardon, Kevin P.; Reep, Jeffrey W.; Schad, Thomas A.;
Schmit, Donald; Sharma, Rahul; Socas-Navarro, Hector; Srivastava,
Abhishek K.; Sterling, Alphonse C.; Suematsu, Yoshinori; Tarr, Lucas
A.; Tiwari, Sanjiv; Tritschler, Alexandra; Verth, Gary; Vourlidas,
Angelos; Wang, Haimin; Wang, Yi-Ming; NSO and DKIST Project; DKIST
Instrument Scientists; DKIST Science Working Group; DKIST Critical
Science Plan Community
2021SoPh..296...70R Altcode: 2020arXiv200808203R
The National Science Foundation's Daniel K. Inouye Solar Telescope
(DKIST) will revolutionize our ability to measure, understand,
and model the basic physical processes that control the structure
and dynamics of the Sun and its atmosphere. The first-light DKIST
images, released publicly on 29 January 2020, only hint at the
extraordinary capabilities that will accompany full commissioning of
the five facility instruments. With this Critical Science Plan (CSP)
we attempt to anticipate some of what those capabilities will enable,
providing a snapshot of some of the scientific pursuits that the DKIST
hopes to engage as start-of-operations nears. The work builds on the
combined contributions of the DKIST Science Working Group (SWG) and
CSP Community members, who generously shared their experiences, plans,
knowledge, and dreams. Discussion is primarily focused on those issues
to which DKIST will uniquely contribute.

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Title: Plumelets: Dynamic Filamentary Structures in Solar Coronal
Plumes
Authors: Uritsky, V. M.; DeForest, C. E.; Karpen, J. T.; DeVore,
C. R.; Kumar, P.; Raouafi, N. E.; Wyper, P. F.
2021ApJ...907....1U Altcode: 2020arXiv201205728U
Solar coronal plumes long seemed to possess a simple geometry
supporting spatially coherent, stable outflow without significant
fine structure. Recent high-resolution observations have challenged
this picture by revealing numerous transient, small-scale, collimated
outflows ("jetlets") at the base of plumes. The dynamic filamentary
structure of solar plumes above these outflows, and its relationship
with the overall plume structure, have remained largely unexplored. We
analyzed the statistics of continuously observed fine structure inside
a single representative bright plume within a mid-latitude coronal
hole during 2016 July 2-3. By applying advanced edge-enhancement and
spatiotemporal analysis techniques to extended series of high-resolution
images from the Solar Dynamics Observatory's Atmospheric Imaging
Assembly, we determined that the plume was composed of numerous
time-evolving filamentary substructures, referred to as "plumelets" in
this paper, that accounted for most of the plume emission. The number
of simultaneously identifiable plumelets was positively correlated
with plume brightness, peaked in the fully formed plume, and remained
saturated thereafter. The plumelets had transverse widths of 10 Mm and
intermittently supported upwardly propagating periodic disturbances with
phase speeds of 190-260 km s-1 and longitudinal wavelengths
of 55-65 Mm. The characteristic frequency (≍ 3.3 mHz) is commensurate
with that of solar p-modes. Oscillations in neighboring plumelets
are uncorrelated, indicating that the waves could be driven by p-mode
flows at spatial scales smaller than the plumelet separation. Multiple
independent sources of outflow within a single coronal plume should
impart significant fine structure to the solar wind that may be
detectable by Parker Solar Probe and Solar Orbiter.

---------------------------------------------------------
Title: Tracking CME substructure evolution through the solar wind
Authors: Gibson, S. E.; DeForest, C.; de Koning, C. A.; Fan, Y.;
Malanushenko, A. V.; Merkin, V. G.; Provornikova, E.; Thompson, B. J.;
Webb, D. F.
2020AGUFMSH0280005G Altcode:
Future coronagraphs and heliospheric imagers, in particular those
to be launched on the PUNCH mission, will have the capability to
track the evolution of CME substructures as the CME moves through and
interacts with the solar wind. We present analysis using polarization
data obtained from forward modeling simulations of CMEs in the corona
and inner heliosphere. We use these data to track the evolution
of substructures in three dimensions, and consider the diagnostic
potential of internal substructure vs structure at the front of the
CME. In particular, we develop methods for extracting information
about chirality of CME magnetic flux ropes from polarization data.

---------------------------------------------------------
Title: Relative coronal abundance diagnostics with Solar Orbiter/SPICE
Authors: Zambrana Prado, N.; Buchlin, E.; Peter, H.; Young, P. R.;
Auchere, F.; Carlsson, M.; Fludra, A.; Hassler, D.; Aznar Cuadrado,
R.; Caminade, S.; Caldwell, M.; DeForest, C.; Fredvik, T.; Harra,
L.; Janvier, M.; Kucera, T. A.; Giunta, A. S.; Grundy, T.; Müller,
D.; Parenti, S.; Schmutz, W. K.; Schühle, U.; Sidher, S.; Teriaca,
L.; Thompson, W. T.; Williams, D.
2020AGUFMSH038..09Z Altcode:
Linking solar activity on the surface and in the corona to the inner
heliosphere is one of Solar Orbiter's main goals. Its UV spectrometer
SPICE (SPectral Imaging of the Coronal Environment) will provide
relative abundance measurements which will be key in this quest
as different structures on the Sun have different abundances as a
consequence of the FIP (First Ionization Potential) effect. Solar
Orbiter's unique combination of remote sensing and in-situ instruments
coupled with observation from other missions such as Parker Solar
Probe will allow us to compare in-situ and remote sensing composition
data. With the addition of modeling, these new results will allow us
to trace back the source of heliospheric plasma. As high telemetry
will not always be available with SPICE, we have developed a method
for measuring relative abundances that is both telemetry efficient
and reliable. Unlike methods based on Differential Emission Measure
(DEM) inversion, the Linear Combination Ratio (LCR) method does not
require a large number of spectral lines. This new method is based
on linear combinations of UV spectral lines. The coefficients of
the combinations are optimized such that the ratio of two linear
combinations of radiances would yield the relative abundance of two
elements. We present some abundance diagnostics tested on different
combinations of spectral lines observable by SPICE.

---------------------------------------------------------
Title: Contemporary Analysis Methods for Coronagraph and Heliospheric
Imager Data
Authors: Thompson, B. J.; Attie, R.; Chhiber, R.; Cranmer, S. R.;
DeForest, C.; Gallardo-Lacourt, B.; Gibson, S. E.; Jones, S. I.;
Moraes Filho, V.; Reginald, N. L.; Uritsky, V. M.; Viall, N. M.
2020AGUFMSH031..05T Altcode:
Coronagraphs, polarimeters, and heliospheric imagers are providing
new insight into how structures in the solar wind form and develop as
they flow from the inner corona into the heliosphere. With this comes
a whole new frontier of physical observables in 3D, including kinetic
(velocity and acceleration), thermodynamic (density, temperature, and
shock boundary), and magnetic field properties. These measurements
inform and challenge models of global solar wind flow, turbulence,
and CME propagation. We will discuss recent advances in quantifying
physical properties of the corona and solar wind using coronagraph
and heliospheric imager data, and make predictions of what new models
and instrumentation (including the in-development PUNCH mission)
will bring us in the future.

---------------------------------------------------------
Title: Dynamics and thermal structure in the quiet Sun seen by SPICE
Authors: Peter, H.; Aznar Cuadrado, R.; Schühle, U.; Teriaca, L.;
Auchere, F.; Carlsson, M.; Fludra, A.; Hassler, D.; Buchlin, E.;
Caminade, S.; Caldwell, M.; DeForest, C.; Fredvik, T.; Harra, L. K.;
Janvier, M.; Kucera, T. A.; Giunta, A. S.; Grundy, T.; Müller, D.;
Parenti, S.; Schmutz, W. K.; Sidher, S.; Thompson, W. T.; Williams,
D.; Young, P. R.
2020AGUFMSH038..03P Altcode:
We will present some of the early data of the Spectral Imaging of the
Coronal Environment (SPICE) instrument on Solar Orbiter. One of the
unique features of SPICE is its capability to record a wide range of
wavelengths in the extreme UV with the possibility to record spectral
lines giving access to a continuous plasma temperature range from 10.000
K to well above 1 MK. The data taken so far were for commissioning
purposes and they can be used for a preliminary evaluation of the
science performance of the instrument. Here we will concentrate on
sample spectra covering the whole wavelength region and on the early
raster maps acquired in bright lines in the quiet Sun close to disk
center. Looking at different quiet Sun features we investigate the
thermal structure of the atmosphere and flow structures. For this
we apply fits to the spectral profiles and check the performance in
terms of Doppler shifts and line widths to retrieve the structure of
the network in terms of dynamics. While the amount of data available
so far is limited, we will have a first look on how quiet Sun plasma
responds to heating events. For this, we will compare spectral lines
forming at different temperatures recorded at strictly the same time.

---------------------------------------------------------
Title: The CubeSat Imaging X-ray Solar Spectrometer (CubIXSS)
Authors: Caspi, A.; Shih, A. Y.; Warren, H.; Winebarger, A. R.; Woods,
T. N.; Cheung, C. M. M.; DeForest, C.; Klimchuk, J. A.; Laurent,
G. T.; Mason, J. P.; Palo, S. E.; Schwartz, R.; Seaton, D. B.;
Steslicki, M.; Gburek, S.; Sylwester, J.; Mrozek, T.; Kowaliński,
M.; Schattenburg, M.
2020AGUFMSH0480007C Altcode:
The CubeSat Imaging X-ray Solar Spectrometer (CubIXSS) is a 6U
CubeSat currently in a formulation phase under the 2019 NASA H-FORT
program. CubIXSS is motivated by a compelling overarching science
question: what are the origins of hot plasma in solar flares and active
regions? Elemental abundances are a unique diagnostic of how mass
and energy flow into and within the corona, and CubIXSS addresses
its science question through sensitive, precise measurements of
abundances of key trace ion species, whose spectral signatures reveal
the chromospheric or coronal origins of heated plasma across the
entire range of coronal temperatures, from ~1 to &gt;30 MK. CubIXSS
measurements of the coronal temperature distribution and elemental
abundances directly address longstanding inconsistencies from prior
studies using instruments with limited, differing temperature and
composition sensitivities. CubIXSS comprises two co-optimized and
cross-calibrated instruments that fill a critical observational gap:
MOXSI, a novel diffractive spectral imager using a pinhole camera
and X-ray transmission diffraction grating to achieve spectroscopy of
flares and active regions from 1 to 55 Å, with spectral resolution of
0.24 Å FWHM and a spatial resolution of 25 arcsec FWHM; and SASS,
a suite of four spatially-integrated off-the-shelf spectrometers for
high-cadence, high-sensitivity measurements of soft and hard X-rays,
from 0.5 to 50 keV, with spectral resolution from 0.06 to 0.5 keV
FWHM. If selected for implementation, CubIXSS will launch in
mid-2023 to observe intense solar flares and active regions during
the rising phase of the solar cycle. Its nominal 1-year mission is
well timed with perihelia of Parker Solar Probe and Solar Orbiter,
and with the launches of complementary missions such as the PUNCH
Small Explorer. CubIXSS is also a pathfinder for the next generation
of Explorer-class missions with improved capabilities for SXR imaging
spectroscopy. We present the CubIXSS motivating science background, its
suite of instruments and expected performances, and other highlights
from the completed Concept Study Report, including novel analysis
techniques to fully exploit the rich data set of CubIXSS spectral
observations.

---------------------------------------------------------
Title: Why (And How) We Should Observe The Dynamic Middle Corona
Authors: Seaton, D. B.; Caspi, A.; DeForest, C.; Hughes, M.
2020AGUFMSH0300001S Altcode:
Although the solar corona is the primary driver of almost all
plasma dynamics throughout the solar system, the precise nature of
the connection between the corona and heliosphere remains poorly
understood. Parker Solar Probe observations from 0.3 AU have revealed
a highly structured environment shaped by flows and ejecta interacting
with the corona's complex magnetic field. Critically, significant
physical transitions in the middle corona — i.e. from closed to
open magnetic field and, in some locations, low to high plasma beta
— govern the overall connectivity between the inner corona and
heliosphere. However, observations of this region remain scarce, and
completely connecting PSP observations to the low corona remains a
challenge. New approaches to observations, particularly in the EUV,
can fully reveal this region, its dynamics, and connectivity to the
outer corona, opening the door to resolving a decades-old mystery about
the relationship between the solar wind, solar eruptions, and the low
corona. In this talk we demonstrate how new observations will lead to
the development of coherent understanding of the corona and heliosphere
as a single system in a region where deep connections have previously
only been inferred. We discuss the variability of the middle corona
we see in these observations, and what this variability reveals about
the importance of the evolving Sun's influence on the heliosphere as
a whole.

---------------------------------------------------------
Title: First Results From SPICE EUV Spectrometer on Solar Orbiter
Authors: Fludra, A.; Caldwell, M.; Giunta, A. S.; Grundy, T.; Guest,
S.; Sidher, S.; Auchere, F.; Carlsson, M.; Hassler, D.; Peter, H.;
Aznar Cuadrado, R.; Buchlin, E.; Caminade, S.; DeForest, C.; Fredvik,
T.; Harra, L. K.; Janvier, M.; Kucera, T. A.; Leeks, S.; Mueller,
D.; Parenti, S.; Schmutz, W. K.; Schühle, U.; Teriaca, L.; Thompson,
W. T.; Tustain, S.; Williams, D.; Young, P. R.
2020AGUFMSH038..02F Altcode:
SPICE (Spectral Imaging of Coronal Environment) is one of the remote
sensing instruments onboard Solar Orbiter. It is an EUV imaging
spectrometer observing the Sun in two wavelength bands: 69.6-79.4 nm
and 96.6-105.1 nm. SPICE is capable of recording full spectra in these
bands with exposures as short as 1s. SPICE is the only Solar Orbiter
instrument that can measure EUV spectra from the disk and low corona
of the Sun and record all spectral lines simultaneously. SPICE uses
one of three narrow slits, 2"x11', 4”x11', 6”x11', or a wide slit
30”x14'. The primary mirror can be scanned in a direction perpendicular
to the slit, allowing raster images of up to 16' in size. We
present an overview of the first SPICE data taken on several days
during the instrument commissioning carried out by the RAL Space team
between 2020 April 21 and 2020 June 14. We also include results from
SPICE observations at the first Solar Orbiter perihelion at 0.52AU,
taken between June 16-21st. We give examples of full spectra
from the quiet Sun near disk centre and provide a list of key spectral
lines emitted in a range of temperatures between 10,000 K and over 1
million K, from neutral hydrogen and ions of carbon, oxygen, nitrogen,
neon, sulphur and magnesium. We show examples of first raster images
in several strong lines, obtained with different slits and a range
of exposure times between 5s and 180s. We describe the temperature
coverage and density diagnostics, determination of plasma flows, and
discuss possible applications to studies of the elemental abundances
in the corona. We also show the first off-limb measurements with SPICE,
as obtained when the spacecraft pointed at the limb.

---------------------------------------------------------
Title: New Insights into the Dynamic Relationship between Jetlets
and Plumes
Authors: Kumar, P.; Karpen, J. T.; Uritsky, V. M.; DeForest, C.;
Raouafi, N. E.; DeVore, C. R.
2020AGUFMSH0240002K Altcode:
Plumes are among the most fascinating large-scale coronal structures,
but also are among the most puzzling and controversial features. They
are significantly denser and have lower flow speeds than the inter-plume
regions, and are rooted in regions of fine-scale, highly mixed magnetic
polarity within predominantly unipolar coronal holes. The advent of
high-resolution, high-cadence coronal observations from the Solar
Dynamics Observatory's Atmospheric Imaging Assembly (SDO/AIA), coupled
with photospheric magnetograms from SDO's Helioseismic and Magnetic
Imager (SDO/HMI), has enabled detailed studies of plumes from their
footprints outward. In particular, the detection of small transient
outflows at the base of a few plumes led to the hypothesis that these
"jetlets" are the long-sought source of plume mass and energy that
sustain them for hours to weeks (Raouafi &amp; Stenborg 2014). We
have analyzed high-cadence multiwavelength SDO/AIA data and SDO/HMI
magnetograms for a well-observed plume on 2016 July 3, focusing on
the activity at the base and the fine structure within the overlying
plume. In contrast to earlier studies, we used a noise-gating method
(DeForest 2017) to clean the AIA and HMI data that revealed in greater
detail the jetlets and other small-scale structures throughout the
plume. Our investigation revealed multiple quasi-periodic jetlets within
the multipolar footpoint region, throughout the period of observation,
as well as evolving filamentary structures above the jetlets. This
presentation will discuss the measured and derived jetlet properties,
the structural and dynamic connections between the jetlets and the
plume, and implications for the underlying physical processes. DeForest C. E., Noise-gating to Clean Astrophysical Image Data,
ApJ, 838, 155 (2017) Raouafi, N. E. &amp; G. Stenborg, Role of
Transients in the Sustainability of Solar Coronal Plumes, ApJ, 787,
118 (2014)

---------------------------------------------------------
Title: Velocity Flow Fields Derived from Coronagraph Data
Authors: Moraes Filho, V.; DeForest, C.; Thompson, B. J.; Uritsky,
V. M.
2020AGUFMSH0280004M Altcode:
In anticipation of the PUNCH mission, we examine deep exposure data
from the special campaign of the STEREO SECCHI COR2 instrument. Data
collected over April 14-16, 2014, representing altitudes of 4-15 solar
radii, show clear flow structures throughout the field of view. We
examine the variations in the derived flow as a function of altitude
and polar angle, to present a picture of the solar wind velocities
and acceleration through the corona and inner heliosphere.

---------------------------------------------------------
Title: Plumelets: Dynamic Filamentary Structures in Solar Plumes
Authors: Karpen, J. T.; Uritsky, V. M.; DeForest, C.; DeVore, C. R.;
Kumar, P.; Raouafi, N. E.; Wyper, P. F.
2020AGUFMSH0240003K Altcode:
Solar plumes long seemed to possess a simple geometry supporting
spatially coherent, stable outflow without significant fine
structure. Recent high-resolution observations have challenged
this picture by revealing numerous transient, small-scale,
collimated outflows ("jetlets") at the base of plumes (see Kumar et
al. presentation in this session). The dynamic filamentary structure
of solar plumes above these outflows, and its relationship with
the overall plume structure, have remained largely unexplored. We
report a statistical analysis of continuously observed fine structure
inside a bright plume within a mid-latitude coronal hole during 2016
July 2-3. By applying advanced edge-enhancement and spatiotemporal
analysis techniques to extended series of highresolution images
from the Solar Dynamics Observatory's Atmospheric Imaging Assembly,
we determined that the plume was composed of numerous time-evolving
bright filamentary substructures, referred to as "plumelets" in this
paper, that accounted for most of the plume emission. The number of
simultaneously identifiable plumelets varied over the observation
period, was positively correlated with plume brightness, and peaked
in the fully formed plume. The plumelets had transverse widths of
10 Mm and intermittently supported upwardly propagating periodic
disturbances with phase speeds of 190-260 km s-1 and
longitudinal wavelengths of 55-65 Mm. The characteristic frequency
(3.5 mHz) is commensurate with that of solar p-modes. Oscillations
in neighboring plumelets are uncorrelated, indicating that the waves
could be driven by p-mode flows at spatial scales smaller than the
plumelet separation. Multiple independent sources of outflow within a
single coronal plume should impart significant fine structure to the
fast solar wind and be detectable by Parker Solar Probe at perihelion.

---------------------------------------------------------
Title: Shear-Driven Transition to Isotropically Turbulent Solar Wind
Outside the Alfvén Critical Zone
Authors: Ruffolo, D. J.; Matthaeus, W. H.; Chhiber, R.; Usmanov, A. V.;
Yang, Y.; Bandyopadhyay, R.; Parashar, T.; Goldstein, M. L.; DeForest,
C.; Wan, M.; Chasapis, A.; Maruca, B.; Velli, M. C. M.; Kasper, J. C.
2020AGUFMSH0290010R Altcode:
Motivated by prior remote observations of a transition from striated
solar coronal structures to more isotropic "flocculated" fluctuations,
we propose that the dynamics of the inner solar wind just outside the
Alfvén critical zone, and in the vicinity of the first β=1 surface,
is powered by the relative velocities of adjacent coronal magnetic flux
tubes. We suggest that large amplitude flow contrasts are magnetically
constrained at lower altitude but shear-driven dynamics are triggered
as such constraints are released above the Alfvén critical zone, as
suggested by global magnetohydrodynamic (MHD) simulations that include
self-consistent turbulence transport. We argue that this dynamical
evolution accounts for features observed by Parker Solar Probe ( PSP)
near initial perihelia, including magnetic "switchbacks", and large
transverse velocities that are partially corotational and saturate
near the local Alfvén speed. Large-scale magnetic increments are more
longitudinal than latitudinal, a state unlikely to originate in or
below the lower corona. We attribute this to preferentially longitudinal
velocity shear from varying degrees of corotation. Supporting evidence
includes comparison with a high Mach number three-dimensional
compressible MHD simulation of nonlinear shear-driven turbulence,
reproducing several observed diagnostics, including characteristic
distributions of fluctuations that are qualitatively similar to PSP
observations near the first perihelion. The concurrence of evidence from
remote sensing observations, in situ measurements, and both global and
local simulations supports the idea that the dynamics just above the
Alfvén critical zone boost low-frequency plasma turbulence to the level
routinely observed throughout the explored solar system. This research
has been supported in part by grant RTA6280002 from Thailand Science
Research and Innovation and the Parker Solar Probe mission under the
ISOIS project (contract NNN06AA01C) and a subcontract to University of
Delaware from Princeton University (SUB0000165). M.L.G. acknowledges
support from the Parker Solar Probe FIELDS MAG team. Y.Y. is supported
in part by NSFC grant 11902138. Additional support is acknowledged from
the NASA LWS program (NNX17AB79G) and the HSR program (80NSSC18K1210
&amp; 80NSSC18K1648).

---------------------------------------------------------
Title: Cross Sections of Coronal Loop Flux Tubes
Authors: Klimchuk, J. A.; DeForest, C.
2020AGUFMSH0370001K Altcode:
Coronal loops reveal crucial information about the nature of
both coronal magnetic fields and coronal heating. The shape of the
corresponding flux tube cross section and how it varies with position
are especially important properties. They are a direct indication of
the expansion of the field and of the cross-field spatial distribution
of the heating. We have studied 20 loops using high spatial resolution
observations from the first flight of the Hi-C rocket experiment,
measuring the intensity and width as a function of position along
the loop axis. We find that intensity and width tend to either be
uncorrelated or to have a direct dependence, such that they increase
or decrease together. This implies that the flux tube cross sections
are approximately circular under the assumptions that the tubes have
non-negligible twist and that the plasma emissivity is approximately
uniform along the magnetic field. The shape need not be a perfect circle
and the emissivity need not be uniform within the cross section, but
sub-resolution patches of emission must be distributed quasi-uniformly
within an envelope that has an aspect ratio of order unity. This raises
questions about the suggestion that flux tubes expand with height,
but primarily in the line-of-sight direction so that the corresponding
(relatively noticeable) loops appear to have roughly uniform width,
a long-standing puzzle. It also casts doubt on the idea that most
loops correspond to simple warped sheets, although we leave open the
possibility of more complex manifold structures.

---------------------------------------------------------
Title: Improving Multiday Solar Wind Forecasts
Authors: Elliott, H. A.; Arge, C. N.; Henney, C. J.; Dayeh, M. A.;
Livadiotis, G.; Jahn, J. M.; DeForest, C.
2020AGUFMSM030..01E Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The Polarimeter to UNify the Corona and Heliosphere (PUNCH)
Small Explorer Mission: Status and Next Steps
Authors: DeForest, C. E.; Killough, R.; Gibson, S. E.; Beasley, M.;
Henry, A.; Laurent, G. T.; Colaninno, R. C.
2020AGUFMSH0280002D Altcode:
The Polarimeter to UNify the Corona and Heliosphere (PUNCH) is a NASA
Small Explorer mission, to understand the solar corona and young
solar wind as a complete system. Science objectives are to measure
and understand how the ambient solar wind arises from the corona,
and to understand how transient events (such as CMEs) propagate and
evolve in the inner heliosphere. PUNCH uses direct, global, spatially
continuous, three dimensional imaging in polarized visible light,
to observe the outer corona and inner heliosphere as elements of a
single, connected system. PUNCH comprises four matched and synchronized
small-satellite observatories, operating as a "virtual instrument"
to image Thomson-scattered light from low-Earth orbit. PUNCH is the
first coronal and solar wind imaging mission designed specifically to
produce 3D images from a single vantage point using the polarization
properties of Thomson scattering. In addition, it will produce routine,
several-times-per-day maps of solar wind flow throughout the top of the
corona and bottom of the inner heliosphere, based on motion analysis
of the image stream. PUNCH has an open data policy and is seeking
scientific engagement throughout the heliophysics community. PUNCH
is wrapping up its Phase B (preliminary design), and is working toward
a 2023 launch for a two-year nominal mission. We present a very brief
overview of the mission, describe current status and next steps, and
indicate how to engage with the PUNCH science team and upcoming mission.

---------------------------------------------------------
Title: Calibrating optical distortions in the Solar Orbiter SPICE
spectrograph
Authors: Thompson, W. T.; Schühle, U.; Young, P. R.; Auchere, F.;
Carlsson, M.; Fludra, A.; Hassler, D.; Peter, H.; Aznar Cuadrado, R.;
Buchlin, E.; Caldwell, M.; DeForest, C.; Fredvik, T.; Harra, L. K.;
Janvier, M.; Kucera, T. A.; Giunta, A. S.; Grundy, T.; Müller, D.;
Parenti, S.; Caminade, S.; Schmutz, W. K.; Teriaca, L.; Williams,
D.; Sidher, S.
2020AGUFMSH0360029T Altcode:
The Spectral Imaging of the Coronal Environment (SPICE) instrument on
Solar Orbiter is a high-resolution imaging spectrometer operating
at extreme ultraviolet (EUV) wavelengths from 70.4-79.0 nm and
97.3-104.9 nm. A single-mirror off-axis paraboloid focuses the solar
image onto the entrance slit of the spectrometer section. A Toroidal
Variable Line Space (TVLS) grating images the entrance slit onto a
pair of MCP-intensified APS detectors. Ray-tracing analysis prior
to launch showed that the instrument was subject to a number of
small image distortions which need to be corrected in the final data
product. We compare the ray tracing results with measurements made in
flight. Co-alignment with other telescopes on Solar Orbiter will also
be examined.

---------------------------------------------------------
Title: First results from the EUI and SPICE observations of Alpha
Leo near Solar Orbiter first perihelion
Authors: Buchlin, E.; Teriaca, L.; Giunta, A. S.; Grundy, T.; Andretta,
V.; Auchere, F.; Peter, H.; Berghmans, D.; Carlsson, M.; Fludra, A.;
Harra, L.; Hassler, D.; Long, D.; Rochus, P. L.; Schühle, U.; Aznar
Cuadrado, R.; Caldwell, M.; Caminade, S.; DeForest, C.; Fredvik, T.;
Gissot, S.; Heerlein, K.; Janvier, M.; Kraaikamp, E.; Kucera, T. A.;
Müller, D.; Parenti, S.; Schmutz, W. K.; Sidher, S.; Smith, P.;
Stegen, K.; Thompson, W. T.; Verbeeck, C.; Williams, D.; Young, P. R.
2020AGUFMSH0360024B Altcode:
On June 16th 2020 Solar Orbiter made a dedicated observing campaign
where the spacecraft pointed to the solar limb to allow some of the
high resolution instruments to observe the ingress (at the east limb)
and later the egress (west limb) of the occultation of the star Alpha
Leonis by the solar disk. The star was chosen because its luminosity and
early spectral type ensure high and stable flux at wavelengths between
100 and 122 nanometers, a range observed by the High Resolution EUI
Lyman alpha telescope (HRI-LYA) and by the long wavelength channel
of the SPICE spectrograph. Star observations, when feasible, allow
to gather a great deal of information on the instrument performances,
such as the radiometric performance and the instrument optical point
spread function (PSF). We report here the first results from the
above campaign for the two instruments.

---------------------------------------------------------
Title: Spectroscopic Constraints on the Dimension of Active Region
Loops Along the Line of Sight
Authors: Kucera, T. A.; Young, P. R.; Klimchuk, J. A.; DeForest, C.
2020AGUFMSH041..05K Altcode:
Understanding the cross sections of coronal loops and how they vary
along the loop is important both for understanding coronal heating
and how the loops are shaped by the coronal magnetic field. To better
address this question we have developed a new method to constrain the
dimension of loops along the line of sight by utilizing spectroscopic
observations. We apply this method to a cool (5.5&lt;logT&lt;6.2)
loop using data from the Hinode/EUV Imaging Spectrometer (EIS) with
supporting data from Solar Dynamic Observatory (SDO) and the Solar
TErrestrial RElations Observatory (STEREO), and discuss the results and
their limitations. Our results are consistent with circular loop cross
sections, but could also be consistent with aspect ratios of 2 or 3.

---------------------------------------------------------
Title: First results from combined EUI and SPICE observations of
Lyman lines of Hydrogen and He II
Authors: Teriaca, L.; Aznar Cuadrado, R.; Giunta, A. S.; Grundy, T.;
Parenti, S.; Auchere, F.; Vial, J. C.; Fludra, A.; Berghmans, D.;
Carlsson, M.; Harra, L.; Hassler, D.; Long, D.; Peter, H.; Rochus,
P. L.; Schühle, U.; Buchlin, E.; Caldwell, M.; Caminade, S.; DeForest,
C.; Fredvik, T.; Gissot, S.; Heerlein, K.; Janvier, M.; Kraaikamp,
E.; Kucera, T. A.; Mueller, D.; Schmutz, W. K.; Sidher, S.; Smith, P.;
Stegen, K.; Thompson, W. T.; Verbeeck, C.; Williams, D.; Young, P. R.
2020AGUFMSH0360003T Altcode:
The Solar Orbiter spacecraft carries a powerful set of remote
sensing instruments that allow studying the solar atmosphere with
unprecedented diagnostic capabilities. Many such diagnostics require
the simultaneous usage of more than one instrument. One example of that
is the capability, for the first time, to obtain (near) simultaneous
spatially resolved observations of the emission from the first three
lines of the Lyman series of hydrogen and of He II Lyman alpha. In fact,
the SPectral Imaging of the Coronal Environment (SPICE) spectrometer
can observe the Lyman beta and gamma lines in its long wavelength
(SPICE-LW) channel, the High Resolution Lyman Alpha (HRI-LYA) telescope
of the Extreme Ultraviolet Imager (EUI) acquires narrow band images in
the Lyman alpha line while the Full Disk Imager (FSI) of EUI can take
images dominated by the Lyman alpha line of ionized Helium at 30.4 nm
(FSI-304). Being hydrogen and helium the main components of our star,
these very bright transitions play an important role in the energy
budget of the outer atmosphere via radiative losses and the measurement
of their profiles and radiance ratios is a fundamental constraint to
any comprehensive modelization effort of the upper solar chromosphere
and transition region. Additionally, monitoring their average ratios
can serve as a check out for the relative radiometric performance of
the two instruments throughout the mission. Although the engineering
data acquired so far are far from ideal in terms of time simultaneity
(often only within about 1 h) and line coverage (often only Lyman beta
was acquired by SPICE and not always near simultaneous images from all
three telescopes are available) the analysis we present here still
offers a great opportunity to have a first look at the potential of
this diagnostic from the two instruments. In fact, we have identified
a series of datasets obtained at disk center and at various positions
at the solar limb that allow studying the Lyman alpha to beta radiance
ratio and their relation to He II 30.4 as a function of the position
on the Sun (disk center versus limb and quiet Sun versus coronal holes).

---------------------------------------------------------
Title: Shear-driven Transition to Isotropically Turbulent Solar Wind
Outside the Alfvén Critical Zone
Authors: Ruffolo, D.; Matthaeus, W. H.; Chhiber, R.; Usmanov, A. V.;
Yang, Y.; Bandyopadhyay, R.; Parashar, T. N.; Goldstein, M. L.;
DeForest, C. E.; Wan, M.; Chasapis, A.; Maruca, B. A.; Velli, M.;
Kasper, J. C.
2020ApJ...902...94R Altcode: 2020arXiv200906537R
Motivated by prior remote observations of a transition from striated
solar coronal structures to more isotropic "flocculated" fluctuations,
we propose that the dynamics of the inner solar wind just outside the
Alfvén critical zone, and in the vicinity of the first $\beta =1$
surface, is powered by the relative velocities of adjacent coronal
magnetic flux tubes. We suggest that large-amplitude flow contrasts are
magnetically constrained at lower altitude but shear-driven dynamics are
triggered as such constraints are released above the Alfvén critical
zone, as suggested by global magnetohydrodynamic (MHD) simulations
that include self-consistent turbulence transport. We argue that this
dynamical evolution accounts for features observed by Parker Solar Probe
(PSP) near initial perihelia, including magnetic "switchbacks," and
large transverse velocities that are partially corotational and saturate
near the local Alfvén speed. Large-scale magnetic increments are more
longitudinal than latitudinal, a state unlikely to originate in or
below the lower corona. We attribute this to preferentially longitudinal
velocity shear from varying degrees of corotation. Supporting evidence
includes comparison with a high Mach number three-dimensional
compressible MHD simulation of nonlinear shear-driven turbulence,
reproducing several observed diagnostics, including characteristic
distributions of fluctuations that are qualitatively similar to PSP
observations near the first perihelion. The concurrence of evidence
from remote sensing observations, in situ measurements, and both global
and local simulations supports the idea that the dynamics just above
the Alfvén critical zone boost low-frequency plasma turbulence to
the level routinely observed throughout the explored solar system.

---------------------------------------------------------
Title: The Solar Orbiter SPICE instrument. An extreme UV imaging
spectrometer
Authors: SPICE Consortium; Anderson, M.; Appourchaux, T.; Auchère, F.;
Aznar Cuadrado, R.; Barbay, J.; Baudin, F.; Beardsley, S.; Bocchialini,
K.; Borgo, B.; Bruzzi, D.; Buchlin, E.; Burton, G.; Büchel, V.;
Caldwell, M.; Caminade, S.; Carlsson, M.; Curdt, W.; Davenne, J.;
Davila, J.; Deforest, C. E.; Del Zanna, G.; Drummond, D.; Dubau,
J.; Dumesnil, C.; Dunn, G.; Eccleston, P.; Fludra, A.; Fredvik, T.;
Gabriel, A.; Giunta, A.; Gottwald, A.; Griffin, D.; Grundy, T.; Guest,
S.; Gyo, M.; Haberreiter, M.; Hansteen, V.; Harrison, R.; Hassler,
D. M.; Haugan, S. V. H.; Howe, C.; Janvier, M.; Klein, R.; Koller,
S.; Kucera, T. A.; Kouliche, D.; Marsch, E.; Marshall, A.; Marshall,
G.; Matthews, S. A.; McQuirk, C.; Meining, S.; Mercier, C.; Morris,
N.; Morse, T.; Munro, G.; Parenti, S.; Pastor-Santos, C.; Peter, H.;
Pfiffner, D.; Phelan, P.; Philippon, A.; Richards, A.; Rogers, K.;
Sawyer, C.; Schlatter, P.; Schmutz, W.; Schühle, U.; Shaughnessy,
B.; Sidher, S.; Solanki, S. K.; Speight, R.; Spescha, M.; Szwec, N.;
Tamiatto, C.; Teriaca, L.; Thompson, W.; Tosh, I.; Tustain, S.; Vial,
J. -C.; Walls, B.; Waltham, N.; Wimmer-Schweingruber, R.; Woodward,
S.; Young, P.; de Groof, A.; Pacros, A.; Williams, D.; Müller, D.
2020A&A...642A..14S Altcode: 2019arXiv190901183A; 2019arXiv190901183S
 Aims: The Spectral Imaging of the Coronal Environment (SPICE)
instrument is a high-resolution imaging spectrometer operating at
extreme ultraviolet wavelengths. In this paper, we present the concept,
design, and pre-launch performance of this facility instrument on the
ESA/NASA Solar Orbiter mission. Methods: The goal of this paper
is to give prospective users a better understanding of the possible
types of observations, the data acquisition, and the sources that
contribute to the instrument's signal. Results: The paper
discusses the science objectives, with a focus on the SPICE-specific
aspects, before presenting the instrument's design, including optical,
mechanical, thermal, and electronics aspects. This is followed by a
characterisation and calibration of the instrument's performance. The
paper concludes with descriptions of the operations concept and data
processing. Conclusions: The performance measurements of the
various instrument parameters meet the requirements derived from the
mission's science objectives. The SPICE instrument is ready to perform
measurements that will provide vital contributions to the scientific
success of the Solar Orbiter mission.

---------------------------------------------------------
Title: Cross Sections of Coronal Loop Flux Tubes
Authors: Klimchuk, James A.; DeForest, Craig E.
2020ApJ...900..167K Altcode: 2020arXiv200715085K
Coronal loops reveal crucial information about the nature of
both coronal magnetic fields and coronal heating. The shape of the
corresponding flux tube cross section and how it varies with position
are especially important properties. They are a direct indication of
the expansion of the field and of the cross-field spatial distribution
of the heating. We have studied 20 loops using high spatial resolution
observations from the first flight of the Hi-C rocket experiment,
measuring the intensity and width as a function of position along
the loop axis. We find that intensity and width tend to either be
uncorrelated or to have a direct dependence, such that they increase
or decrease together. This implies that the flux tube cross sections
are approximately circular under the assumptions that the tubes have
nonnegligible twist and that the plasma emissivity is approximately
uniform along the magnetic field. The shape need not be a perfect circle
and the emissivity need not be uniform within the cross section, but
subresolution patches of emission must be distributed quasi-uniformly
within an envelope that has an aspect ratio of order unity. This raises
questions about the suggestion that flux tubes expand with height,
but primarily in the line-of-sight direction so that the corresponding
(relatively noticeable) loops appear to have roughly uniform width,
a long-standing puzzle. It also casts doubt on the idea that most
loops correspond to simple warped sheets, although we leave open the
possibility of more complex manifold structures.

---------------------------------------------------------
Title: A New Facility for Airborne Solar Astronomy: NASA's WB-57 at
the 2017 Total Solar Eclipse
Authors: Caspi, Amir; Seaton, Daniel B.; Tsang, Constantine C. C.;
DeForest, Craig E.; Bryans, Paul; DeLuca, Edward E.; Tomczyk,
Steven; Burkepile, Joan T.; Casey, Thomas "Tony"; Collier, John;
Darrow, Donald "DD"; Del Rosso, Dominic; Durda, Daniel D.; Gallagher,
Peter T.; Golub, Leon; Jacyna, Matthew; Johnson, David "DJ"; Judge,
Philip G.; Klemm, Cary "Diddle"; Laurent, Glenn T.; Lewis, Johanna;
Mallini, Charles J.; Parent, Thomas "Duster"; Propp, Timothy; Steffl,
Andrew J.; Warner, Jeff; West, Matthew J.; Wiseman, John; Yates,
Mallory; Zhukov, Andrei N.; NASA WB-57 2017 Eclipse Observing Team
2020ApJ...895..131C Altcode: 2020arXiv200409658C
NASA's WB-57 High Altitude Research Program provides a deployable,
mobile, and stratospheric platform for scientific research. Airborne
platforms are of particular value for making coronal observations
during total solar eclipses because of their ability both to follow the
Moon's shadow and to get above most of the atmospheric air mass that
can interfere with astronomical observations. We used the 2017 August
21 eclipse as a pathfinding mission for high-altitude airborne solar
astronomy, using the existing high-speed visible-light and near/midwave
infrared imaging suite mounted in the WB-57 nose cone. In this paper,
we describe the aircraft, the instrument, and the 2017 mission;
operations and data acquisition; and preliminary analysis of data
quality from the existing instrument suite. We describe benefits and
technical limitations of this platform for solar and other astronomical
observations. We present a preliminary analysis of the visible-light
data quality and discuss the limiting factors that must be overcome
with future instrumentation. We conclude with a discussion of lessons
learned from this pathfinding mission and prospects for future research
at upcoming eclipses, as well as an evaluation of the capabilities of
the WB-57 platform for future solar astronomy and general astronomical
observation.

---------------------------------------------------------
Title: Imaging the Solar Corona From Within
Authors: Hess, P.; Howard, R.; Vourlidas, A.; Bothmer, V.; Colaninno,
R.; DeForest, C.; Gallagher, B.; Hall, J. R.; Higginson, A.; Korendyke,
C.; Kouloumvakos, A.; Lamy, P.; Liewer, P.; Linker, J.; Linton, M.;
Penteado, P.; Plunkett, S.; Poirer, N.; Raouafi, N.; Rich, N.; Rochus,
P.; Rouillard, A.; Socker, D.; Stenborg, G.; Thernisien, A.; Viall, N.
2020AAS...23514907H Altcode:
Parker Solar Probe (PSP), launched, in August 2018 is humanity's
first probe of a stellar atmosphere. It will make measurements of
the near-Sun plasma from 'within' the outer corona with gradually
reduced perihelia from its first perihelia of 35 Rs in 2018-19 to 9.8
Rs in 2025. Here we report the results from the imaging observations
of the electron and dust corona, whe PSP was 35-54 Rs from the solar
surface, taken by the Wide-field Imager for Solar Probe (WISPR). The
spacecraft was near-corotating with the solar corona throughout the
observing window, which is an unprecedented situation for any type of
coronal imaging. Our initial analysis uncovers a long-hypothesized
depletion of the primordial dust orbiting near the Sun, reveals the
plasma structure of small-scale ejections, and provides a strict test
for validating model predictions of the large-scale configuration of
the coronal plasma. Thus, WISPR imaging allows the study of near-Sun
dust dynamics as the mission progresses. The high-resolution images
of small transients, largely unresolved from 1 AU orbits, unravel
the sub-structures of small magnetic flux ropes and show that the
Sun continually releases helical magnetic fields in the background
wind. Finally, WISPR's observations of the coronal streamer evolution
confirm the large-scale topology of the solar corona but they also
reveal that, as recently predicted, streamers are composed of yet
smaller sub-streamers channeling continual density fluctuations at
all visible scales.

---------------------------------------------------------
Title: Narrow Field Imager (NFI) for the Polarimeter to Unify the
Corona and Heliosphere (PUNCH)
Authors: Colaninno, R. C.; Howard, R. A.; McMullin, D. R.; Carter,
M. T.; Thernisien, A.; DeForest, C.; Laurent, G. T.; Beasley, M.;
Dancheck, J.; Hagood, R.; Eisenhower, K.; Hunt, T.; Chua, D. H.;
Brechbiel, D.; Noya, M.
2019AGUFMSH41E3300C Altcode:
The Narrow Field Imager (NFI) is a coronagraph designed as part of
Polarimeter to Unify the Corona and Heliosphere (PUNCH) to providing the
first complete, photometric, high-resolution views of the corona/solar
wind transition. The PUNCH payload also includes three Wide Field
Imagers (WFIs) heliospheric images provided by the Southwest Research
Institute (SwRI). Together, these instruments form a single "virtual
instrument" covering the entire inner solar system continuously from 6
to 180 R⊙ (1.5°-45° solar elongation). Each instrument
will be hosted on a 1+3 microsatellite constellation deployed into
sun-synchronous LEO. NFI implements a high heritage coronagraph design
to observe the inner heliosphere from 5.4 - 32 Rʘ with an
annular, sun-centered FOV. NFI achieves the PUNCH required performance
within the microsatellite mission concept with a simplified design that
exploits heritage from previous space-borne coronagraphs, including
SOHO/LASCO C3 and STEREO/SECCHI, and extensive design effort for the
similar NOAA Compact Coronagraph (CCOR). We prototyped and tested
the NFI stray-light suppression assembly (SSA) at NRL which confirms
the expected performance of the SSA and demonstrates the simplified
NFI design for the specific application to PUNCH. This work was
sponsored by NASA and the Chief of Naval Research.

---------------------------------------------------------
Title: Imaging the Solar Corona from Within: First Results from the
Parker Solar Probe Telescope
Authors: Howard, R. A.; Vourlidas, A.; Bothmer, V.; Colaninno, R. C.;
DeForest, C.; Gallagher, B.; Hall, J. R.; Hess, P.; Higginson, A. K.;
Korendyke, C.; Kouloumvakos, A.; Lamy, P.; Liewer, P. C.; Linker, J.;
Linton, M.; Penteado, P. F.; Plunkett, S. P.; Poirier, N.; Raouafi,
N.; Rich, N.; Rochus, P. L.; Rouillard, A. P.; Socker, D. G.; Stenborg,
G.; Thernisien, A.; Viall, N. M.
2019AGUFMSH11A..04H Altcode:
Parker Solar Probe (PSP) launched in August 2018 is humanity's
first probe of a stellar atmosphere. It will make measurements of
the near-Sun plasma from 'within' the outer corona with gradually
reduced perihelia from its first perihelia of 35 Rs in 2018-19 to 9.8
Rs in 2025. Here we report the results from the imaging observations
of the electron and dust corona, whe PSP was 35-54 Rs from the solar
surface, taken by the Wide-field Imager for Solar Probe (WISPR). The
spacecraft was near-corotating with the solar corona throughout the
observing window, which is an unprecedented situation for any type of
coronal imaging. Our initial analysis uncovers a long-hypothesized
depletion of the primordial dust orbiting near the Sun, reveals the
plasma structure of small-scale ejections, and provides a strict test
for validating model predictions of the large-scale configuration of
the coronal plasma. Thus, WISPR imaging allows the study of near-Sun
dust dynamics as the mission progresses. The high-resolution images
of small transients, largely unresolved from 1 AU orbits, unravel
the sub-structures of small magnetic flux ropes and show that the
Sun continually releases helical magnetic fields in the background
wind. Finally, WISPR's observations of the coronal streamer evolution
confirm the large-scale topology of the solar corona but they also
reveal that, as recently predicted, streamers are composed of yet
smaller sub-streamers channeling continual density fluctuations at
all visible scales.

---------------------------------------------------------
Title: Volume-filling Simulations of Coronal Loops Heated by
Nanoflares
Authors: Plowman, J.; Barnes, W.; Bradshaw, S. J.; Caspi, A.; DeForest,
C.; Klimchuk, J. A.
2019AGUFMSH53B3380P Altcode:
We present results of a coronal simulation consisting of loop strands
that fill the coronal volume in a self-consistent fashion. The
simulation is heated by a fully controllable 3D distribution, which
can be specified independent of the loop geometry and can include
nanoflares and continuous heating. The heating is then mapped to the
loop strands, and the physics of each strand are simulated using the
HYDRAD field-aligned hydrodynamics code. The simulation is applied
to a small example active region and used to produce synthetic AIA
data, which are then processed to produce a distribution of coronal
EUV brightening events. This distribution is then compared with that
found in the real AIA data for the same region, and we use the results
to determine if the observations are consistent with our prescribed
heating distribution.

---------------------------------------------------------
Title: Wide-Field Imager (WFI) for the Polarimeter to Unify the
Corona and Heliosphere (PUNCH)
Authors: Laurent, G. T.; DeForest, C.; Beasley, M.; Brownsberger, J.;
Clapp, M.; Colaninno, R. C.; Howard, R. A.; McMullin, D. R.; Nagler,
A.; Shoffner, M.; Smith, K. D.; Thernisien, A.; Waltham, N.
2019AGUFMSH41E3299L Altcode:
The Wide-Field Imager (WFI) is one of three polarizing heliospheric
imagers designed as part of Polarimeter to Unify the Corona and
Heliosphere (PUNCH) to providing the first complete, photometric,
high-resolution views of the corona/solar wind transition. The
PUNCH payload also includes a Narrow-Field Imager (NFI) provided
by The U.S. Naval Research Laboratory. Together, these instruments
form a single "virtual instrument" covering the entire inner solar
system continuously from 6 to 180 R⊙(1.5°-45° solar
elongation, ɛ). Each instrument will be hosted on a 1+3 microsatellite
constellation deployed into Sun-synchronous LEO. WFI implements a
high heritage planar/corral hybrid baffle design to observe the inner
heliosphere from 5°-45° in ɛ. As each WFI orbits Earth, it scans
the entire range of solar azimuths once per orbit. WFI achieves the
PUNCH required performance within the microsatellite mission concept
with a high sunlight attenuation factor of 10-16 based on
heritage designs of the STEREO/HI and SoloHI heliospheric imagers. SwRI
has developed, tested, and environmentally qualified a WFI prototype
instrument, confirming the expected performance of the baffle and
optics as designed for PUNCH.

---------------------------------------------------------
Title: Combining Remote and in situ Parker Solar Probe and STEREO
Data to Understand Solar Wind Density Structures
Authors: Viall, N. M.; Howard, R. A.; Vourlidas, A.; DeForest, C.;
Kasper, J. C.; Korreck, K. E.; Case, A. W.; Stevens, M. L.; Whittlesey,
P. L.; Larson, D. E.; Livi, R.; Szabo, A.; Kepko, L.; Lavraud, B.;
Rouillard, A. P.; Velli, M.
2019AGUFMSH13C3432V Altcode:
The instrument suite on Parker Solar Probe offers an unprecedented
viewpoint of the ambient solar wind and structure therein, shortly after
its formation and release from the solar corona. We take advantage of
the synergistic observations of the first Parker Solar Probe encounters
and the STEREO COR2 deep field campaigns covering the same time periods
to study mesoscale solar wind density structures. They often occur
in a quasi-periodic train, especially near the heliospheric current
sheet. Some may be a consequence of the development of dynamics en
route; many are remnants of the formation and release of the solar
wind, and provide important constraints on solar wind models. The
opportunity to combine the different observing angles and fields of
view of the white light WISPR observations and white light STEREO COR2
observations with in situ density and plasma measurements from SWEAP
allows better understanding of the characteristics and properties of
mesoscale density structures. The in situ data measure precise size
scales, plasma boundaries, and relationships between density and
other parameters. They help in the interpretation of the structures
seen in white light images and in unraveling projection effects. The
white light images enhance the in situ data by providing global
heliospheric context, as well as the occurrence rate and 2-D size
scales of structures as a function of latitude and distance from the
Sun. Together, these observations provide crucial constraints on the
formation of structures in the solar wind.

---------------------------------------------------------
Title: Flocculation, switchbacks, and loss of Alfvenicity: Indicators
of shear-driven turbulence in the young solar wind?
Authors: Matthaeus, W. H.; Ruffolo, D. J.; DeForest, C.; Parashar,
T.; Goldstein, M. L.; Roberts, D. A.; Chhiber, R.; Usmanov, A. V.;
Dudok de Wit, T.; Bandyopadhyay, R.; Chasapis, A.; Maruca, B.; Velli,
M. C. M.; Kasper, J. C.
2019AGUFMSH53B3374M Altcode:
Since the first preliminary announcements of Parker Solar Probe
results [1], there has been increased discussion of "switchbacks"
and speed enhancements such as those observed in Helios data [2]. A
familiar explanation relies on outward propagation of large amplitude
remnants of magnetic reconnection at lower altitudes. Such a mechanism
is plausible and difficult to rule out. However, another possibility
exists, namely that the onset of strong shear-driven turbulence,
beginning just outside the Alfvén critical region, may induce the
switchbacks through large-scale perturbation of the flow. This scenario
is consistent with a suite of observable effects already apparent in
imaging [3] and in situ datasets [2]. DeForest et al. interpreted the
transition from elongated striae to relatively isotropic flocculae
as a signature of the onset of shear-driven turbulent activity some
20-80 Rs from the photosphere, where the magnetic field ceases to be
a dominant constraint on transverse motions; this interpretation has
received support from turbulence-driven global simulations of the solar
wind [4]. The presence of velocity shears is also strongly suggested by
coronal imaging at lower altitudes [5]. Somewhere above the conventional
Alfvén point such shears can begin supplying turbulence energy [6]
while also destroying Alfvénicity by injection of kinetic energy but
not cross helicity [7]. If indeed the flocculation signifies large
fluctuations or even turnover associated with vortices, then specific
features of shear driven turbulence may be anticipated in imaging data
from the upcoming PUNCH mission and in ongoing analysis of in situ
Parker Solar Probe observations. Details of these signatures will be
given here. Research supported in part by grant RTA5980003 from the
Thailand Research Fund, by NASA under NNX17AB79G, 80NSSC18K1210,
80NSSC18K1648, and by the PSP ISOIS project as subcontract under
NNN06AA01C. [1] S. Bale, invited talk, 2018 Fall AGU Meeting
[2] T. Horbury, L. Matteini &amp; D. Stansby, MNRAS 478, 1980
(2018) [3] C. DeForest et al., Astrophys. J. 828, 66 (2016) [4] R. Chhiber et al., Astophys. J. Lett. 856, L39 (2018) [5]
C. DeForest et al., Astrophys. J. 862, 18 (2018) [6] G. Zank et
al., JGR 101, 17093 (1996); B. Breech et al., JGR 113, A08105 (2008)
[7] D. A. Roberts et al., JGR 97, 17115 (1992); see also Fig. 3
of D. A. Roberts, Astrophys. J. 711, 1044 (2010)

---------------------------------------------------------
Title: Near-Sun observations of an F-corona decrease and K-corona
fine structure
Authors: Howard, R. A.; Vourlidas, A.; Bothmer, V.; Colaninno, R. C.;
DeForest, C. E.; Gallagher, B.; Hall, J. R.; Hess, P.; Higginson,
A. K.; Korendyke, C. M.; Kouloumvakos, A.; Lamy, P. L.; Liewer, P. C.;
Linker, J.; Linton, M.; Penteado, P.; Plunkett, S. P.; Poirier, N.;
Raouafi, N. E.; Rich, N.; Rochus, P.; Rouillard, A. P.; Socker, D. G.;
Stenborg, G.; Thernisien, A. F.; Viall, N. M.
2019Natur.576..232H Altcode:
Remote observations of the solar photospheric light scattered by
electrons (the K-corona) and dust (the F-corona or zodiacal light)
have been made from the ground during eclipses1 and from
space at distances as small as 0.3 astronomical units2-5 to
the Sun. Previous observations6-8 of dust scattering have
not confirmed the existence of the theoretically predicted dust-free
zone near the Sun9-11. The transient nature of the corona
has been well characterized for large events, but questions still
remain (for example, about the initiation of the corona12
and the production of solar energetic particles13) and
for small events even its structure is uncertain14. Here
we report imaging of the solar corona15 during the first
two perihelion passes (0.16-0.25 astronomical units) of the Parker
Solar Probe spacecraft13, each lasting ten days. The view
from these distances is qualitatively similar to the historical views
from ground and space, but there are some notable differences. At
short elongations, we observe a decrease in the intensity of the
F-coronal intensity, which is suggestive of the long-sought dust
free zone9-11. We also resolve the fine-scale plasma
structure of very small eruptions, which are frequently ejected from
the Sun. These take two forms: the frequently observed magnetic flux
ropes12,16 and the predicted, but not yet observed, magnetic
islands17,18 arising from the tearing-mode instability in
the current sheet. Our observations of the coronal streamer evolution
confirm the large-scale topology of the solar corona, but also reveal
that, as recently predicted19, streamers are composed of
yet smaller substreamers channelling continual density fluctuations
at all visible scales.

---------------------------------------------------------
Title: PUNCH: a new view on the middle corona
Authors: Gibson, S. E.; DeForest, C.
2019AGUFMSH13A..06G Altcode:
The Polarimeter to UNify the Corona and Heliosphere (PUNCH)
has recently been selected by NASA as a Small Explorer mission,
to be launched as early as 2022. PUNCH uses a constellation of
three wide-field heliospheric imagers and a central near-field
coronagraphic imager to span the interface between the corona and the
inner heliosphere. Polarized and unpolarized images will be obtained
with greater than ten times the sensitivity of current instruments in
the region covering 6-15 solar radii, i.e., the upper portion of the
"middle corona". This will provide unprecedented views of the global
structure of fast/slow wind flow boundaries, CME substructure and
chirality, and the Alfven zone. This last is of particular interest to
this session, because the riotous torrent that is the young solar wind
implies the boundary between magnetically-dominated and wind-dominated
plasma is likely to be fractal and space-filling. Thus, it is a zone
that likely riddles the middle corona.

---------------------------------------------------------
Title: Modeling the Steady Solar Wind with an Observationally Driven
Fluxon Coronal Magnetic Field
Authors: Lowder, C.; Lamb, D. A.; DeForest, C.
2019AGUFMSH53B3398L Altcode:
Here we describe the development of a flexible and efficient framework
for a real-time capable solar wind predictive model. Our model allows
for the isolation of geometric expansion in open magnetic fieldlines to
explore the role of geometry in setting solar wind speed and density,
distinct from other effects such as intermittent reconnection. The
Field Line Universal relaXer (FLUX) code models the solar corona as
a collection of magnetic domains, represented by a quasi-Lagrangian
grid of discrete field lines (fluxons). Each fluxon represents a
defined quantity of magnetic flux and responds to magnetic tension
and pressure forces from neighboring fluxons. The model relaxes a
collection of fluxons to solve the nonlinear force-free field with a
prescribed boundary and topology. Synoptic magnetogram data are used
to drive initial fluxon placement and topology, with the output of an
observationally-driven relaxed coronal magnetic field. Open fluxons
extending from the photospheric boundary are used to compute a set
of modified one-dimensional isothermal Parker solar wind solutions,
with transonic solutions interpolated to an outer spherical boundary
grid at 21.5 solar radii for comparison with and distribution to other
heliospheric models. The FLUX model has the distinct advantages of
being computationally efficient (scaling with the complexity of the
two-dimensional boundary) and preserving connectivity to allow for
tracking the history of a bundle of magnetic flux.

---------------------------------------------------------
Title: Spectral Properties and Heavy Ion Abundances of Energetic
Particles in SEP and CIR events observed during the first two Parker
Solar Probe Orbits
Authors: Desai, M. I.; Giacalone, J.; Mitchell, D. G.; Szalay, J. R.;
Allen, R. C.; Hill, M. E.; McComas, D. J.; Christian, E. R.; Schwadron,
N.; McNutt, R. L., Jr.; Wiedenbeck, M. E.; Joyce, C.; Cohen, C.;
Cummings, A. C.; Davis, A.; Krimigis, S. M.; Leske, R. A.; Matthaeus,
W. H.; Mewaldt, R. A.; Roelof, E. C.; Labrador, A. W.; Stone, E. C.;
Gibson, S. E.; DeForest, C.
2019AGUFMSH22A..06D Altcode:
NASA's Parker Solar Probe (PSP), successfully launched on August 12
2018, has completed its first two orbits around our Sun. With perihelia
~35 Rs for both encounters, PSP has made the closest-ever observations
of the solar wind plasma, electromagnetic fields, and energetic particle
environment in the inner heliosphere. The Energetic Particle Instruments
(EPI) of the Integrated Science Investigation of the Sun (ISOIS) suite
observed a number of solar energetic particle (SEP) events associated
with flaring regions on the Sun, coronal mass ejections-driven
shocks, and local compression regions, as well as particle events
associated with corotating or stream interaction regions. This talk
surveys the spectral properties and abundances of ~0.1-2 MeV/nucleon
suprathermal H-Fe nuclei during these events and compares them with
prior observations of their counterparts observed at 1 AU. We discuss
these new PSP results in the context of our current understanding of the
origin and acceleration of suprathermal ions, the acceleration of SEPs,
and on the nature of particle transport inside Earth orbit. Finally,
we discuss the implications of these results for existing theoretical
models of the origin of suprathermal tails, and of the acceleration
and transport of SEPs and CIR-associated energetic particle events.

---------------------------------------------------------
Title: The PUNCH Bowl: Data System and Data Products for NASA's
PUNCH Mission
Authors: Thompson, B. J.; DeForest, C.; Gibson, S. E.
2019AGUFMSA11C3231T Altcode:
The Polarimeter to UNify the Corona and Heliosphere (PUNCH) mission
requires a flexible data system because the anticipated user base will
be using the data to tackle a wide range of science problems. Some will
be using PUNCH data in the classic "imager" context, while others will
be accessing the data to study solar wind dynamics. The PUNCH Bowl
provide PUNCH data, metadata, analysis tools, and higher-level PUNCH
data products, which are derived from heliospheric images to provide
additional information about structure and motion. Additionally, the
PUNCH Bowl is your access point for PUNCH Recipes: all of the tools,
code and routines that optimize the use of PUNCH data and streamline
your access. By running the "recipes" users can easily trace and
reproduce the steps used by others with minimal effort. The PUNCH Bowl
is maintained and supported by the PUNCH science team, but welcomes
contributions from users to ensure that everyone is able to easily
access all available tools and methods.

---------------------------------------------------------
Title: Novel observations of the middle corona during the 2017 total
solar eclipse
Authors: Caspi, A.; Seaton, D. B.; Tsang, C.; DeForest, C.; Bryans,
P.; Samra, J.; DeLuca, E.; Tomczyk, S.; Burkepile, J.; Gallagher,
P.; Golub, L.; Judge, P. G.; Laurent, G. T.; West, M.; Zhukov, A.
2019AGUFMSH13A..10C Altcode:
Total solar eclipses offer rare opportunities to study the middle
corona. This intriguing region contains complex interfaces and
transitions between physical regimes, but has historically been
under-observed due to the challenges of observing its dim emission so
close to the bright inner corona and blinding solar disk. The unique
circumstances of a total solar eclipse coupled with a high-altitude
observing platform provide nearly space-quality observing conditions,
including for wavelengths inaccessible by ground-based observatories,
but with availability of ground-quality resources, including high-speed,
high-resolution, wide-field coronography typically inaccessible
from space. We used the 2017 August 21 "Great American" total solar
eclipse to observe the solar corona from ~1.02 to ~3 RSun
in both visible (533.9 ± 4.75 nm) and medium-wave infrared (3-5
μm) light using stabilized telescopes on two of NASA's WB-57F
high-altitude research aircraft. This pathfinding mission utilized
existing instrumentation to evaluate the platform performance, guide
instrumentation development, and explore new discovery space for
future studies of the middle corona. We present the high-speed
(30 Hz), high-resolution (3 arcsec/pixel) visible and IR observations
obtained during the eclipse, and analysis of these observations
in the context of coronal structure and dynamics. We discuss the
limitations of the prototype data and pathways forward for future
instrumentation and missions optimized for the range of observable
parameters in the middle corona. We also discuss the benefits of
such eclipse studies to an understanding of the corona as a single,
unified system, from its origins at the solar surface to its extension
into the heliosphere, particularly within the context of a developing
multi- and inter-disciplinary research collaboration, COHERENT (the
"Corona as a Holistic Environment" Research Network).

---------------------------------------------------------
Title: Polarimeter to UNify the Corona and Heliosphere (PUNCH):
Imaging the Corona and Solar Wind as a Single System
Authors: DeForest, C. E.; Gibson, S. E.; Beasley, M.; Colaninno,
R. C.; Killough, R.; Kosmann, W.; Laurent, G. T.; McMullin, D. R.
2019AGUFMSH43B..06D Altcode:
The Polarimeter to UNify the Corona and Heliosphere (PUNCH) is a Small
Explorer mission from NASA, to understand the solar corona and young
solar wind as a complete system. It comprises four matched cameras all
operating as a "virtual instrument" to image Thomson-scattered light,
from the vantage of four separate spacecraft in Sun-synchronous
LEO. PUNCH is the first coronal and solar wind imager designed
specifically to produce three dimensional images from a single vantage
point. In addition, it will produce routine, several-times-per-day maps
of solar wind flow throughout the outer corona and inner heliosphere,
based on motion analysis of the image stream. Estimated launch date is
early 2023 for a two-year nominal mission. We present a brief overview
of the mission with emphasis on novel techniques used and exploited by
the PUNCH mission, and novel analyses enabled for the science community
by PUNCH.

---------------------------------------------------------
Title: Improving Forecast Lead Times for the Solar Wind, IMF, and
Kp Index
Authors: Elliott, H. A.; Arge, C. N.; Henney, C. J.; DeForest, C.;
McComas, D. J.; Jahn, J. M.; Dayeh, M. A.; Lepri, S. T.; Azeem, S. I.;
Crowley, G.
2019AGUFMSH32B..02E Altcode:
Solar wind and Interplanetary Magnetic Field (IMF) observations near
Earth now span several solar cycles; however, this information has
not been fully leveraged to improve forecasts. We test the ability to
produce forecast with lead times of 3-4 days for such parameters as the
Kp index; the solar wind density, speed and temperature; and the IMF
magnitude and vector components in GSM (Bx, By, and Bz) parameters. To
do so we utilize the statistical relationships amongst combinations of
these parameters. We apply these relationships to forecasts of the solar
wind speed and radial magnetic field from the combined Air Force Data
Assimilative Photospheric Flux Transport (ADAPT) and Wang-Sheeley-Arge
(WSA) models. The WSA model produces some of the most accurate solar
wind speed forecasts based on solar observations using two empirical
relationships: 1) the relationship between the solar wind speed and
magnetic field expansion factor, and 2) the relationship between solar
wind speed and the minimum angular distance between the footpoint and
open-closed field line boundary. The solar wind and IMF parameters
reflect a combination of solar source properties and changes that
occur en route owing to dynamic interactions between the fast and
slow wind. We develop relationships that distinguish contributions
from the solar sources versus those from dynamic interactions. We use
the strength of the rise and fall of the solar wind speed profile
to isolate the impact of dynamic interactions on the relationships
between solar wind and IMF parameters. Additionally, we test removing
long term trends in the solar wind and IMF parameters owing to changes
in the solar source properties by developing relationships normalized
by an average value from the prior solar rotation. We demonstrate that
contributions from the source and dynamic interactions present in the
solar wind and IMF can also be harnessed to produce long term (3-4
day) Kp forecasts. These relationships serve as individual metrics
for physical models, and when combined the relationships provide a
comprehensive baseline empirical model of the solar wind, IMF, and
Kp index.

---------------------------------------------------------
Title: Spectroscopic Constraints on the Cross-sectional Asymmetry
and Expansion of Active Region Loops
Authors: Kucera, T. A.; Young, P. R.; Klimchuk, J. A.; DeForest, C. E.
2019ApJ...885....7K Altcode:
We explore the constraints that can be placed on the dimensions of
coronal loops out of the plane of the sky by utilizing spectroscopic
observations from the Hinode/EUV Imaging Spectrometer (EIS). The
usual assumption is that loop cross sections are circular. Changes in
intensity are assumed to be the result of changing density, filling
factor, and/or point of view. In this work we instead focus on the
possibility that the loop dimensions may be changing along the line of
sight while the filling factor remains constant. We apply these ideas
to two warm (5.5≲ {log}T({{K}})&lt; 6.2) loops observed by EIS in
Active Region 11150 on 2011 February 6 with supporting observations
from Solar Dynamics Observatory's Atmospheric Imaging Assembly and
the Solar TErrestrial RElations Observatory-A's Extreme Ultraviolet
Imager. Our results are generally consistent with nonexpanding loops
but could also allow linear expansions of up to a factor of 2.5 along
a 40 Mm section of one loop and up to a factor of 3.9 in another loop,
both under the assumption that the filling factor is constant along
the loop. Expansions in the plane of the sky over the same sections of
the loops are 1.5 or less. For a filling factor of 1, the results of
the analysis are consistent with circular cross sections but also with
aspect ratios of 2 or greater. Count rate statistics are an important
part of the uncertainties, but the results are also significantly
dependent on radiometric calibration of EIS and the selection of the
loop backgrounds.

---------------------------------------------------------
Title: Constraints from Hinode/EIS on the Expansion of Active Region
Loops Along the Line of Sight
Authors: Kucera, Therese A.; Young, Peter R.; Klimchuk, James A.;
DeForest, Craig
2019AAS...23411706K Altcode:
We explore the constraints that can be placed on the dimensions of
coronal loops out of the plane of the sky by utilizing spectroscopic
observations from the Hinode/EUV Imaging Spectrometer (EIS). The
usual assumption is that loop cross sections are circular. Changes
in intensity not constant with the measured width are assumed to be
the result of changing density and/or filling factor. Here we instead
focus on the possibility that the loop dimensions may be changing along
the line of sight while the filling factor remains constant. We apply
these ideas to two cool (5.5&lt;logT&lt;6.2) loops observed by EIS with
supporting observations from Solar Dynamics Observatory's Atmospheric
Imaging Assembly (SDO/AIA) and the Solar TErrestrial RElations
Observatory-A's Extreme Ultraviolet Imager (STEREO-A/EUVI). Our
results are generally consistent with non-expanding loops, but allow
for line-of-sight expansion factors up to 3-4. The uncertainties are
sizable and are driven by count rate statistics, radiometric calibration
of EIS, and the selection of the loop backgrounds.

---------------------------------------------------------
Title: Fluxon Modeling of CMEs and the Steady Solar Wind
Authors: Lowder, Chris; Lamb, Derek; DeForest, Craig
2019AAS...23412503L Altcode:
The Field Line Universal relaXer (FLUX) code provides a framework for
modeling the evolution of the solar coronal magnetic field through the
use of fluxon structures. Each fluxon represents a piecewise-linear
analogue for magnetic field lines, and carries a finite quantity of
magnetic flux. Appropriate forces are computed and applied at vertex
points along each fluxon, allowing for relaxation to an equilibrium
state. For a given initial configuration, this allows for the study
of fieldline topology and subsequent evolution. The nature of the FLUX
model allows for enhanced efficiency when compared with grid-based MHD
models, and avoids numerical reconnection issues. We describe recent
enhancements to the FLUX code, including work with data assimilation,
calculation of steady solar wind solutions, and CME eruption triggering.

---------------------------------------------------------
Title: Denoising off-disk regions for solar knowledge discovery
Authors: Hughes, James Marcus; Monteleoni, Claire; Seaton, Daniel B.;
Bain, Hazel M.; DeForest, Craig
2019shin.confE.124H Altcode:
Machine learning methods offer great promise for image processing in
solar physics. We compare methods of denoising solar EUV images with an
emphasis on reconstructing low signal-to-noise off-disk regions. These
regions are home to the transition corona, where plasma beta goes
from low (magnetically dominated) to high (gas pressure dominated),
magnetic field topology goes from mostly closed to mostly open, and the
solar wind transitions from subsonic to supersonic. New observations
of this region could help us develop a more robust understanding of the
Sun-Heliosphere connection. Our work compares existing solar approaches
to machine learning techniques. Since we do not have noise-free images
to learn from, we employ an approach similar to Noise2Self, with the
addition of temporal and spectral information available in the solar
domain. With these new cleaned images, we perform image segmentation
to produce thematic maps, images of the Sun where different structures
such as coronal holes and active regions are identified, and test
anomaly detection algorithms with the goal of automating discovery of
scientifically interesting events.

---------------------------------------------------------
Title: COHERENT: Studying the corona as a holistic environment
Authors: Caspi, Amir; Seaton, Daniel B.; Case, Traci; Cheung, Mark;
Cranmer, Steven; DeForest, Craig E.; de Toma, Giuliana; Downs, Cooper;
Elliott, Heather; Gold, Anne U.; Longcope, Dana; Savage, Sabrina L.;
Sullivan, Susan; Viall, Nicholeen; Vourlidas, Angelos; West, Matthew J.
2019shin.confE.241C Altcode:
The solar corona and the heliosphere must be part of a single
physical system, but because the dominant physical processes change
dramatically from the magnetically-dominated low corona, through the
sparsely-observed middle corona, and into the plasma flow-dominated
outer corona and heliospheric interface, unified frameworks to study
the corona as a whole are essentially nonexistent. Understanding how
physical processes shape and drive the dynamics of the corona as a
global system, on all spatiotemporal scales, is critical for solving
many fundamental problems in solar and heliospheric physics. However,
the lack of unifying observations and models has led to a fragmentation
of the community into distinct regimes of plasma parameter space,
largely clustering around regions where existing instrumentation has
made observations widely available and where models can be sufficiently
self-contained to be tractable. We describe COHERENT, the 'Corona as a
Holistic Environment' Research Network, a focused effort to facilitate
interdisciplinary collaborative research to develop frameworks for
unifying existing and upcoming observations, theory, models, and
analytical tools to study the corona as a holistic system.

---------------------------------------------------------
Title: Modeling the Steady Solar Wind with Observationally Driven
Fluxons
Authors: Lowder, Chris; Lamb, Derek; DeForest, Craig
2019shin.confE.155L Altcode:
The Field Line Universal relaXer (FLUX) code models the solar
corona as a collection of discrete analogue magnetic domains, via a
quasi-Lagrangian grid of discrete field lines - fluxons. Each fluxon
carries a defined quantity of magnetic flux and responds to magnetic
tension and pressure forces from neighboring fluxons, relaxing to a
nonlinear force-free field in an equilibrium state. The FLUX model
scales computationally with the complexity of the two-dimensional
simulation boundary and avoids simulation grid issues, providing an
efficient tool for coronal field modeling. Assimilation of synoptic
magnetogram data drives fluxon placement, providing a relaxed coronal
field configuration out to 21.5 solar radii. Topologically open
fluxons are used to compute a set of modified isothermal Parker solar
wind solutions, which are then interpolated onto an outer spherical
boundary grid for comparison or input to solar wind models. The FLUX
model provides a flexible and efficient framework for modeling of the
coronal magnetic field and the steady solar wind.

---------------------------------------------------------
Title: Multiwavelength Study of Equatorial Coronal-hole Jets
Authors: Kumar, Pankaj; Karpen, Judith T.; Antiochos, Spiro K.; Wyper,
Peter F.; DeVore, C. Richard; DeForest, Craig E.
2019ApJ...873...93K Altcode: 2019arXiv190200922K
Jets (transient/collimated plasma ejections) occur frequently
throughout the solar corona and contribute mass/energy to the corona
and solar wind. By combining numerical simulations and high-resolution
observations, we have made substantial progress recently on determining
the energy buildup and release processes in these jets. Here we
describe a study of 27 equatorial coronal-hole jets using Solar Dynamics
Observatory/Atmospheric Imaging Assembly and Helioseismic and Magnetic
Imager observations on 2013 June 27-28 and 2014 January 8-10. Out of
27 jets, 18 (67%) are associated with mini-filament ejections; the
other nine (33%) do not show mini-filament eruptions but do exhibit
mini-flare arcades and other eruptive signatures. This indicates that
every jet in our sample involved a filament-channel eruption. From
the complete set of events, six jets (22%) are apparently associated
with tiny flux-cancellation events at the polarity inversion line, and
two jets (7%) are associated with sympathetic eruptions of filaments
from neighboring bright points. Potential-field extrapolations of
the source-region photospheric magnetic fields reveal that all jets
originated in the fan-spine topology of an embedded bipole associated
with an extreme ultraviolet coronal bright point. Hence, all our
jets are in agreement with the breakout model of solar eruptions. We
present selected examples and discuss the implications for the jet
energy buildup and initiation mechanisms.

---------------------------------------------------------
Title: New solar diagnostics enabled by novel soft x-ray imaging
spectroscopy, and future missions
Authors: Caspi, Amir; Sylwester, Janusz; Gburek, Szymon; Crowley,
Geoff; Woods, Thomas; Shih, Albert Y.; DeForest, Craig; Steslicki,
Marek; Warren, Harry; Mason, James
2018cosp...42E.525C Altcode:
Solar soft X-ray (SXR) observations provide unique diagnostics of
plasma heating, during solar flares and quiescent times. Spectrally-
and temporally-resolved measurements are crucial for understanding the
dynamics and evolution of these energetic processes; spatially-resolved
measurements are essential for understanding energy transport. A
critical observational gap exists from ∼0.2 to ∼3 keV (∼4-60
Å), where spectrally-resolved stellar observations are plentiful
but have not been routinely made for the Sun in many decades. This
energy range includes spectral lines from highly-ionized atoms with
both low and high first ionization potential (FIP), as well as thermal
free-free (bremsstrahlung) and free-bound (radiative recombination)
continua. These SXR emissions provide crucial diagnostics of plasma
temperature distributions, as well as elemental abundances that
probe plasma origins over a wide range of temperatures, that are
not available from observations at other wavelengths. A better
understanding of thermal plasma also informs our interpretation of
hard X-ray (HXR) observations of nonthermal particles, improving our
understanding of the relationships between particle acceleration,
plasma heating, and the underlying release of magnetic energy during
reconnection.We discuss a proposed small satellite pathfinder mission,
the CubeSat Imaging X-ray Solar Spectrometer (CubIXSS), to measure
spectrally- and spatially-resolved SXRs from the quiescent and
flaring Sun from a 6U CubeSat platform in low-Earth orbit during
a nominal 1-year mission. CubIXSS includes the Amptek X123-FastSDD
silicon drift detector, a low-noise, commercial off-the-shelf (COTS)
instrument enabling full-Sun SXR spectroscopy from ∼0.5 to ∼20
keV with ∼0.15 keV FWHM spectral resolution with low power, mass,
and volume requirements. Multiple detectors and tailored apertures
provide sensitivity to SXR emission from deep solar minimum to &gt;X5
flares. An X123-CdTe cadmium-telluride detector is also included for
∼5-50 keV HXR spectroscopy with ∼0.5 keV FWHM resolution. The
precise spectra from these instruments will provide detailed
measurements of the coronal temperature distribution and elemental
abundances during flares and quiescent times, and, for large flares,
context information of flare-accelerated electrons.CubIXSS also
includes a novel spectro-spatial imager - the first ever solar imager
on a CubeSat - utilizing a custom pinhole camera and Chandra-heritage
X-ray transmission diffraction grating to provide spatially- resolved,
full-Sun imaging spectroscopy from ∼0.2 to ∼10 keV (∼1-60
Å), with ∼25 arcsec and ∼0.25 Å FWHM spatial and spectral
resolutions, respectively. Additional pinholes with tailored filters
provide non-dispersed images with coarse spectral information to seed
analysis of the dispersed spectro-spatial images and for improved
sensitivity to quiescent conditions. MOXSI's unique capabilities
enable SXR spectroscopy and corresponding temperature and elemental
abundance diagnostics of individual flares and active regions over a
spectral range never before accessed by any prior solar mission.CubIXSS
is a pathfinder for larger satellites with improved resolution and
sensitivity. Through these groundbreaking new measurements, CubIXSS
and future missions will improve our physical understanding of thermal
plasma processes and impulsive energy release in the solar corona,
from quiet Sun to solar flares.

---------------------------------------------------------
Title: Tracing the Origins of the Solar Wind by Tracking Flows and
Disturbances in Coronagraph Data
Authors: Thompson, Barbara J.; Attie, Raphael; DeForest, Craig E.;
Gibson, Sarah E.; Hess Webber, Shea A.; Ireland, Jack; Kirk, Michael
S. F.; Kwon, Ryun Young; McGranaghan, Ryan; Viall, Nicholeen M.
2018shin.confE..47T Altcode:
The challenge of identifying transient motions in solar imagery has
been addressed in a number of ways. A variety of methods have been
developed to detect and characterize the motion and extent of coronal
mass ejections, for example. We discuss the adaptation of CME and
solar transient detection methods to trace smaller-scale perturbations
consistent with solar wind motions in the inner heliosphere (out to 10
RSun). We evaluate several methods, and compare the speed and structure
results to model predictions. In particular, we discuss how high-cadence
heliospheric imagery can be used to track small scale solar density
variations throughout the solar wind, serving as a proxy for in situ
velocity detection, but with global and continuous coverage.

---------------------------------------------------------
Title: Using Polarized White Light Triplets Measured by STEREO to
Isolate Internal Structure
Authors: de Koning, Curt A.; DeForest, Craig E.
2018shin.confE.199D Altcode:
On 2010 April 3, the SECCHI/COR2 coronagraphs on board the twin
NASA/STEREO spacecraft observed a coronal mass ejection (CME) in
total and polarized brightness white light. It has been suggested
that exploiting the full range of white light imagery, including the
polarization ratio, may enable reconstruction of CME internal features
as well as CME morphology; however, noisy imagery has made this promise
difficult to fulfill. Using a recently developed noise-gating process
to improve the signal-to-noise ratio in COR2, we demonstrate that we
can spatially isolate features within the CME.

---------------------------------------------------------
Title: The Highly Structured Outer Solar Corona
Authors: DeForest, C. E.; Howard, R. A.; Velli, M.; Viall, N.;
Vourlidas, A.
2018ApJ...862...18D Altcode:
We report on the observation of fine-scale structure in the outer
corona at solar maximum, using deep-exposure campaign data from the
Solar Terrestrial Relations Observatory-A (STEREO-A)/COR2 coronagraph
coupled with postprocessing to further reduce noise and thereby improve
effective spatial resolution. The processed images reveal radial
structure with high density contrast at all observable scales down to
the optical limit of the instrument, giving the corona a “woodgrain”
appearance. Inferred density varies by an order of magnitude on spatial
scales of 50 Mm and follows an f -1 spatial spectrum. The
variations belie the notion of a smooth outer corona. They are
inconsistent with a well-defined “Alfvén surface,” indicating
instead a more nuanced “Alfvén zone”—a broad trans-Alfvénic
region rather than a simple boundary. Intermittent compact structures
are also present at all observable scales, forming a size spectrum
with the familiar “Sheeley blobs” at the large-scale end. We use
these structures to track overall flow and acceleration, finding that
it is highly inhomogeneous and accelerates gradually out to the limit
of the COR2 field of view. Lagged autocorrelation of the corona has
an enigmatic dip around 10 R ⊙, perhaps pointing to new
phenomena near this altitude. These results point toward a highly
complex outer corona with far more structure and local dynamics than
has been apparent. We discuss the impact of these results on solar
and solar-wind physics and what future studies and measurements are
necessary to build upon them.

---------------------------------------------------------
Title: New Coronal Science from NASA WB-57F High-Altitude Aircraft
Observations of the 2017 Total Solar Eclipse
Authors: Caspi, Amir; DeLuca, . Edward; Tomczyk, Steven; DeForest,
Craig; Bryans, Paul; Seaton, Daniel; Tsang, Constantine
2018cosp...42E.526C Altcode:
Total solar eclipses present rare opportunities to study the
complex solar corona, down to altitudes of just a few percent of
a solar radius above the surface, using ground-based and airborne
observatories that would otherwise be dominated by the intense solar
disk and high sky brightness. Studying the corona is critical to
gaining a better understanding of physical processes that occur on
other stars and astrophysical objects, as well as understanding the
dominant driver of space weather that affects human assets at Earth and
elsewhere. For example, it is still poorly understood how the corona
is heated to temperatures of 1-2 MK globally and up to 5-10 MK above
active regions, while the underlying chromosphere is 100 times cooler;
numerous theories abound, but are difficult to constrain due to the
limited sensitivities and cadences of prior measurements. The stability
of large-scale coronal structures and the extent of their reach to the
middle and outer corona are also not well known, limited in large part
by sensitivities and fields of view of existing observations.Airborne
observations during a total eclipse provide unique advantages. By
flying in the stratosphere at altitudes of 50 kft or higher, they
avoid all weather, the seeing quality is enormously improved, and
additional wavelengths such as near-IR also become available due to
significantly reduced water absorption. An airborne observatory can
also follow the Moon's shadow, increasing the total observing time by
50% or more.We present current results of solar coronal measurements
from airborne observations of the 2017 Great American Total Solar
Eclipse using two of NASA's WB-57 high-altitude research aircraft,
each equipped with two 8.7" telescopes feeding high-sensitivity visible
(green line and nearby continuum) and medium-wave IR (3-5 {μ}m) cameras
operating at high cadence (30 Hz) with ∼3 arcsec/pixel platescale and
±3 R_{sun} fields of view. The aircraft flew along the eclipse path,
separated by ∼110 km, to observe a summed ∼7.5 minutes of totality
in both visible and MWIR. These observations enable groundbreaking
studies of high-speed coherent motion - including possible Alfvén
waves and nanojets - in the lower and middle corona that could shed
light on coronal heating processes and the formation and stability of
coronal structures. Our MWIR observations of a cool prominence and
hot coronal active region plasma will be combined with spectra from
the AIR-Spec instrument, flown concurrently on NCAR's HIAPER GV. We
review the WB-57 eclipse mission and the current results of analysis
on the visible and IR coronal measurements, along with an outlook for
future analysis and missions.

---------------------------------------------------------
Title: Characterizing Coronal Structure: Contextual Predictions
For Parker Solar Probe From Global MHD Simulations With Dynamical
Turbulence Modeling
Authors: Chhiber, Rohit; Goldstein, Mevlyn; Matthaeus, William;
Usmanov, Arcadi; Parashar, Tulasi; DeForest, Craig
2018cosp...42E.628C Altcode:
As the solar plasma flows out from the corona and transitions into the
solar wind, it transforms from a magnetically structured, subsonic,
and sub-Alfvénic regime into a supersonic and super-Alfvénic
flow dominated by hydrodynamics. Recent analysis of remote imaging
observations in solar minimum conditions by DeForest et al. (2016) has
described the early stages of this transition, which may also coincide
with the onset of large-scale turbulence in the solar wind. Here we
extend this analysis to global magnetohydrodynamic simulation of the
corona and solar wind based on inner boundary conditions that emulate
solar minimum, in anticipation of the first phase of Parker Solar
Probe (PSP) observations, which are expected during solar minimum
as well. Taken together with the imaging analysis, the simulation
results provide more detailed expectations for locations of the Alfvén
critical surface and the first plasma beta unity surface moving from
the corona into the dynamically active solar wind. The turbulence
parameters computed from the simulations also enable estimations of the
characteristic scales at which in-situ turbulence may influence the
dynamics of the solar wind. Estimations of relevant parameters along
a simulated PSP trajectory are presented. Issues pertaining to the use
of Taylor's frozen-in hypothesis with PSP perihelion data are discussed.

---------------------------------------------------------
Title: Multiwavelength Study of 24 Equatorial Coronal-Hole Jets
Authors: Kumar, Pankaj; Antiochos, Spiro; Karpen, Judy; DeForest,
Craig; DeVore, C. Richard; Wyper, Peter
2018cosp...42E1863K Altcode:
We studied 24 equatorial coronal-hole (ECH) jets using SDO/AIA and
HMI observations on 27-28 June 2013 and 8-10 January 2014. Out of 24
jets (i) 16 jets (67%) are associated with mini-filament eruptions;
(ii) 8 jets (34%) are triggered without mini-filament eruptions
but with mini-flare arcades and other CME-like signatures; (iii)
5 jets (21%) are apparently associated with tiny flux-cancellation
events at the polarity inversion line; (iv) 3 events are associated
with sympathetic eruptions of filaments from neighboring jet source
regions. The potential field extrapolations of the source regions
reveal that almost all jets occurred in the fan-spine topology, and
most of the events are in agreement with the breakout model of solar
jets. We will present selected examples of each type, and discuss the
implications for the jet energy-buildup and initiation mechanisms.

---------------------------------------------------------
Title: Tracking Flows and Disturbances in Coronagraph Data
Authors: Thompson, Barbara J.; Attie, Raphael; DeForest, Craig E.;
Gibson, Sarah E.; Hess Webber, Shea A.; Inglis, Anfew R.; Ireland,
Jack; Kirk, Michael S.; Kwon, RyunYoung; Viall, Nicholeen M.
2018tess.conf30922T Altcode:
The challenge of identifying transient motions in solar imagery has
been addressed in a number of ways. A variety of methods have been
developed to detect and characterize the motion and extent of coronal
mass ejections, for example. We discuss the adaptation of CME and
solar transient detection methods to trace smaller-scale perturbations
consistent with solar wind motions in the inner heliosphere (over 10
RSun). We evaluate several methods, and compare the speed and structure
results to model predictions. In particular, we discuss how high-cadence
heliospheric imagery can be used to track small scale solar density
variations throughout the solar wind, serving as a proxy for in situ
velocity detection, but with global and continuous coverage.

---------------------------------------------------------
Title: Turtles All The Way Down: The finely structured outer corona,
and its implications for PSP
Authors: DeForest, Craig E.; Howard, Russell A.; Velli, Marco C. M.;
Viall, Nicholeen M.; Vourlidas, Angelos
2018tess.conf30928D Altcode:
Based on optical resolution of the starfield with SOHO/LASCO,
STEREO/COR, and other coronagraphs, there is widespread intuition that
the solar corona becomes more smooth with altitude. This is an optical
illusion, caused by the interplay between signal-to-noise ratio (SNR)
and feature size in typical coronal images. Processed, low-noise,
deep-field COR2 images of the outer corona reveal rich structure at
all observable scales, with surprising time variability and very short
spatial correlation scales under 50 Mm, at altitudes near 10 Rs. This
has deep implications not only for the solar wind and outer coronal
physics, but also for the types of structure that Parker Solar Probe
will encounter. We will present and discuss the fundamental result,
and explore its implications for in-situ science and required context
imaging from PSP. We will also make specific predictions about the
environment PSP will encounter at solar altitudes of 10-15 Rs.

---------------------------------------------------------
Title: Eclipse Science from 50,000 Feet: New Coronal Results from
NASA WB-57F High-Altitude Aircraft Observations of the 2017 Total
Solar Eclipse
Authors: Caspi, Amir; Tsang, Constantine; Seaton, Daniel B.; DeForest,
Craig; Bryans, Paul; DeLuca, Edward; Tomczyk, Steven; Burkepile,
Joan; Casey, Thomas Anthony; Collier, John; Darrow, Donald DD; Del
Rosso, Dominic; Durda, Daniel D.; Gallagher, Peter; Gascar, Jasmine;
Golub, Leon; Jacyna, Matthew; Johnson, David DJ; Judge, Philip G.;
Klemm, Cary; Laurent, Glenn Thomas; Lewis, Johanna; Mallini, Charles;
Parent, Thomas Duster; Propp, Timothy; Steffl, Andrew; Warner, Jeff;
West, Matthew John; Wiseman, John; Yates, Mallory; Zhukov, Andrei
2018tess.conf31302C Altcode:
Total solar eclipses present rare opportunities to study the complex
solar corona, down to altitudes of just a few percent of a solar
radius above the surface. Studying the corona is critical to gaining
a better understanding of the dominant driver of space weather that
affects human assets on Earth and elsewhere. For example, it is still
poorly understood how the corona is heated to temperatures of 1-2 MK
globally and up to 5-10 MK above active regions, while the underlying
chromosphere is 100 times cooler. The stability of large-scale coronal
structures and the extent of their reach to the middle and outer corona
are also not well known, limited in large part by sensitivities and
fields of view of existing observations. Airborne observations
during a total eclipse provide unique advantages. By flying in the
stratosphere at altitudes of 50 kft or higher, they avoid all weather,
the seeing quality is enormously improved, and additional wavelengths
such as near-IR also become available due to significantly reduced
water absorption. An airborne observatory can also follow the Moon's
shadow, increasing the total observing time by 50% or more. We
present current results of solar coronal measurements from airborne
observations of the 2017 Great American Total Solar Eclipse using two
of NASA's WB-57 high-altitude research aircraft, each equipped with
two 8.7-inch telescopes feeding high-sensitivity visible (green line
and nearby continuum) and medium-wave IR (3-5 μm) cameras operating
at high cadence (30 Hz) with ∼3 arcsec/pixel platescale and ±3
Rsun fields of view. The two aircraft flew along the eclipse
path, separated by ∼110 km, to observe a total of ∼7.5 minutes
of totality in both visible and MWIR. These observations enable
groundbreaking studies of high-speed coherent motion - including
possible Alfvén waves and nanojets - in the lower and middle corona
that could shed light on coronal heating processes and the formation
and stability of coronal structures. Our MWIR observations of a cool
prominence and hot coronal active region plasma will be combined with
spectra from the AIR-Spec instrument, flown concurrently on NCAR's
HIAPER GV. We review the WB-57 eclipse mission and the current results
of analysis on the visible and IR coronal measurements, along with an
outlook for future analysis and missions.

---------------------------------------------------------
Title: Statistical Study of 24 Equatorial Coronal-Hole Jets
Authors: Kumar, Pankaj; Karpen, Judith T.; Antiochos, Spiro K.;
Fraser Wyper, Peter; DeVore, C. Richard; DeForest, Craig
2018tess.conf40805K Altcode:
To understand the trigger mechanisms of coronal-hole jets, we analysed
24 equatorial coronal-hole (ECH) jets using SDO/AIA and HMI observations
during 2013-2014. Out of 24 jets (i) 16 jets (67%) are associated
with mini-filament eruptions; (ii) 8 jets (34%) are triggered without
mini-filament eruptions but with mini-flare arcades and other CME-like
signatures; (iii) 5 jets (21%) are apparently associated with tiny
flux-cancellation events at the polarity inversion line; (iv) 3 events
are associated with sympathetic eruptions of filaments from neighboring
jet source regions. The potential field extrapolations of the source
regions reveal that almost all jets occurred in the fan-spine topology,
and most of the events are in agreement with the breakout model of solar
jets. We will present selected examples of each type, and discuss the
implications for the jet energy-buildup and initiation mechanisms.

---------------------------------------------------------
Title: Unifying the Solar Corona and Heliosphere
Authors: DeForest, Craig E.
2018tess.conf31701D Altcode:
The corona and solar wind are parts of a single unified system. For
at least five decades, solar coronal physics and solar wind physics
have been divided by the instrumentation that each field uses to study
essentially the same plasma. Solar wind studies have used primarily in
situ sampling such as local measurement of magnetic field, solar wind
parameters, and compisition, which reveal great detail and physical
"ground truth" over a tiny cross-section of the solar wind. Solar
coronal studies have used primarily remote imaging such as coronagraphic
movies, which reveal large-scale evolution and structure, at a cost of
limiting measurements to (in most cases) a photometric measure of the
line-of-sight electron density. Recent advances in in-situ sampling
(the development of \emph{Parker Solar Probe} and revisitation of data
from the \emph{Helios} mission) enable direct sampling of the corona
using the technology formerly applied to the solar wind. In parallel,
advances in high-sensitivity imaging have permitted direct imaging of
the solar wind itself as it forms. I will recap the state of high
sensitivity coronal imaging, which demonstrates that the phenomenology
and dynamics of the outer corona (and its transition to the solar wind)
are every bit as rich as the dynamics of the inner corona. Developing
a fully unified understanding of this region requires not only direct
sampling of the microphysics by Parker Solar Probe, but also remote
measurement of the cross-scale physics of this turbulent, complex
interface between the star and its environs. This understanding is
central both to scientific understanding of the heliosphere, and also
to improving space weather prediction, because the largest source of
uncertainty in space weather at Earth is the environment through which
CMEs and other disturbances propagate. Deep-field, polarized imaging
of the outer corona and young solar wind are technically feasible and
will reveal the "missing link" of the young solar wind, in its full
global and cross-scale complexity.

---------------------------------------------------------
Title: Towards Fluxon Modeling of CMEs and the Steady Solar Wind
Authors: Lowder, Chris; Lamb, Derek A.; DeForest, Craig
2018tess.conf10416L Altcode:
The Field Line Universal relaXer (FLUX) code provides a framework
for modeling MHD evolution in the solar corona. 'Fluxons' are
the piecewise-linear analogue for magnetic field lines, composed of
segments connecting individual vertices. Each fluxon carries a finite
quantity of magnetic flux. Within the simulation, forces are calculated
and applied to vertex points, relaxing to an equilibrium state. With
physical quantities only defined along the fluxons, interpolation is
required for calculating plasma parameters at arbitrary locations, or
for interfacing with grid-based simulations. We describe recent changes
to this interpolation code that result in improved interpolation results
with minimal impact on computational cost. With these modifications,
FLUX is a more robust tool for solar wind modeling and studying the
magnetic structure of solar coronal eruptions.

---------------------------------------------------------
Title: Using Global Simulations to make Contextual Predictions for
Parker Solar Probe: Critical Surfaces and Turbulence
Authors: Chhiber, Rohit; Usmanov, Arcadi V.; Matthaeus, William H.;
Parashar, Tulasi; Goldstein, Melvyn L.; DeForest, Craig
2018tess.conf31203C Altcode:
The Parker Solar Probe (PSP) mission is scheduled for a summer 2018
launch, with the goal of exploring regions of the solar wind that are of
crucial importance in establishing the heliosphere. The spacecraft will
approach the Sun closer than any prior mission has, and will present
unique and unprecedented opportunities to characterize the physical
properties of the solar corona. As the PSP makes its high-resolution
in-situ measurements, a knowledge of the large-scale environment
of these observations will be of vital importance. In particular,
one would like to have an indication of the locations of the critical
surfaces that characterize the transformation of the coronal plasma from
a magnetically structured, subsonic, and sub-Alfvénic regime into a
supersonic and super-Alfvénic flow dominated by hydrodynamics. These
surfaces - the sonic surface, the Alfvén surface, and the first
plasma beta unity surface - may be associated with several phenomena
of interest to PSP science, ranging from preferential heating of
alpha particles to the onset of large-scale turbulence. Here we
present results from global three-dimensional magnetohydrodynamic (MHD)
simulations of the solar wind that we have used to localize the critical
surfaces and investigate the flow in propinquitous regions. Effects of
solar activity are incorporated by varying source magnetic dipole tilts
and by employing magnetogram-based boundary conditions. A small-scale
MHD turbulence model is self-consistently and dynamically coupled to the
bulk flow equations, enabling investigation of turbulence properties
of the flow in the vicinity of critical regions. The simulation
results are compared with a variety of remote sensing observations. A
simulated PSP trajectory is used to provide contextual predictions for
the spacecraft in terms of the computed critical surfaces. We also
examine the turbulence environment the PSP is likely to find itself
in, and discuss issues pertaining to the use of Taylor's frozen-in
hypothesis with the spacecraft's in-situ observations.

---------------------------------------------------------
Title: A Novel Soft X-ray Slitless Imaging Spectrograph for Unique
Diagnostics of Hot Coronal Plasma
Authors: Caspi, Amir; Shh, Albert Y.; Warren, Harry; Woods, Thomas
N.; Mason, James Paul; Steslicki, MArek; Gburek, Szymon; Sylwester,
Janusz; DeForest, Craig; Schwartz, Richard; Crowley, Geoff
2018tess.conf41006C Altcode:
Solar soft X-ray (SXR) observations from ∼0.2 to ∼3 keV
(∼4-60 Å), during both solar flares and quiescent times, provide
crucial diagnostics that are not available from observations at other
wavelengths. Specifically, SXRs reveal plasma temperature distributions,
as well as elemental abundances that probe plasma origins over a wide
range of temperatures. Spectrally- and temporally-resolved measurements
are essential for understanding the dynamics and evolution of these
energetic processes; spatially-resolved measurements are essential
for understanding energy transport. The NGSPM study calls out an X-ray
spectroscopic imager (T-10) as a high-priority instrument, in particular
with a spectral resolution of better than 100 eV for SXR emission
lines. We describe a novel approach for a spectro-spatial imager
- combining a pinhole camera with a X-ray transmission diffraction
grating - that can achieve the required combination of spectral and
angular resolutions at SXR energies. Such an instrument has already
been demonstrated as a protoype on a sounding-rocket flight and can be
proven thoroughly on a small satellite, specifically as part of the
instrument complement of the proposed CubeSat Imaging X-ray Solar
Spectrometer (CubIXSS) mission. CubIXSS will measure spectrally-
and spatially-resolved SXRs from ~1 to 60 Å (~0.2-10 keV) with ~0.25
Å and ~25 arcsec FWHM resolutions, respectively, from the quiescent
and flaring Sun from a 6U CubeSat platform in low-Earth orbit during
a nominal 1-year mission. Accordingly, CubIXSS is a pathfinder for
larger satellites with improved resolution (&lt;0.1 Å, ~few arcsec)
and sensitivity, that could be integrated with focusing optics if
desired. Through these groundbreaking new measurements, CubIXSS and
future missions will improve our physical understanding of thermal
plasma processes and impulsive energy release in the solar corona,
from quiet Sun to solar flares.

---------------------------------------------------------
Title: Weakened Magnetization and Onset of Large-scale Turbulence
in the Young Solar Wind—Comparisons of Remote Sensing Observations
with Simulation
Authors: Chhiber, Rohit; Usmanov, Arcadi V.; DeForest, Craig E.;
Matthaeus, William H.; Parashar, Tulasi N.; Goldstein, Melvyn L.
2018ApJ...856L..39C Altcode:
Recent analysis of Solar-Terrestrial Relations Observatory (STEREO)
imaging observations have described the early stages of the development
of turbulence in the young solar wind in solar minimum conditions. Here
we extend this analysis to a global magnetohydrodynamic (MHD) simulation
of the corona and solar wind based on inner boundary conditions,
either dipole or magnetogram type, that emulate solar minimum. The
simulations have been calibrated using Ulysses and 1 au observations,
and allow, within a well-understood context, a precise determination of
the location of the Alfvén critical surfaces and the first plasma beta
equals unity surfaces. The compatibility of the the STEREO observations
and the simulations is revealed by direct comparisons. Computation of
the radial evolution of second-order magnetic field structure functions
in the simulations indicates a shift toward more isotropic conditions at
scales of a few Gm, as seen in the STEREO observations in the range
40-60 R ⊙. We affirm that the isotropization occurs
in the vicinity of the first beta unity surface. The interpretation
based on early stages of in situ solar wind turbulence evolution is
further elaborated, emphasizing the relationship of the observed length
scales to the much smaller scales that eventually become the familiar
turbulence inertial range cascade. We argue that the observed dynamics
is the very early manifestation of large-scale in situ nonlinear
couplings that drive turbulence and heating in the solar wind.

---------------------------------------------------------
Title: Evidence for the Magnetic Breakout Model in an Equatorial
Coronal-hole Jet
Authors: Kumar, Pankaj; Karpen, Judith T.; Antiochos, Spiro K.; Wyper,
Peter F.; DeVore, C. Richard; DeForest, Craig E.
2018ApJ...854..155K Altcode: 2018arXiv180108582K
Small, impulsive jets commonly occur throughout the solar corona,
but are especially visible in coronal holes. Evidence is mounting that
jets are part of a continuum of eruptions that extends to much larger
coronal mass ejections and eruptive flares. Because coronal-hole jets
originate in relatively simple magnetic structures, they offer an ideal
testbed for theories of energy buildup and release in the full range
of solar eruptions. We analyzed an equatorial coronal-hole jet observed
by the Solar Dynamics Observatory (SDO)/AIA on 2014 January 9 in which
the magnetic-field structure was consistent with the embedded-bipole
topology that we identified and modeled previously as an origin of
coronal jets. In addition, this event contained a mini-filament,
which led to important insights into the energy storage and release
mechanisms. SDO/HMI magnetograms revealed footpoint motions in the
primary minority-polarity region at the eruption site, but show
negligible flux emergence or cancellation for at least 16 hr before
the eruption. Therefore, the free energy powering this jet probably
came from magnetic shear concentrated at the polarity inversion line
within the embedded bipole. We find that the observed activity sequence
and its interpretation closely match the predictions of the breakout
jet model, strongly supporting the hypothesis that the breakout model
can explain solar eruptions on a wide range of scales.

---------------------------------------------------------
Title: Instruments for Deep Space Weather Prediction and Science
Authors: DeForest, C. E.; Laurent, G.
2018LPICo2063.3176D Altcode:
We discuss remote space weather monitoring system concepts that could
mount on the Deep Space Gateway and provide predictive capability
for space weather events including SEP events and CME crossings,
and advance heliophysics of the solar wind.

---------------------------------------------------------
Title: Evidence for the Magnetic Breakout Model in AN Equatorial
Coronal-Hole Jet
Authors: Kumar, P.; Karpen, J.; Antiochos, S. K.; Wyper, P. F.;
DeVore, C. R.; DeForest, C. E.
2017AGUFMSH52B..02K Altcode:
We analyzed an equatorial coronal-hole jet observed by Solar Dynamic
Observatory (SDO)/AtmosphericImaging Assembly (AIA). The source-region
magnetic field structure is consistent withthe embedded-bipole topology
that we identified and modeled previously as a source of coronal
jets. Theinitial brightening was observed below a sigmoid structure
about 25 min before the onset of an untwisting jet.A circular magnetic
flux rope with a mini-filament rose slowly at the speed of ∼15 km/s ,
then accelerated(∼126 km/s) during the onset of explosive breakout
reconnection. Multiple plasmoids, propagating upward(∼135 km/s)
and downward (∼55 km/s ), were detected behind the rising flux rope
shortly before andduring explosive breakout reconnection. The jet
was triggered when the rising flux rope interacted with theoverlying
magnetic structures near the outer spine. This event shows a clear
evidence of reconnection not onlybelow the flux rope but also a breakout
reconnection above the flux rope. During the breakout reconnection,we
observed heating of the flux rope, deflection of loops near the
spine, and formation of multiple ribbons.The explosive breakout
reconnection destroyed the flux rope that produced an untwisting jet
with a speed of∼380 km/s . HMI magnetograms reveal the shear motion
at theeruption site, but do not show any significant flux emergence
or cancellation during or 2 hours before theeruption. Therefore, the
free energy powering this jet most likely originated in magnetic shear
concentratedat the polarity inversion line within the embedded bipole-a
mini-filament channel-possibly created by helicitycondensation. The
result of of a statistical study of multiple jets will also be
discussed.

---------------------------------------------------------
Title: Chasing the Great American 2017 Total Solar Eclipse: Coronal
Results from NASA's WB-57F High-Altitude Research Aircraft
Authors: Caspi, A.; Tsang, C.; DeForest, C. E.; Seaton, D. B.; Bryans,
P.; Burkepile, J.; Casey, T. A.; Collier, J.; Darrow, D.; DeLuca,
E.; Durda, D. D.; Gallagher, P.; Golub, L.; Judge, P. G.; Laurent,
G. T.; Lewis, J.; Mallini, C.; Parent, T.; Propp, T.; Steffl, A.;
Tomczyk, S.; Warner, J.; West, M. J.; Wiseman, J.; Zhukov, A.
2017AGUFMSH24A..05C Altcode:
Total solar eclipses present rare opportunities to study the complex
solar corona, down to altitudes of just a few percent of a solar
radius above the surface, using ground-based and airborne observatories
that would otherwise be dominated by the intense solar disk and high
sky brightness. Studying the corona is critical to gaining a better
understanding of physical processes that occur on other stars and
astrophysical objects, as well as understanding the dominant driver of
space weather that affects human assets at Earth and elsewhere. For
example, it is still poorly understood how the corona is heated to
temperatures of 1-2 MK globally and up to 5-10 MK above active regions,
while the underlying chromosphere is 100 times cooler; numerous theories
abound, but are difficult to constrain due to the limited sensitivities
and cadences of prior measurements. The origins and stability of coronal
fans, and the extent of their reach to the middle and outer corona,
are also not well known, limited in large part by sensitivities and
fields of view of existing observations. Airborne observations during
the eclipse provide unique advantages; by flying in the stratosphere
at altitudes of 50 kft or higher, they avoid all weather, the seeing
quality is enormously improved, and additional wavelengths such as
near- IR also become available due to significantly reduced water
absorption. For an eclipse, an airborne observatory can also follow the
shadow, increasing the total observing time by 50% or more. We present
results of solar coronal measurements from airborne observations of
the 2017 Great American Total Solar Eclipse using two of NASA's WB-57
high-altitude research aircraft, each equipped with two 8.7" telescopes
feeding high-sensitivity visible (green-line) and medium-wave IR (3-5
μm) cameras operating at high cadence (30 Hz) with 3 arcsec/pixel
platescale and ±3 R_sun fields of view. The aircraft flew along the
eclipse path, separated by 110 km, to observe a summed 7.5 minutes of
totality in both visible and NIR, enabling groundbreaking studies of
high-speed wave motions and nanojets in the lower corona, the structure
and extent of coronal fans, and constraints on a potential primordial
dust ring around the Sun. We review the mission, and the results of
analysis on the visible and IR coronal measurements.

---------------------------------------------------------
Title: Planetary Science from NASA's WB-57 Canberra High Altitude
Research Aircraft During the Great American Eclipse of 2017
Authors: Tsang, C.; Caspi, A.; DeForest, C. E.; Durda, D. D.; Steffl,
A.; Lewis, J.; Wiseman, J.; Collier, J.; Mallini, C.; Propp, T.;
Warner, J.
2017AGUFMSH13B2482T Altcode:
The Great American Eclipse of 2017 provided an excellent opportunity for
heliophysics research on the solar corona and dynamics that encompassed
a large number of research groups and projects, including projects
flown in the air and in space. Two NASA WB-57F Canberra high altitude
research aircraft were launched from NASA's Johnson Space Center,
Ellington Field into the eclipse path. At an altitude of 50,000ft,
and outfitted with visible and near-infrared cameras, these aircraft
provided increased duration of observations during eclipse totality,
and much sharper images than possible on the ground. Although the
primary mission goal was to study heliophysics, planetary science
was also conducted to observe the planet Mercury and to search for
Vulcanoids. Mercury is extremely challenging to study from Earth. The
2017 eclipse provided a rare opportunity to observe Mercury under ideal
astronomical conditions. Only a handful of near-IR thermal images
of Mercury exist, but IR images provide critical surface property
(composition, albedo, porosity) information, essential to interpreting
lower resolution IR spectra. Critically, no thermal image of Mercury
currently exists. By observing the nightside surface during the 2017
Great American Eclipse, we aimed to measure the diurnal temperature
as a function of local time (longitude) and attempted to deduce the
surface thermal inertia integrated down to a few-cm depth below the
surface. Vulcanoids are a hypothesized family of asteroids left
over from the formation of the solar system, in the dynamically
stable orbits between the Sun and Mercury at 15-45 Rs (4-12° solar
elongation). Close proximity to the Sun, plus their small theoretical
sizes, make Vulcanoid searches rare and difficult. The 2017 eclipse
was a rare opportunity to search for Vulcanoids. If discovered these
unique, highly refractory and primordial bodies would have a significant
impact on our understanding of solar system formation. Only a handful
of deep searches have been conducted. Our observations will only be the
second time ever a search for Vulcanoids will have been conducted in
the NIR. In this presentation, I will review our NASA flight program,
and focus on the planetary science observations that came from the
Great American Eclipse of 2017.

---------------------------------------------------------
Title: 3D Polarized Imaging of Coronal Mass Ejections: Chirality of
a CME
Authors: DeForest, C. E.; de Koning, C. A.; Elliott, H. A.
2017ApJ...850..130D Altcode:
We report on a direct polarimetric determination of the chirality of a
coronal mass ejection (CME), using the physics of Thomson scattering
applied to synoptic polarized images from the Solar Terrestrial
Relations Observatories/COR2 coronagraph. We confirmed the determination
using in situ magnetic field measurements of the same CME with the
ACE spacecraft. CME chirality is related to the helicity ejected
from the solar corona along with the mass and field entrained in the
CME. It is also important to prediction of the space-weather-relevant Z
component of the CME magnetic field. Hence, remote measurement of CME
chirality is an important step toward both understanding CME physics
and predicting geoeffectiveness of individual CMEs. The polarimetric
properties of Thomson scattering are well known and can, in principle,
be used to measure the 3D structure of imaged objects in the solar
corona and inner heliosphere. However, reduction of that principle
to practice has been limited by the twin difficulties of background
subtraction and the signal-to-noise ratio in coronagraph data. Useful
measurements of the 3D structure require relative photometry at a few
percent precision level in each linear polarization component of the K
corona. This corresponds to a relative photometric precision of order
10-4 in direct images of the sky before subtraction of the
F corona and related signal. Our measurement was enabled by recent
developments in signal processing, which enable a better separation of
the photometric signal from noise in the synoptic COR2 data. We discuss
the relevance of this demonstration measurement to future instrument
requirements, and to the future measurements of 3D structures in CMEs
and other solar wind features.

---------------------------------------------------------
Title: Global Fluxon Modeling of the Solar Corona and Inner
Heliosphere
Authors: Lamb, D. A.; DeForest, C. E.
2017AGUFMSH11B2440L Altcode:
The fluxon approach to MHD modeling enables simulations of low-beta
plasmas in the absence of undesirable numerical effects such as
diffusion and magnetic reconnection. The magnetic field can be modeled
as a collection of discrete field lines ("fluxons") containing a set
amount of magnetic flux in a prescribed field topology. Due to the
fluxon model's pseudo-Lagrangian grid, simulations can be completed in
a fraction of the time of traditional grid-based simulations, enabling
near-real-time simulations of the global magnetic field structure
and its influence on solar wind properties. Using SDO/HMI synoptic
magnetograms as lower magnetic boundary conditions, and a separate
one-dimensional fluid flow model attached to each fluxon, we compare
the resulting fluxon relaxations with other commonly-used global models
(such as PFSS), and with white-light images of the corona (including
the August 2017 total solar eclipse). Finally, we show the computed
magnetic field expansion ratio, and the modeled solar wind speed near
the coronal-heliospheric transition. Development of the fluxon MHD
model FLUX (the Field Line Universal relaXer), has been funded by
NASA's Living with a Star program and by Southwest Research Institute.

---------------------------------------------------------
Title: Characterizing coronal structure: Combining remote sensing
observations with global MHD modeling to make predictions for Parker
Solar Probe and Solar Orbiter missions
Authors: Chhiber, R.; Usmanov, A. V.; Matthaeus, W. H.; DeForest,
C. E.; Parashar, T.; Goldstein, M. L.
2017AGUFMSH23D2690C Altcode:
As the solar plasma flows out from the corona and transitions into the
solar wind, it transforms from a magnetically structured, subsonic,
and sub-Alfvénic regime into a supersonic and super-Alfvénic
flow dominated by hydrodynamics. Recent analysis of remote imaging
observations in solar minimum conditions by DeForest et al. (2016)
have described the early stages of this transition. Here we extend
this analysis to global magnetohydrodynamics simulation of the corona
and solar wind based on inner boundary conditions that emulate solar
minimum, in anticipation of the first phase of Parker Solar Probe (PSP)
observations, which are expected during solar minimum as well. Taken
together with the imaging analysis, the simulation results provide more
detailed expectations for locations of the Alfvén critical surface
and the first plasma beta unity surface moving from the corona into
the dynamically active solar wind. The turbulence parameters computed
from the simulations also enable estimations of the characteristic
scales at which in-situ turbulence may influence the dynamics of the
solar wind. Estimations of relevant parameters along a simulated PSP
trajectory is presented. This multi-faceted approach may be useful
in the context of the upcoming Parker Solar Probe and Solar Orbiter
missions, which will explore, for the first time, this transition in
the inner heliosphere.

---------------------------------------------------------
Title: Using STEREO Polarized White Light Triplets to Reconstruct
Features in a CME
Authors: de Koning, C. A.; DeForest, C. E.
2017AGUFMSH22B..05D Altcode:
On 2010 April 3, the twin NASA/STEREO spacecraft observed a coronal
mass ejection (CME) in total and polarized brightness white light
using the SECCHI/COR2 corornagraphs. It has been suggested previously
that exploiting the full range of white light imagery may enable
reconstruction of a CME's internal features; however, noisy imagery
has made this promise difficult to fulfill. Using a recently developed
noise-gating process to improve the signal-to-noise ratio in COR2,
we demonstrate that we can spatially isolate features within a CME. In
particular, we measure the orientation of a white-light cavity. Since
such a cavity is often associated with a CME flux rope, we suggest
that combining total brightness measurements and degree of polarization
imagery can be used to investigate CME flux ropes.

---------------------------------------------------------
Title: Mapping The Territory: What Current Remote Sensing Tells Us
To Expect For PSP
Authors: DeForest, C. E.; McComas, D. J.; Vourlidas, A.; Howard, R.
2017AGUFMSH21C..06D Altcode:
Remote sensing with current coronagraphs affords the best current
estimate of plasma conditions PSP will encounter. Over the past few
years, analyses of the synoptic data sets from the STEREO/COR2 and
STEREO/HI1 imagers have yielded rough locations for critical loci such
as the Alfvén and β=1 surfaces. We now present new results from
the deepest-field coronagraph sequence made to date: the STEREO-A
deep-field campaign. Recently-developed noise reduction techniques
and the unique deep-exposure data set reveal small scale motions and
fluctuations throughout the visible corona and give new insight into
the structure of the outer corona.

---------------------------------------------------------
Title: Noise Gating Solar Images
Authors: DeForest, Craig; Seaton, Daniel B.; Darnell, John A.
2017SPD....48.0601D Altcode:
I present and demonstrate a new, general purpose post-processing
technique, "3D noise gating", that can reduce image noise by an order
of magnitude or more without effective loss of spatial or temporal
resolution in typical solar applications.Nearly all scientific images
are, ultimately, limited by noise. Noise can be direct Poisson
"shot noise" from photon counting effects, or introduced by other
means such as detector read noise. Noise is typically represented
as a random variable (perhaps with location- or image-dependent
characteristics) that is sampled once per pixel or once per resolution
element of an image sequence. Noise limits many aspects of image
analysis, including photometry, spatiotemporal resolution, feature
identification, morphology extraction, and background modeling
and separation.Identifying and separating noise from image signal
is difficult. The common practice of blurring in space and/or time
works because most image "signal" is concentrated in the low Fourier
components of an image, while noise is evenly distributed. Blurring
in space and/or time attenuates the high spatial and temporal
frequencies, reducing noise at the expense of also attenuating image
detail. Noise-gating exploits the same property -- "coherence" -- that
we use to identify features in images, to separate image features from
noise.Processing image sequences through 3-D noise gating results in
spectacular (more than 10x) improvements in signal-to-noise ratio, while
not blurring bright, resolved features in either space or time. This
improves most types of image analysis, including feature identification,
time sequence extraction, absolute and relative photometry (including
differential emission measure analysis), feature tracking, computer
vision, correlation tracking, background modeling, cross-scale
analysis, visual display/presentation, and image compression.I will
introduce noise gating, describe the method, and show examples from
several instruments (including SDO/AIA , SDO/HMI, STEREO/SECCHI,
and GOES-R/SUVI) that explore the benefits and limits of the technique.

---------------------------------------------------------
Title: First results from the NASA WB-57 airborne observations of
the Great American 2017 Total Solar Eclipse
Authors: Caspi, Amir; Tsang, Constantine; DeForest, Craig; Seaton,
Daniel B.; Bryans, Paul; Tomczyk, Steven; Burkepile, Joan; Judge,
Phil; DeLuca, Edward E.; Golub, Leon; Gallagher, Peter T.; Zhukov,
Andrei; West, Matthew; Durda, Daniel D.; Steffl, Andrew J.
2017SPD....4810701C Altcode:
Total solar eclipses present rare opportunities to study the complex
solar corona, down to altitudes of just a few percent of a solar
radius above the surface, using ground-based and airborne observatories
that would otherwise be dominated by the intense solar disk and high
sky brightness. Studying the corona is critical to gaining a better
understanding of physical processes that occur on other stars and
astrophysical objects, as well as understanding the dominant driver of
space weather that affects human assets at Earth and elsewhere. For
example, it is still poorly understood how the corona is heated to
temperatures of 1-2 MK globally and up to 5-10 MK above active regions,
while the underlying chromosphere is 100 times cooler; numerous theories
abound, but are difficult to constrain due to the limited sensitivities
and cadences of prior measurements. The origins and stability of coronal
fans, and the extent of their reach to the middle and outer corona,
are also not well known, limited in large part by sensitivities and
fields of view of existing observations.Airborne observations during
the eclipse provide unique advantages; by flying in the stratosphere
at altitudes of 50 kft or higher, they avoid all weather, the seeing
quality is enormously improved, and additional wavelengths such
as near-IR also become available due to significantly reduced water
absorption. For an eclipse, an airborne observatory can also follow the
shadow, increasing the total observing time by 50% or more.We present
the first results from airborne observations of the 2017 Great American
Total Solar Eclipse using two of NASA's WB-57 research aircraft, each
equipped with two 8.7" telescopes feeding high-sensitivity visible
(green-line) and near-IR (3-5 µm) cameras operating at high cadence
(30 Hz) with ~3 arcsec/pixel platescale and ±3 R_sun fields of
view. The aircraft will fly along the eclipse path, separated by ~90
km, to observe a summed ~8 minutes of totality in both visible and
NIR, enabling groundbreaking studies of high-speed wave motions and
nanojets in the lower corona, the structure and extent of coronal fans,
and constraints on a potential primordial dust ring around the Sun.

---------------------------------------------------------
Title: Solar Jetlets and Plumes
Authors: DeForest, Craig; Antiochos, Spiro K.; DeVore, C. Richard;
Karpen, Judith T.; Kumar, Pankaj; Raouafi, Nour-Eddine; Roberts,
Merrill; Uritsky, Vadim; Wyper, Peter
2017SPD....4830401D Altcode:
We present results of a careful deep-field (low-noise) analysis of
evolution and structure of solar plumes using multiple wavelength
channels from SDO/AIA. Using new noise-reduction techniques on
SDO/AIA images, we reveal myriad small, heating events that appear
to be the primary basis of plume formation and sustenance. These
events ("jetlets") comprise a dynamic tapestry that forms the more
distributed plume itself. We identify the "jetlets" with ejecta that
have been previously observed spectroscopically, and distinguish
them from the quasi-periodic slow mode waves that are seen as large
collective motions. We speculate that the jetlets themselves, which
are consistent with multiple interchange reconnection events near
the base of the plume, are the primary energy driver heating plasma
in the plume envelope.Solar polar (and low-latitude) plumes have been
analyzed by many authors over many years. Plumes are bright, persistent
vertical structures embedded in coronal holes over quasi-unipolar
magnetic flux concentrations. They are EUV-bright in the ~1MK lines,
slightly cooler (by ionization fraction) than the surrounding coronal
hole, persistent on short timescales of a few hours, and recurrent on
timescales of a few days. Their onset has been associated with large
X-ray jets, although not all plumes are formed that way. Plumes appear
to comprise myriad small "threads" or "strands", and may (or may not)
contribute significantly to the solar wind, though they have been
associated with myriad small, frequent eruptive ejection events.Our
results are new and interesting because they are the lowest-noise,
time-resolved observations of polar plumes to date; and they reveal
the deep association between small-scale magnetic activity and the
formation of the plumes themselves.

---------------------------------------------------------
Title: Constraints on Nonuniform Expansion in Coronal Loops
Authors: Kucera, Therese A.; DeForest, Craig; Klimchuk, James A.;
Young, Peter R.
2017SPD....4810608K Altcode:
We use measurements of coronal loop properties to constrain the
hypothesis that coronal loops expand differently in different
directions. A long standing problem in understanding coronal loops is
that although the magnetic field is expected to expand with altitude
and does indeed seem to do so on scales of active regions, individual
loops seem to have fairly uniform diameters along the length of the
loop. Malanushenko &amp; Schrijver (2013) have suggested that loops
may be expanding, but with a non-circular cross section. In this
scenario a loop might have a constant width in the plane of the sky,
but expand along the line of sight. Furthermore, such loops might be
easier to see from the point of view that does not show expansion. We
use Hinode/EIS and SDO/AIA data to measure loop intensities, electron
densities, temperatures and dimensions in order to determine the extent
to which loops may be expanding along the line of sight.

---------------------------------------------------------
Title: Fluxon Global Predictions for the 2017 Eclipse
Authors: DeForest, Craig; Lamb, Derek
2017SPD....4810702D Altcode:
We present predicted coronal morphologies for the 2017 total
solar eclipse, produced using quasi-stationary MHD simulation on a
semi-Lagrangian grid with the FLUX code. FLUX uses the "fluxon" approach
to ideal MHD: the magnetic field is modeled as a finite-element skeleton
of field lines, which experience the familiar magnetic energy density
("pressure") and curvature ("tension") forces. Ongoing and recent work
with FLUX enables simulation of solar wind flow and coronal density in
the low-beta regime, and permits global 3-D solutions without the use
of a supercomputer.Using magnetograms acquired up to one solar rotation
before the eclipse, we expect to publish fluxon-derived models 2-3
weeks before the eclipse, and will present those models side-by-side
with actual eclipse images to compare the model and actual coronae.

---------------------------------------------------------
Title: The CubeSat Imaging X-ray Solar Spectrometer (CubIXSS)
Mission Concept
Authors: Caspi, Amir; Shih, Albert Y.; Warren, Harry; DeForest,
Craig; Laurent, Glenn Thomas; Schwartz, Richard A.; Woods, Thomas
N.; Mason, James; Palo, Scott; Steslicki, Marek; Sylwester, Janusz;
Gburek, Szymon; Mrozek, Tomasz; Kowalinski, Miroslaw; Torre, Gabriele;
Crowley, Geoffrey; Schattenburg, Mark
2017SPD....4830503C Altcode:
Solar soft X-ray (SXR) observations provide important diagnostics of
plasma heating, during solar flares and quiescent times. Spectrally-
and temporally-resolved measurements are crucial for understanding
the dynamics, origins, and evolution of these energetic processes,
providing probes both into the temperature distributions and elemental
compositions of hot plasmas; spatially-resolved measurements are
critical for understanding energy transport and mass flow. A better
understanding of the thermal plasma improves our understanding of the
relationships between particle acceleration, plasma heating, and the
underlying release of magnetic energy during reconnection. We introduce
a new proposed small satellite mission, the CubeSat Imaging X-ray Solar
Spectrometer (CubIXSS), to measure spectrally- and spatially-resolved
SXRs from the quiescent and flaring Sun from a 6U CubeSat platform in
low-Earth orbit during a nominal 1-year mission. CubIXSS includes the
Amptek X123-FastSDD silicon drift detector, a low-noise, commercial
off-the-shelf (COTS) instrument enabling solar SXR spectroscopy from
~0.5 to ~30 keV with ~0.15 keV FWHM spectral resolution with low
power, mass, and volume requirements. Multiple detectors and tailored
apertures provide sensitivity to a wide range of solar conditions,
optimized for a launch during solar minimum. The precise spectra
from these instruments will provide detailed measurements of the
coronal temperature distribution and elemental abundances from the
quiet Sun to active regions and flares. CubIXSS also includes a
novel spectro-spatial imager -- the first ever solar imager on a
CubeSat -- utilizing a custom pinhole camera and Chandra-heritage
X-ray transmission diffraction grating to provide spatially- resolved,
full-Sun imaging spectroscopy from ~0.1 to ~10 keV, with ~25 arcsec and
~0.1 Å FWHM spatial and spectral resolutions, respectively. MOXSI’s
unique capabilities enable SXR spectroscopy and temperature diagnostics
of individual active regions and flares. Through its groundbreaking
new measurements, CubIXSS will improve our physical understanding of
thermal plasma processes and impulsive energy release in the solar
corona, from quiet Sun to solar flares.

---------------------------------------------------------
Title: Noise-gating to Clean Astrophysical Image Data
Authors: DeForest, C. E.
2017ApJ...838..155D Altcode: 2017arXiv170306228D
I present a family of algorithms to reduce noise in astrophysical images
and image sequences, preserving more information from the original
data than is retained by conventional techniques. The family uses
locally adaptive filters (“noise gates”) in the Fourier domain to
separate coherent image structure from background noise based on the
statistics of local neighborhoods in the image. Processing of solar
data limited by simple shot noise or by additive noise reveals image
structure not easily visible in the originals, preserves photometry
of observable features, and reduces shot noise by a factor of 10 or
more with little to no apparent loss of resolution. This reveals faint
features that were either not directly discernible or not sufficiently
strongly detected for quantitative analysis. The method works best on
image sequences containing related subjects, for example movies of solar
evolution, but is also applicable to single images provided that there
are enough pixels. The adaptive filter uses the statistical properties
of noise and of local neighborhoods in the data to discriminate between
coherent features and incoherent noise without reference to the specific
shape or evolution of those features. The technique can potentially
be modified in a straightforward way to exploit additional a priori
knowledge about the functional form of the noise.

---------------------------------------------------------
Title: Challenging Some Contemporary Views of Coronal Mass
Ejections. II. The Case for Absent Filaments
Authors: Howard, T. A.; DeForest, C. E.; Schneck, U. G.; Alden, C. R.
2017ApJ...834...86H Altcode:
When a coronal mass ejection (CME) appears in a coronagraph it often
exhibits three parts. This “classic” three-part configuration
consists of a bright leading edge, a dark circular- or teardrop-shaped
cavity, and a bright core within the cavity. It is generally
accepted that these are manifestations of coronal plasma pileup,
the driving magnetic flux rope, and the associated eruptive filament,
respectively. The latter has become accepted by the community since
coronagraph CMEs have been commonly associated with eruptive filaments
for over 40 years. In this second part of our series challenging views
on CMEs, we present the case that the inner core of the three-part
coronagraph CME may not be, and in the most common cases is not, a
filament. We present our case in the form of four exhibits showing
that most of the CMEs in a broad survey are not associated with an
eruptive filament at the Sun, and that the cores of those CMEs that
are filament-associated do not geometrically resemble or consist of
material from the associated filament. We conclude with a discussion
on the possible causes of the bright CME core and what happens to
the filament material postlaunch. We discuss how the CME core could
arise spontaneously from the eruption of a flux rope from the Sun,
or could be the result of a mathematical caustic produced by the
geometric projection of a twisted flux rope.

---------------------------------------------------------
Title: Imaging the Breakup of Coronal Structure and the Onset of
Turbulence in the Solar Wind
Authors: DeForest, C. E.
2016AGUFMSH44A..05D Altcode:
The slow solar wind is dominated by gusty, variable structure that
has been associated by many authors with turbulence. The slow wind is
thought to arise from the vicinity of the coronal streamer belt, which
is dominated by quasi-stationary, highly anisotropic, radially aligned
density structure shaped by the solar magnetic field. Photometric
analysis of the top of the streamers, in the range of apparent distances
between roughly 4° and 24° from the Sun, reveals the ultimate fate
of the streamers. In the range above 10° from the Sun, where the
transition from low-plasma-beta to high-plasma-beta is thought to occur,
we have imaged the fading and breakup of quiescent coronal streamers,
pseudostreamers, and/or rays (together, "Striae"), and the textural
transition at large scales from smooth background flow with sporadic
ejecta, to turbulent and variable flow. The result constrains and
illuminates turbulent theories of solar wind evolution, and highlights
the need for better imaging measurements in this critical transition
zone between corona and solar wind - the final unexplored frontier of
the heliosphere.

---------------------------------------------------------
Title: Development of a Homogenous Database of Bipolar Active Regions
Spanning Four Cycles
Authors: Munoz-Jaramillo, A.; Werginz, Z. A.; Vargas-Acosta, J. P.;
DeLuca, M. D.; Vargas-Dominguez, S.; Lamb, D. A.; DeForest, C. E.;
Longcope, D. W.; Martens, P.
2016AGUFMSH11A2219M Altcode:
The solar cycle can be understood as a process that alternates the
large-scale magnetic field of the Sun between poloidal and toroidal
configurations. Although the process that transitions the solar cycle
between toroidal and poloidal phases is still not fully understood,
theoretical studies, and observational evidence, suggest that this
process is driven by the emergence and decay of bipolar magnetic
regions (BMRs) at the photosphere. Furthermore, the emergence of
BMRs at the photosphere is the main driver behind solar variability
and solar activity in general; making the study of their properties
doubly important for heliospheric physics. However, in spite of their
critical role, there is still no unified catalog of BMRs spanning
multiple instruments and covering the entire period of systematic
measurement of the solar magnetic field (i.e. 1975 to present).In
this presentation we discuss an ongoing project to address this
deficiency by applying our Bipolar Active Region Detection (BARD)
code on full disk magnetograms measured by the 512 (1975-1993) and
SPMG (1992-2003) instruments at the Kitt Peak Vacuum Telescope (KPVT),
SOHO/MDI (1996-2011) and SDO/HMI (2010-present). First we will discuss
the results of our revitalization of 512 and SPMG KPVT data, then
we will discuss how our BARD code operates, and finally report the
results of our cross-callibration across instruments.The corrected
and improved KPVT magnetograms will be made available through the
National Solar Observatory (NSO) and Virtual Solar Observatory (VSO),
including updated synoptic maps produced by running the corrected KPVT
magnetograms though the SOLIS pipeline. The homogeneous active region
database will be made public by the end of 2017 once it has reached
a satisfactory level of quality and maturity. The Figure shows all
bipolar active regions present in our database (as of Aug 2016) colored
according to the instrument where they were detected. The image also
includes the names of the NSF-REU students in charge of the supervision
of the detection algorithm and the year in which they worked on the
catalog. Marker size is indicative of the total active region flux.

---------------------------------------------------------
Title: Imaging the Top of the Solar Corona and the Young Solar Wind
Authors: DeForest, C. E.; Matthaeus, W. H.; Viall, N. M.; Cranmer,
S. R.
2016AGUFMSH53A..05D Altcode:
We present the first direct visual evidence of the quasi-stationary
breakup of solar coronal structure and the rise of turbulence in
the young solar wind, directly in the future flight path of Solar
Probe. Although the corona and, more recently, the solar wind have both
been observed directly with Thomson scattered light, the transition from
the corona to the solar wind has remained a mystery. The corona itself
is highly structured by the magnetic field and the outflowing solar
wind, giving rise to radial "striae" - which comprise the familiar
streamers, pseudostreamers, and rays. These striae are not visible
in wide-field heliospheric images, nor are they clearly delineated
with in-situ measurements of the solar wind. Using careful photometric
analysis of the images from STEREO/HI-1, we have, for the first time,
directly observed the breakup of radial coronal structure and the rise
of nearly-isotropic turbulent structure in the outflowing slow solar
wind plasma between 10° (40 Rs) and 20° (80 Rs) from the Sun. These
observations are important not only for their direct science value,
but for predicting and understanding the conditions expected near SPP as
it flies through - and beyond - this final frontier of the heliosphere,
the outer limits of the solar corona.

---------------------------------------------------------
Title: Opportunities for Suborbital Space and Atmospheric Research
Facilities on Blue Origin's New Shepard Crew Capsule
Authors: Wagner, E.; DeForest, C. E.
2016AGUFM.P53C2216W Altcode:
With the emergence of the commercial space industry, researchers now
have more options than ever for conducting research aboard space-going
platforms. Blue Origin's New Shepard spacecraft offers a large-format
crew capsule, capable of carrying a wide range of high-altitude and
microgravity payloads above the Karman Line (100 km). With high flight
rates and short approval timelines, investigators are able to use data
from one flight to refine research objectives and quickly fly again,
closing the loop on the scientific method and rapidly advancing
technology development. Young investigators have ready access to
real-world experiences in building flight hardware, and more involved
missions are using this low-barrier environment to raise Technology
Readiness Level of components or subsystems. This talk will introduce
the standard interfaces and operations for payloads already flying
within the New Shepard capsule. We will also explore opportunities
for custom facilities that would allow researchers access to the
space environment at altitudes between 60 and 100 km. We will discuss
the unique science that can be conducted in this region, above where
balloons can dwell, but below satellite orbits, including investigations
in heliophysics, planetary science, and aeronomy.

---------------------------------------------------------
Title: The Future of Space Weather Forecasting with Polarized
Wide-Field Imaging
Authors: DeForest, C. E.; Howard, T. A.
2016AGUFMSH11C2254D Altcode:
Heliospheric imaging has come of age. From the original concept of
white light photometry with the Helios spacecraft through to the
HIs on board STEREO and current research on the outer limits of the
corona, heliospheric imagers have enabled important developments in
our understanding of the solar wind and transients within. Future
instruments have the potential to revolutionize space weather
forecasting. We present a summary of recent progress as it relates to
space weather prediction and new directions that a future instrument,
which would build on lessons from Coriolis/SMEI and STEREO/HI, can
take. Applications include both direct, far more precise 3-D tracking
of coronal mass ejections (CMEs) across the inner solar system;
measurement of CMEs' internal structures and their evolution; and a
more complete, up-to-date understanding ("nowcasting") of prevailing
conditions in the outer corona and solar wind. We will review of the
status quo of heliospheric imaging and the latest developments in
feature detection and measurement. We also explore the benefits of
polarized heliospheric imaging, which we believe to be the best next
step to advance heliospheric imaging and continue the scientific and
operational development of this field.

---------------------------------------------------------
Title: The best of both worlds: Using automatic detection and limited
human supervision to create a homogenous magnetic catalog spanning
four solar cycles
Authors: Muñoz-Jaramillo, Andres; Werginz, Zachary; Vargas-Acosta,
Juan Pablo; DeLuca, Michael; Windmueller, J. C.; Zhang, Jie; Longcope,
Dana; Lamb, Derek; DeForest, Craig; Vargas-Domínguez, Santiago;
Harvey, Jack; Martens, Piet
2016bida.conf.3194M Altcode: 2022arXiv220311908M
Bipolar magnetic regions (BMRs) are the cornerstone of solar
variability. They are tracers of the large-scale magnetic processes
that give rise to the solar cycle, shapers of the solar corona,
building blocks of the large-scale solar magnetic field, and significant
contributors to the free-energetic budget that gives rise to flares and
coronal mass ejections. Surprisingly, no homogeneous catalog of BMRs
exists today, in spite of the existence of systematic measurements of
the magnetic field since the early 1970's. The purpose of this work is
to address this deficiency by creating a homogenous catalog of BMRs
from the 1970's until the present. For this purpose, in this paper
we discuss the strengths and weaknesses of the automatic and manual
detection of BMRs and how both methods can be combined to form the basis
of our Bipolar Active Region Detection (BARD) code and its supporting
human supervision module. At present, the BARD catalog contains more
than 10,000 unique BMRs tracked and characterized during every day
of their observation. Here we also discuss our future plans for the
creation of an extended multi-scale magnetic catalog combining the
SWAMIS and BARD catalogs.

---------------------------------------------------------
Title: Long-term Trends in the Solar Wind Proton Measurements
Authors: Elliott, Heather A.; McComas, David J.; DeForest, Craig E.
2016ApJ...832...66E Altcode: 2016arXiv161006063E
We examine the long-term time evolution (1965-2015) of the relationships
between solar wind proton temperature (T p) and speed
(V p) and between the proton density (n p) and
speed using OMNI solar wind observations taken near Earth. We find a
long-term decrease in the proton temperature-speed (T p-V
p) slope that lasted from 1972 to 2010, but has been
trending upward since 2010. Since the solar wind proton density-speed
(n p-V p) relationship is not linear like the
T p-V p relationship, we perform power-law
fits for n p-V p. The exponent (steepness
in the n p-V p relationship) is correlated
with the solar cycle. This exponent has a stronger correlation
with current sheet tilt angle than with sunspot number because the
sunspot number maxima vary considerably from cycle to cycle and the
tilt angle maxima do not. To understand this finding, we examined
the average n p for different speed ranges, and found
that for the slow wind n p is highly correlated with the
sunspot number, with a lag of approximately four years. The fast wind
n p variation was less, but in phase with the cycle. This
phase difference may contribute to the n p-V p
exponent correlation with the solar cycle. These long-term trends are
important since empirical formulas based on fits to T p
and V p data are commonly used to identify interplanetary
coronal mass ejections, but these formulas do not include any time
dependence. Changes in the solar wind density over a solar cycle will
create corresponding changes in the near-Earth space environment and
the overall extent of the heliosphere.

---------------------------------------------------------
Title: Fading Coronal Structure and the Onset of Turbulence in the
Young Solar Wind
Authors: DeForest, C. E.; Matthaeus, W. H.; Viall, N. M.; Cranmer,
S. R.
2016ApJ...828...66D Altcode: 2016arXiv160607718D
Above the top of the solar corona, the young, slow solar wind
transitions from low-β, magnetically structured flow dominated
by radial structures to high-β, less structured flow dominated by
hydrodynamics. This transition, long inferred via theory, is readily
apparent in the sky region close to 10° from the Sun in processed,
background-subtracted solar wind images. We present image sequences
collected by the inner Heliospheric Imager instrument on board the
Solar-Terrestrial Relations Observatory (STEREO/HI1) in 2008 December,
covering apparent distances from approximately 4° to 24° from the
center of the Sun and spanning this transition in the large-scale
morphology of the wind. We describe the observation and novel techniques
to extract evolving image structure from the images, and we use those
data and techniques to present and quantify the clear textural shift in
the apparent structure of the corona and solar wind in this altitude
range. We demonstrate that the change in apparent texture is due both
to anomalous fading of the radial striae that characterize the corona
and to anomalous relative brightening of locally dense puffs of solar
wind that we term “flocculae.” We show that these phenomena are
inconsistent with smooth radial flow, but consistent with the onset
of hydrodynamic or magnetohydrodynamic instabilities leading to a
turbulent cascade in the young solar wind.

---------------------------------------------------------
Title: A small mission concept to the Sun-Earth Lagrangian L5 point
for innovative solar, heliospheric and space weather science
Authors: Lavraud, B.; Liu, Y.; Segura, K.; He, J.; Qin, G.; Temmer,
M.; Vial, J. -C.; Xiong, M.; Davies, J. A.; Rouillard, A. P.; Pinto,
R.; Auchère, F.; Harrison, R. A.; Eyles, C.; Gan, W.; Lamy, P.;
Xia, L.; Eastwood, J. P.; Kong, L.; Wang, J.; Wimmer-Schweingruber,
R. F.; Zhang, S.; Zong, Q.; Soucek, J.; An, J.; Prech, L.; Zhang,
A.; Rochus, P.; Bothmer, V.; Janvier, M.; Maksimovic, M.; Escoubet,
C. P.; Kilpua, E. K. J.; Tappin, J.; Vainio, R.; Poedts, S.; Dunlop,
M. W.; Savani, N.; Gopalswamy, N.; Bale, S. D.; Li, G.; Howard, T.;
DeForest, C.; Webb, D.; Lugaz, N.; Fuselier, S. A.; Dalmasse, K.;
Tallineau, J.; Vranken, D.; Fernández, J. G.
2016JASTP.146..171L Altcode:
We present a concept for a small mission to the Sun-Earth Lagrangian L5
point for innovative solar, heliospheric and space weather science. The
proposed INvestigation of Solar-Terrestrial Activity aNd Transients
(INSTANT) mission is designed to identify how solar coronal magnetic
fields drive eruptions, mass transport and particle acceleration that
impact the Earth and the heliosphere. INSTANT is the first mission
designed to (1) obtain measurements of coronal magnetic fields from
space and (2) determine coronal mass ejection (CME) kinematics with
unparalleled accuracy. Thanks to innovative instrumentation at a vantage
point that provides the most suitable perspective view of the Sun-Earth
system, INSTANT would uniquely track the whole chain of fundamental
processes driving space weather at Earth. We present the science
requirements, payload and mission profile that fulfill ambitious science
objectives within small mission programmatic boundary conditions.

---------------------------------------------------------
Title: The SPICE Spectral Imager on Solar Orbiter: Linking the Sun
to the Heliosphere
Authors: Fludra, Andrzej; Haberreiter, Margit; Peter, Hardi; Vial,
Jean-Claude; Harrison, Richard; Parenti, Susanna; Innes, Davina;
Schmutz, Werner; Buchlin, Eric; Chamberlin, Phillip; Thompson,
William; Gabriel, Alan; Morris, Nigel; Caldwell, Martin; Auchere,
Frederic; Curdt, Werner; Teriaca, Luca; Hassler, Donald M.; DeForest,
Craig; Hansteen, Viggo; Carlsson, Mats; Philippon, Anne; Janvier, Miho;
Wimmer-Schweingruber, Robert; Griffin, Douglas; Davila, Joseph; Giunta,
Alessandra; Waltham, Nick; Eccleston, Paul; Gottwald, Alexander;
Klein, Roman; Hanley, John; Walls, Buddy; Howe, Chris; Schuehle, Udo
2016cosp...41E.607F Altcode:
The SPICE (Spectral Imaging of the Coronal Environment) instrument is
one of the key remote sensing instruments onboard the upcoming Solar
Orbiter Mission. SPICE has been designed to contribute to the science
goals of the mission by investigating the source regions of outflows
and ejection processes which link the solar surface and corona to the
heliosphere. In particular, SPICE will provide quantitative information
on the physical state and composition of the solar atmosphere
plasma. For example, SPICE will access relative abundances of ions to
study the origin and the spatial/temporal variations of the 'First
Ionization Potential effect', which are key signatures to trace the
solar wind and plasma ejections paths within the heliosphere. Here we
will present the instrument and its performance capability to attain the
scientific requirements. We will also discuss how different observation
modes can be chosen to obtain the best science results during the
different orbits of the mission. To maximize the scientific return of
the instrument, the SPICE team is working to optimize the instrument
operations, and to facilitate the data access and their exploitation.

---------------------------------------------------------
Title: Inward Motions in the Outer Solar Corona between 7 and 12 R
⊙: Evidence for Waves or Magnetic Reconnection Jets?
Authors: Tenerani, Anna; Velli, Marco; DeForest, Craig
2016ApJ...825L...3T Altcode:
DeForest et al. used synoptic visible-light image sequences from the
COR2 coronagraph on board the STEREO-A spacecraft to identify inbound
wave motions in the outer corona beyond 7 solar radii and inferred, from
the observation, that the Alfvén surface separating the magnetically
dominated corona from the flow dominated wind must be located beyond at
least 12 solar radii from the Sun over polar coronal holes and beyond
15 solar radii in the streamer belt. Here, we attempt identification of
the observed inward signal by theoretically reconstructing height-speed
diagrams and comparing them to the observed profiles. Interpretation
in terms of Alfvén waves or Alfvénic turbulence appears to be
ruled out by the fact that the observed signal shows a deceleration
of inward motion when approaching the Sun. Fast magnetoacoustic waves
are not directly ruled out in this way, as it is possible for inward
waves observed in quadrature, but not propagating exactly radially,
to suffer total reflection as the Alfvén speed rises close to the
Sun. However, the reconstructed signal in the height-speed diagram has
the wrong concavity. A final possibility is decelerating reconnection
jets, most probably from component reconnection, in the accelerating
wind: the profile in this case appears to match the observations very
well. This interpretation does not alter the conclusion that the Alfvén
surface must be at least 12 solar radii from the photosphere. Further
observations should help constrain this process, never identified
previously in this way, in the distance range from 7 to 12 solar radii.

---------------------------------------------------------
Title: Solar abundances with the SPICE spectral imager on Solar
Orbiter
Authors: Giunta, Alessandra; Haberreiter, Margit; Peter, Hardi;
Vial, Jean-Claude; Harrison, Richard; Parenti, Susanna; Innes, Davina;
Schmutz, Werner; Buchlin, Eric; Chamberlin, Phillip; Thompson, William;
Bocchialini, Karine; Gabriel, Alan; Morris, Nigel; Caldwell, Martin;
Auchere, Frederic; Curdt, Werner; Teriaca, Luca; Hassler, Donald M.;
DeForest, Craig; Hansteen, Viggo; Carlsson, Mats; Philippon, Anne;
Janvier, Miho; Wimmer-Schweingruber, Robert; Griffin, Douglas; Baudin,
Frederic; Davila, Joseph; Fludra, Andrzej; Waltham, Nick; Eccleston,
Paul; Gottwald, Alexander; Klein, Roman; Hanley, John; Walls, Buddy;
Howe, Chris; Schuehle, Udo; Gyo, Manfred; Pfiffner, Dany
2016cosp...41E.681G Altcode:
Elemental composition of the solar atmosphere and in particular
abundance bias of low and high First Ionization Potential (FIP)
elements are a key tracer of the source regions of the solar wind. These
abundances and their spatio-temporal variations, as well as the other
plasma parameters , will be derived by the SPICE (Spectral Imaging
of the Coronal Environment) EUV spectral imager on the upcoming
Solar Orbiter mission. SPICE is designed to provide spectroheliograms
(spectral images) using a core set of emission lines arising from ions
of both low-FIP and high-FIP elements. These lines are formed over
a wide range of temperatures, enabling the analysis of the different
layers of the solar atmosphere. SPICE will use these spectroheliograms
to produce dynamic composition maps of the solar atmosphere to be
compared to in-situ measurements of the solar wind composition of
the same elements (i.e. O, Ne, Mg, Fe). This will provide a tool to
study the connectivity between the spacecraft (the Heliosphere) and
the Sun. We will discuss the SPICE capabilities for such composition
measurements.

---------------------------------------------------------
Title: An Emerging Magnetic Flux Catalog for SOHO/MDI
Authors: Lamb, Derek; Munoz-Jaramillo, Andres; DeForest, Craig
2016SPD....4730701L Altcode:
We present a catalog of emerging magnetic flux events covering
the entirety of the 15-year-long SOHO/MDI 96-minute magnetogram
dataset. Such a catalog has myriad uses in studies of the solar
dynamo and solar cycle. Our catalog is designed to mimic as nearly
as possible the Emerging Flux region catalog produced for SDO/HMI,
allowing continuity across missions and solar cycles. We will present
details of the algorithm for identifying emerging flux events, special
considerations for MDI as opposed to HMI, detailed examples of some
detected emerging flux regions, and a brief overview of statistics
of the entire catalog. The catalog will be available for querying
through the Heliophysics Event Knowledgebase, as well as for direct
downloading from Southwest Research Institute. This work has been
supported by NASA Grant NNX14AJ67G through the Heliophysics Data
Environment Enhancements program.

---------------------------------------------------------
Title: Imaging the Transition from Corona to Solar Wind
Authors: DeForest, Craig; Howard, Tim A.; Howard, Russell A.;
Tenerani, Anna
2016SPD....4710205D Altcode:
The region around the Alfvén surface -- the last frontier of the solar
system -- is largely unexplored, mostly because of the difficulty of
detecting the surface itself. Many important transitions happen between
the mid-to-outer corona and the innermost heliosphere, including:
the transition to superAlfvénic flow; the transition from structured,
highly anisotropic structure to nearly isotropic turbulent structures;
and the formation of identifiable, separable fast and slow wind
streams. We will report new results from two recent imaging campaigns
-- one with STEREO and one with SOHO/LASCO (coincidentally performed on
the 20th anniversary of the first SOHO campaign) -- to explore and image
the transition to turbulent flow and the outer boundary of the corona.

---------------------------------------------------------
Title: Inward Motions in the Outer Solar Corona Between 6 And 12 R :
Evidence For Waves or Magnetic Reconnection Jets?
Authors: Velli, Marco; Tenerani, Anna; DeForest, Craig
2016SPD....4740205V Altcode:
DeForest et al. (2014) used synoptic visible-light image sequences
from the COR2 coronagraph on board the STEREO-A spacecraft to identify
inbound wave motions in the outer corona beyond 6 solar radii and
inferred, from the observation, that the Alfven surface separating
the magnetically dominated corona from the ow dominated wind must be
located at least 12 solar radii from the Sun over polar coronal holes
and 15 solar radii in the streamer belt. Here we will discuss both
this and previous observations of inflows further down and attempt
identification of the observed inward signals. We will theoretically
reconstruct height-speed diagrams and compare them to the observed
profiles. Interpretation in terms of Alfven / magnetoacouatic modes
or Alfvenic turbulence appears to be ruled out by the fact that the
observed signal shows a deceleration of inward motion when approaching
the Sun. Fast magnetoacoustic waves are not directly ruled out in
this way, as it is possible for inward waves observed in quadrature,
but not propagating exactly radially, to suffer total reflection as
the Alfven speed rises close to the Sun. However, the reconstructed
signal in the height speed diagram has the wrong concavity. A final
possibility is decelerating reconnection jets, most probably from
component reconnection, in the accelerating wind: the profile in this
case appears to match the observations very well. This interpretation
does not alter the conclusion that the Alfven surface must be at least
12 solar radii from the photosphere.

---------------------------------------------------------
Title: First flight of SMASH, the SwRI Miniature Assembly for Solar
Hard X-rays
Authors: Caspi, Amir; Laurent, Glenn Thomas; Shoffner, Michael;
Higuera Caubilla, David; Meurisse, Jeremie; Smith, Kelly; Shih,
Albert Y.; Saint-Hilaire, Pascal; DeForest, Craig; Mansour, Nagi N.;
Hathaway, David H.
2016SPD....4720601C Altcode:
The SwRI Miniature Assembly for Solar Hard X-rays (SMASH) was
successfully flown from Antarctica in January (19-30) 2016, as
a piggy-back instrument on the Gamma-Ray Imager/Polarimeter for
Solar flares (GRIPS) high altitude balloon payload. SMASH is a
technological demonstration of a new miniaturized hard X-ray (HXR)
detector for use on CubeSats and other small spacecraft, including
the proposed CubeSat Imaging X-ray Solar Spectrometer (CubIXSS).HXRs
are the observational signatures of energetic processes on the Sun,
including plasma heating and particle acceleration. One of the goals of
CubIXSS will be to address the question of how plasma is heated during
solar flares, including the relationship between thermal plasma and
non-thermal particles. SMASH demonstrated the space-borne application
of the commercial off-the-shelf Amptek X123-CdTe, a miniature cadmium
telluride photon-counting HXR spectrometer. The CdTe detector has a
physical area of 25 mm^2 and 1 mm fully-depleted thickness, with a ~100
micron Be window; with on-board thermoelectric cooling and pulse pile-up
rejection, it is sensitive to solar photons from ~5 to ~100 keV with
~0.5-1.0 keV FWHM resolution. Photons are accumulated into histogram
spectra with customizable energy binning and integration time. With
modest resource requirements (~1/8 U, ~200 g, ~2.5 W) and low cost
(~$10K), the X123-CdTe is an attractive solution for HXR measurements
from budget- and resource-limited platforms such as CubeSats. SMASH
flew two identical X123-CdTe detectors for redundancy and increased
collecting area; the supporting electronics (power, CPU) were largely
build-to-print using the Miniature X-ray Solar Spectrometer (MinXSS)
CubeSat design.We review the SMASH mission, design, and detector
performance during the 12-day Antarctic flight. We present current
progress on our data analysis of observed solar flares, and discuss
future applications of the space-qualified X123-CdTe detector, including
the CubIXSS mission concept that incorporates two such detectors.

---------------------------------------------------------
Title: B-SSIPP: A Miniature Solar Observatory for Rocket or Balloon
Flight
Authors: DeForest, Craig; Laurent, Glenn Thomas; Diller, Jed;
Brownsberger, Judy
2016SPD....47.0803D Altcode:
The Southwest Solar Instrument Pointing Package (SSIPP) is a miniature
solar observatory for flight application. Conceived as a way to lower
barriers to entry to spaceflight, SSIPP conditions a broadband solar
beam for use by an IR, visible, or UV instrument on an optical table
-- just as do ground-based observatories. The beam is conditioned by
a closed-loop tip/tilt pointing system that can lock onto the Sun
over a 20° cone of angles, and maintain arcsecond-class pointing
from a dynamic flight platform. SSIPP was originally conceived as an
instrument platform for the XCOR Lynx suborbital sportsrocket. It has
been adapted for ballloon flight, incorporating a novel coarse pointing
system that measures torsional pendulation in-flight to construct a
stable pointing law on-the-fly. First flight is projected for June
2016 (shortly after SPD). We present status, major design elements,
and future plans for the platform.

---------------------------------------------------------
Title: Comparing Loop Cross Sections Observed with Hi-C and AIA/SDO
Authors: Klimchuk, James A.; DeForest, Craig
2016SPD....47.0301K Altcode:
Many studies have reported coronal loop widths measured with AIA/SDO,
TRACE, and other data. For warm loops (T ~ 1 MK), the characteristic
diameter is about 1500 km. Sub-structure is likely to exist on smaller
scales, but the envelope of the "strands" has this typical size. Since
1500 km (2 arcsec) is not large compared to the spatial resolution of
the observations, there remained a question about whether the loops
are actually much thinner. To address this concern, we have measured
the widths of several loops observed at 193 A by both AIA and the Hi-C
rocket experiment. Hi-C has 3-6 times better spatial resolution, so if
the loops are substantially unresolved by AIA, it should be readily
apparent. We find that the measured widths are very similar. Small
differences (&lt; 25%) are explainable by uncertainties in the point
spread functions. We conclude that previous measurements of loop
widths made by AIA and TRACE are essentially correct. We also find
little evidence for loop sub-structure at the resolution of Hi-C. The
individual strands that comprise loops are therefore smaller than 200
km. These results have important implications for coronal heating.

---------------------------------------------------------
Title: The Rapid Acquisition Imaging Spectrograph Experiment (RAISE)
Sounding Rocket Investigation
Authors: Laurent, Glenn T.; Hassler, Donald M.; Deforest, Craig;
Slater, David D.; Thomas, Roger J.; Ayres, Thomas; Davis, Michael; de
Pontieu, Bart; Diller, Jed; Graham, Roy; Michaelis, Harald; Schuele,
Udo; Warren, Harry
2016JAI.....540006L Altcode:
We present a summary of the solar observing Rapid Acquisition
Imaging Spectrograph Experiment (RAISE) sounding rocket program
including an overview of the design and calibration of the instrument,
flight performance, and preliminary chromospheric results from the
successful November 2014 launch of the RAISE instrument. The RAISE
sounding rocket payload is the fastest scanning-slit solar ultraviolet
imaging spectrograph flown to date. RAISE is designed to observe the
dynamics and heating of the solar chromosphere and corona on time
scales as short as 100-200ms, with arcsecond spatial resolution and
a velocity sensitivity of 1-2km/s. Two full spectral passbands over
the same one-dimensional spatial field are recorded simultaneously
with no scanning of the detectors or grating. The two different
spectral bands (first-order 1205-1251Å and 1524-1569Å) are imaged
onto two intensified Active Pixel Sensor (APS) detectors whose focal
planes are individually adjusted for optimized performance. RAISE
reads out the full field of both detectors at 5-10Hz, recording up
to 1800 complete spectra (per detector) in a single 6-min rocket
flight. This opens up a new domain of high time resolution spectral
imaging and spectroscopy. RAISE is designed to observe small-scale
multithermal dynamics in Active Region (AR) and quiet Sun loops,
identify the strength, spectrum and location of high frequency waves
in the solar atmosphere, and determine the nature of energy release
in the chromospheric network.

---------------------------------------------------------
Title: The utility of polarized heliospheric imaging for space
weather monitoring
Authors: DeForest, C. E.; Howard, T. A.; Webb, D. F.; Davies, J. A.
2016SpWea..14...32D Altcode:
A polarizing heliospheric imager is a critical next generation tool
for space weather monitoring and prediction. Heliospheric imagers can
track coronal mass ejections (CMEs) as they cross the solar system,
using sunlight scattered by electrons in the CME. This tracking has
been demonstrated to improve the forecasting of impact probability and
arrival time for Earth-directed CMEs. Polarized imaging allows locating
CMEs in three dimensions from a single vantage point. Recent advances
in heliospheric imaging have demonstrated that a polarized imager is
feasible with current component technology.Developing this technology
to a high technology readiness level is critical for space weather
relevant imaging from either a near-Earth or deep-space mission. In this
primarily technical review, we developpreliminary hardware requirements
for a space weather polarizing heliospheric imager system and outline
possible ways to flight qualify and ultimately deploy the technology
operationally on upcoming specific missions. We consider deployment
as an instrument on NOAA's Deep Space Climate Observatory follow-on
near the Sun-Earth L1 Lagrange point, as a stand-alone constellation
of smallsats in low Earth orbit, or as an instrument located at
the Sun-Earth L5 Lagrange point. The critical first step is the
demonstration of the technology, in either a science or prototype
operational mission context.

---------------------------------------------------------
Title: New Instruments for Spectrally-Resolved Solar Soft X-ray
Observations from CubeSats, and Larger Missions
Authors: Caspi, A.; Shih, A.; Warren, H. P.; DeForest, C. E.; Woods,
T. N.
2015AGUFMSH13B2444C Altcode: 2015AGUFMSH13B2444D
Solar soft X-ray (SXR) observations provide important diagnostics of
plasma heating, during solar flares and quiescent times. Spectrally-
and temporally-resolved measurements are crucial for understanding the
dynamics and evolution of these energetic processes; spatially-resolved
measurements are critical for understanding energy transport. A better
understanding of the thermal plasma informs our interpretation of
hard X-ray (HXR) observations of nonthermal particles, improving our
understanding of the relationships between particle acceleration,
plasma heating, and the underlying release of magnetic energy during
reconnection. We introduce a new proposed mission, the CubeSat
Imaging X-ray Solar Spectrometer (CubIXSS), to measure spectrally-
and spatially-resolved SXRs from the quiescent and flaring Sun from
a 6U CubeSat platform in low-Earth orbit during a nominal 1-year
mission. CubIXSS includes the Amptek X123-SDD silicon drift detector,
a low-noise, commercial off-the-shelf (COTS) instrument enabling
solar SXR spectroscopy from ~0.5 to ~30 keV with ~0.15 keV FWHM
spectral resolution with low power, mass, and volume requirements. An
X123-CdTe cadmium-telluride detector is also included for ~5-100
keV HXR spectroscopy with ~0.5-1 keV FWHM resolution. CubIXSS also
includes a novel spectro-spatial imager -- the first ever solar imager
on a CubeSat -- utilizing a pinhole aperture and X-ray transmission
diffraction grating to provide full-Sun imaging from ~0.1 to ~10 keV,
with ~25 arcsec and ~0.1 Å FWHM spatial and spectral resolutions,
respectively. We discuss scaled versions of these instruments, with
greater sensitivity and dynamic range, and significantly improved
spectral and spatial resolutions for the imager, for deployment on
larger platforms such as Small Explorer missions.

---------------------------------------------------------
Title: Synthetic White-light Imagery for the Wide-field Imager for
Solar Probe Plus (WISPR)
Authors: Liewer, P. C.; Thernisien, A. F.; Vourlidas, A.; Howard,
R.; DeForest, C. E.; DeJong, E.; Desai, A.
2015AGUFMSH31C2426L Altcode:
The Solar Probe Plus trajectory, approaching within 10 solar radii, will
enable the white light imager, WISPR, to fly through corona features
now only imaged remotely. The dependency of the Thomson scattering
on the imaging geometry (distance and angle from the Sun) dictates
that the outer WISPR telescope will be sensitive to the emission
from plasma close to the spacecraft, in contrast to the situation
for imaging from Earth orbit. Thus WISPR will be the first 'local'
imager providing a crucial link between the large-scale corona and
SPP's in-situ measurements. The high speed at perihelion will provide
tomographic-like views of coronal structures at ≤1° resolution. As
SPP approaches perihelion, WISPR, with a 95° radial by 58° transverse
field of view, will resolve the fine-scale structure with high spatial
resolution. To prepare for this unprecedented viewing of the structure
of the inner corona, we are creating synthetic white light images and
animations from the WISPR viewpoint using the white-light ray-tracing
package developed at NRL (available through SolarSoft). We will present
simulated observations of multi-strand models of coronal streamers and
flux ropes of various size and make comparisons with views from Earth,
Solar Orbiter and SPP. Analysis techniques for WISPR images will also
be discussed.

---------------------------------------------------------
Title: Contextualizing Solar Cycle 24: Report on the Development of
a Homogenous Database of Bipolar Active Regions Spanning Four Cycles
Authors: Munoz-Jaramillo, A.; Werginz, Z. A.; DeLuca, M. D.;
Vargas-Acosta, J. P.; Longcope, D. W.; Harvey, J. W.; Martens, P.;
Zhang, J.; Vargas-Dominguez, S.; DeForest, C. E.; Lamb, D. A.
2015AGUFMSH33D..06M Altcode:
The solar cycle can be understood as a process that alternates the
large-scale magnetic field of the Sun between poloidal and toroidal
configurations. Although the process that transitions the solar cycle
between toroidal and poloidal phases is still not fully understood,
theoretical studies, and observational evidence, suggest that this
process is driven by the emergence and decay of bipolar magnetic
regions (BMRs) at the photosphere. Furthermore, the emergence of
BMRs at the photosphere is the main driver behind solar variability
and solar activity in general; making the study of their properties
doubly important for heliospheric physics. However, in spite of their
critical role, there is still no unified catalog of BMRs spanning
multiple instruments and covering the entire period of systematic
measurement of the solar magnetic field (i.e. 1975 to present).In
this presentation we discuss an ongoing project to address this
deficiency by applying our Bipolar Active Region Detection (BARD)
code on full disk magnetograms measured by the 512 (1975-1993) and
SPMG (1992-2003) instruments at the Kitt Peak Vacuum Telescope (KPVT),
SOHO/MDI (1996-2011) and SDO/HMI (2010-present). First we will discuss
the results of our revitalization of 512 and SPMG KPVT data, then we
will discuss how our BARD code operates, and finally report the results
of our cross-callibration.The corrected and improved KPVT magnetograms
will be made available through the National Solar Observatory (NSO)
and Virtual Solar Observatory (VSO), including updated synoptic maps
produced by running the corrected KPVT magnetograms though the SOLIS
pipeline. The homogeneous active region database will be made public
by the end of 2017 once it has reached a satisfactory level of quality
and maturity. The Figure shows all bipolar active regions present in
our database (as of Aug 2015) colored according to the sign of their
leading polarity. Marker size is indicative of the total active region
flux. Anti-Hale regions are shown using solid markers.

---------------------------------------------------------
Title: Remote sensing of plasma motion and turbulence near the
Alfvén surface
Authors: DeForest, C. E.
2015AGUFMSH44A..01D Altcode:
Despite a rich nearly-century-long history, Thomson scattering has not
been fully exploited as a remote-sensing tool in the corona and nascent
solar wind. In particular, stable deep-space coronagraphs such as
SOHO/LASCO and STEREO/SECCHI enable time-dependent, photometric analyses
that transcend basic feature tracking and brightness estimation. These
techniques offer direct insight into the plasma conditions in the outer
corona. In particular, fluctuations in the outer coronal brightness
comprise both the familiar inhomogeneous "blobs" of material first
tracked quantitatively with SOHO/LASCO, and also a recently-discovered
compressive wave field that permits remote probing of the plasma even
though individual wave fronts do not stand out visually. I will discuss
recent and current measurements of this wave field in the outer corona
as a means to probe outer coronal heating and wind acceleration near the
transition from corona to heliosphere (known as the Alfvén surface);
and present current results from a study of the transition from mostly
smooth to mostly turbulent flow in the nascent solar wind.

---------------------------------------------------------
Title: 2-D and 3-D Heliospheric Imaging from LEO, L1 and L5:
Instruments, Vantage Points, and Applications
Authors: DeForest, C. E.
2015AGUFMSH14A..03D Altcode:
Heliospheric imaging has come of age scientifically, and multiple
heliospheric imagers are either operating or being built to operate
on scientific missions. Much study and effort has been put into the
advantages of solar wind imaging for space weather prediction. For
example, CME tracking (either in 3-D with polarization, or in an image
plane from a vantage far from Earth) has the potential to greatly
increase arrival time predictions. Likewise, higher spatial and
temporal resolution could provide critical clues about the important
N/S component of the entrained magnetic field, by connecting signed
surface magnetograms of the Sun to particular structures observed in
the corona and, later, in the ICME. I will discuss the current state
of understanding of polarized and/or high resolution heliospheric
imaging as it relates to space weather forecasting, the relative
advantages of an instrument at LEO, L1, or L5, and desiderata to
exploit currently-validated and under-consideration techniques in
an operational, prototype, or scientific next-generation solar wind
imaging experiment.

---------------------------------------------------------
Title: Requirements for an Operational Coronagraph
Authors: Howard, R.; Vourlidas, A.; Harrison, R. A.; Bisi, M. M.;
Plunkett, S. P.; Socker, D. G.; Eyles, C. J.; Webb, D. F.; DeForest,
C. E.; Davies, J. A.; Howard, T. A.; de Koning, C. A.; Gopalswamy,
N.; Davila, J. M.; Tappin, J.; Jackson, B. V.
2015AGUFMSH14A..02H Altcode:
Coronal mass ejections (CMEs) have been shown to be the major driver
of the non-recurrent space weather events and geomagnetic storms. The
utility of continuously monitoring such events has been very effectively
demonstrated by the LASCO experiment on the SOHO mission. However SOHO
is aging, having been launched 20 years ago on Dec 2, 1995. The STEREO
mission, in which two spacecraft in orbits about the sun are drifting
away from earth, has shown the utility of multiple viewpoints off the
sun-earth line. Up to now the monitoring of CMES has been performed
by scientific instruments such as LASCO and SECCHI with capabilities
beyond those required to record the parameters that are needed to
forecast the impact at earth. However, there is great interest within
the US NOAA and the UK Met Office to launch operational coronagraphs
to L1 and L5. An ad-hoc group was formed to define the requirements
of the L5 coronagraph. In this paper we present some requirements that
must be met by operational coronagraphs. The Office of Naval Research
is gratefully acknowledged.

---------------------------------------------------------
Title: Erratum: “Feasibility of Heliospheric Imaging from Near
Earth” <A href="/abs/2015ApJ...804..126D">(2015, ApJ, 804, 126)</A>
Authors: DeForest, C. E.; Howard, T. A.
2015ApJ...813..139D Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Turbulence in the Solar Wind Measured with Comet Tail Test
Particles
Authors: DeForest, C. E.; Matthaeus, W. H.; Howard, T. A.; Rice, D. R.
2015ApJ...812..108D Altcode:
By analyzing the motions of test particles observed remotely in the
tail of Comet Encke, we demonstrate that the solar wind undergoes
turbulent processing enroute from the Sun to the Earth and that the
kinetic energy entrained in the large-scale turbulence is sufficient to
explain the well-known anomalous heating of the solar wind. Using the
heliospheric imaging (HI-1) camera on board NASA's STEREO-A spacecraft,
we have observed an ensemble of compact features in the comet tail as
they became entrained in the solar wind near 0.4 AU. We find that the
features are useful as test particles, via mean-motion analysis and
a forward model of pickup dynamics. Using population analysis of the
ensemble's relative motion, we find a regime of random-walk diffusion
in the solar wind, followed, on larger scales, by a surprising regime
of semiconfinement that we attribute to turbulent eddies in the
solar wind. The entrained kinetic energy of the turbulent motions
represents a sufficient energy reservoir to heat the solar wind to
observed temperatures at 1 AU. We determine the Lagrangian-frame
diffusion coefficient in the diffusive regime, derive upper limits
for the small scale coherence length of solar wind turbulence, compare
our results to existing Eulerian-frame measurements, and compare the
turbulent velocity with the size of the observed eddies extrapolated to
1 AU. We conclude that the slow solar wind is fully mixed by turbulence
on scales corresponding to a 1-2 hr crossing time at Earth; and that
solar wind variability on timescales shorter than 1-2 hr is therefore
dominated by turbulent processing rather than by direct solar effects.

---------------------------------------------------------
Title: Feasibility of Heliospheric Imaging from Near Earth
Authors: DeForest, C. E.; Howard, T. A.
2015ApJ...804..126D Altcode:
Imaging solar wind structures via Thomson scattered sunlight has
proved important to understanding the inner heliosphere. The principal
challenge of heliospheric imaging is background subtraction: typical
solar wind features are fainter than the zodiacal light and starfield
by 2-3 orders of magnitude. Careful post-processing is required to
separate the solar wind signal from the static background. Remnant
background, and not photon noise, is the dominant noise source in
current STEREO data. We demonstrate that 10× shorter exposure times
would not strongly affect the noise level in these data. Further,
we demonstrate that current processing techniques are sufficient to
separate not only the existing background of the STEREO images but also
diffuse variable backgrounds such as are expected to be seen from low
Earth orbit. We report on a hare-and-hounds style study, demonstrating
blind signal extraction from STEREO/HI-2 data that have been degraded
by the addition of large-scale, time-dependent artifacts to simulate
viewing through airglow or high-altitude aurora. We demonstrate
removal of these effects via image processing, with little degradation
compared to the original. Even with as few as three highly degraded
source images over 48 hr, it is possible to detect and track large
coronal mass ejections more than 40° from the Sun. This implies
that neither the high altitude aurora discovered by Coriolis/SMEI,
nor airglow effects seen from low Earth orbit, are impediments to a
hypothetical next-generation heliospheric imager in low Earth orbit;
and also that post-processing is as important to heliospheric image
qualitiy as are optical contamination effects.

---------------------------------------------------------
Title: Measuring the Turbulent Solar Wind
Authors: DeForest, Craig; Matthaeus, William; Howard, Tim
2015TESS....110806D Altcode:
The slow solar wind is turbulent, a fact that may explain the
variability of the slow wind at Earth. But the nature and strength
of the turbulence has been hard to quantify because measurements
have been limited to in-situ detection of variations in measurable
parameters. Remote imaging of comet tails offers a unique opportunity
to study the paths of localized "test particles" in the solar wind,
and to analyze the motion in the same way that hydrodynamicists might
study turbulence in water with test particles. We report on a careful
analysis of the motion of 230 individually tracked features in the tail
of a comet observed with STEREO/HI-1, which interacted strongly with
the solar wind between 0.2 and 0.3 AU during the observation period,
and draw deep conclusions about the nature of solar wind variability.

---------------------------------------------------------
Title: RAISE (Rapid Acquisition Imaging Spectrograph Experiment):
Results and Instrument Status
Authors: Laurent, Glenn T.; Hassler, Donald; DeForest, Craig; Ayres,
Tom; Davis, Michael; DePontieu, Bart; Diller, Jed; Graham, Roy;
Schule, Udo; Warren, Harry
2015TESS....140203L Altcode:
We present initial results from the successful November 2014 launch of
the RAISE (Rapid Acquisition Imaging Spectrograph Experiment) sounding
rocket program, including intensity maps, high-speed spectroheliograms
and dopplergrams, as well as an update on instrument status. The
RAISE sounding rocket payload is the fastest high-speed scanning-slit
imaging spectrograph flown to date and is designed to observe the
dynamics and heating of the solar chromosphere and corona on time
scales as short as 100-200ms, with arcsecond spatial resolution and a
velocity sensitivity of 1-2 km/s. The instrument is based on a class of
UV/EUV imaging spectrometers that use only two reflections to provide
quasi-stigmatic performance simultaneously over multiple wavelengths
and spatial fields. The design uses an off-axis parabolic telescope
mirror to form a real image of the sun on the spectrometer entrance
aperture. A slit then selects a portion of the solar image, passing its
light onto a near-normal incidence toroidal grating, which re-images
the spectrally dispersed radiation onto two array detectors. Two
full spectral passbands over the same one-dimensional spatial field
are recorded simultaneously with no scanning of the detectors or
grating. The two different spectral bands (1st-order 1205-1243Å and
1526-1564Å) are imaged onto two intensified Active Pixel Sensor (APS)
detectors whose focal planes are individually adjusted for optimized
performance. RAISE reads out the full field of both detectors at 5-10
Hz, allowing us to record over 1,500 complete spectral observations in
a single 5-minute rocket flight, opening up a new domain of high time
resolution spectral imaging and spectroscopy. RAISE is designed to
study small-scale multithermal dynamics in active region (AR) loops,
explore the strength, spectrum and location of high frequency waves
in the solar atmosphere, and investigate the nature of transient
brightenings in the chromospheric network.

---------------------------------------------------------
Title: Status of the SWAMIS Emerging Flux Detection and Feature
Tracking Codes
Authors: Lamb, Derek A.; DeForest, Craig; Davey, Alisdair R.
2015TESS....140308L Altcode:
We describe recent improvements to the SWAMIS magnetic feature
tracking code for SDO/HMI data. In particular, we detail recent
substantial improvements in the detection of emerging flux regions in
near-real-time magnetograms, show detailed examples of the detected
events, and report on the status of the code in the HMI analysis
pipeline. In addition, we describe some recent improvements in
efficiently analyzing full-resolution, full disk HMI magnetograms,
and describe our plans for future code development.

---------------------------------------------------------
Title: Spatio-temporal Patterns in Arcsecond-scale Flux Emergence
Events
Authors: Lamb, Derek A.; DeForest, Craig
2015TESS....111106L Altcode:
Active regions’ pattern of magnetic flux emergence across latitude
and time has been well described for nearly a century, and is
generally understood in the context of the solar cycle. The pattern
of emergence at smaller scales is thought to be basically random
in space and time. Case studies of certain small-scale emergence
events have suggested the possibility that some of these events
are related to others in some way: the observations typically show
simultaneous emergence events in close proximity to each other, and in
some cases also with a similarity in the geometric orientation of the
events. Whether these events are merely chance encounters, or signify
a subsurface topological connection has not been addressed. Here we
present SDO/HMI observations of some case studies of this clustered
flux emergence, as well as a catalog of flux emergence events over
a short time period, obtained through both manual and automated
methods. Finally, we present a preliminary statistical analysis of
the flux emergence events to determine whether these are simply an
effect of an acute, imaginative human visual system or significantly
unlikely to be chance encounters.

---------------------------------------------------------
Title: Chromospheric Rapid Blueshifted Excursions Observed with IBIS
and their Association with Photospheric Magnetic Field Evolution
Authors: Deng, Na; Chen, Xin; Liu, Chang; Jing, Ju; Tritschler,
Alexandra; Reardon, Kevin P.; Lamb, Derek A.; Deforest, Craig E.;
Denker, Carsten; Wang, Shuo; Liu, Rui; Wang, Haimin
2015ApJ...799..219D Altcode: 2014arXiv1412.4038D
Chromospheric rapid blueshifted excursions (RBEs) are suggested to
be the disk counterparts of type II spicules at the limb and believed
to contribute to the coronal heating process. Previous identification
of RBEs was mainly based on feature detection using Dopplergrams. In
this paper, we study RBEs on 2011 October 21 in a very quiet region at
the disk center, which were observed with the high-cadence imaging
spectroscopy of the Ca II 8542 Å line from the Interferometric
Bidimensional Spectrometer (IBIS). By using an automatic spectral
analysis algorithm, a total of 98 RBEs are identified during an 11
minute period. Most of these RBEs have either a round or elongated
shape, with an average area of 1.2 arcsec2. The detailed
temporal evolution of spectra from IBIS makes possible a quantitative
determination of the velocity (~16 km s-1) and acceleration
(~400 m s-2) of Ca II 8542 RBEs, and reveals an additional
deceleration (~-160 m s-2) phase that usually follows the
initial acceleration. In addition, we also investigate the association
of RBEs with the concomitant photospheric magnetic field evolution,
using coordinated high-resolution and high-sensitivity magnetograms
made by Hinode. Clear examples are found where RBEs appear to be
associated with the preceding magnetic flux emergence and/or the
subsequent flux cancellation. However, further analysis with the aid
of the Southwest Automatic Magnetic Identification Suite does not
yield a significant statistical association between these RBEs and
magnetic field evolution. We discuss the implications of our results
in the context of understanding the driving mechanism of RBEs.

---------------------------------------------------------
Title: Observations of a Solar Wind Domain Boundary Extending 1 AU
from the Sun
Authors: Howard, T. A.; DeForest, C. E.
2015ApJ...800L..25H Altcode:
We present measurements of a spatially coherent structure that extended
over 0.5 AU through the solar wind. This is the first observation of
such a feature in white light, and it is rare, possibly unique. While
we cannot present conclusive evidence of its origin and nature, we
speculate, based on white-light observation and measurement, that
it is a domain boundary between fast and slow solar wind streams,
possibly arising from the flank of a coronal mass ejection that
erupted some 10 hr prior to its appearance. The puzzling aspect
of this feature is that it maintained its structural integrity for
several days in the solar wind at distances near 1 AU, yet it showed
no signs of turbulent break up. This is despite an expectation, which
we derive from basic hydrodynamic theory, that turbulence induced by
the Kelvin-Helmholtz instability should at least be present there. We
present our observations, measurements, and speculations and conclude
with an appeal to the wider community for suggestions as to the source,
nature, and uniqueness of this feature.

---------------------------------------------------------
Title: Instant: An Innovative L5 Small Mission Concept for Coordinated
Science with Solar Orbiter and Solar Probe Plus
Authors: Lavraud, B.; Liu, Y. D.; Harrison, R. A.; Liu, W.;
Auchere, F.; Gan, W.; Lamy, P. L.; Xia, L.; Eastwood, J. P.;
Wimmer-Schweingruber, R. F.; Zong, Q.; Rochus, P.; Maksimovic, M.;
Temmer, M.; Escoubet, C. P.; Kilpua, E.; Rouillard, A. P.; Davies,
J. A.; Vial, J. C.; Gopalswamy, N.; Bale, S. D.; Li, G.; Howard,
T. A.; DeForest, C. E.
2014AGUFMSH21B4109L Altcode:
We will present both the science objectives and related instrumentation
of a small solar and heliospheric mission concept, INSTANT:
INvestigation of Solar-Terrestrial Activity aNd Transients. It will be
submitted as an opportunity to the upcoming ESA-China S-class mission
call later this year. This concept was conceived to allow innovative
measurements and unprecedented, early determination of key properties
of Earthbound CMEs from the L5 vantage point. Innovative measurements
will include magnetic field determination in the corona thanks to
Hanle measurement in Lyman-α and polarized heliospheric imaging
for accurate determination of CME trajectories. With complementary
in situ measurements, it will uniquely permit solar storm science,
solar storm surveillance, and synergy with Solar Orbiter and Solar
Probe Plus (the ESA-China S2 mission launch is planned in 2021).

---------------------------------------------------------
Title: Magnetic Feature Tracking in the SDO Era: Past Sacrifices,
Recent Advances, and Future Possibilities
Authors: Lamb, D. A.; DeForest, C. E.; Van Kooten, S.
2014AGUFMSH34A..01L Altcode:
When implementing computer vision codes, a common reaction to the
high angular resolution and the high cadence of SDO's image products
has been to reduce the resolution and cadence of the data so that it
"looks like" SOHO data. This can be partially justified on physical
grounds: if the phenomenon that a computer vision code is trying to
detect was characterized in low-resolution, low cadence data, then the
higher quality data may not be needed. But sacrificing at least two,
and sometimes all four main advantages of SDO's imaging data (the other
two being a higher duty cycle and additional data products) threatens
to also discard the perhaps more subtle discoveries waiting to be made:
a classic baby-with-the-bath-water situation. In this presentation,
we discuss some of the sacrifices made in implementing SWAMIS-EF, an
automatic emerging magnetic flux region detection code for SDO/HMI,
and how those sacrifices simultaneously simplified and complicated
development of the code. SWAMIS-EF is a feature-finding code, and we
will describe some situations and analyses in which a feature-finding
code excels, and some in which a different type of algorithm may produce
more favorable results. In particular, because the solar magnetic
field is irreducibly complex at the currently observed spatial scales,
searching for phenomena such as flux emergence using even semi-strict
physical criteria often leads to large numbers of false or missed
detections. This undesirable behavior can be mitigated by relaxing
the imposed physical criteria, but here too there are tradeoffs:
decreased numbers of missed detections may increase the number of
false detections if the selection criteria are not both sensitive
and specific to the searched-for phenomenon. Finally, we describe
some recent steps we have taken to overcome these obstacles, by fully
embracing the high resolution, high cadence SDO data, optimizing and
partially parallelizing our existing code as a first step to allow fast
magnetic feature tracking of full resolution HMI magnetograms. Even with
the above caveats, if used correctly such a tool can provide a wealth
of information on the positions, motions, and patterns of features,
enabling large, cross-scale analyses that can answer important questions
related to the solar dynamo and to coronal heating.

---------------------------------------------------------
Title: New Platforms for Suborbital Astronomical Observations and In
Situ Atmospheric Measurements: Spacecraft, Instruments, and Facilities
Authors: Rodway, K.; DeForest, C. E.; Diller, J.; Vilas, F.; Sollitt,
L. S.; Reyes, M. F.; Filo, A. S.; Anderson, E.
2014AGUFMSH52B..06R Altcode:
Suborbital astronomical observations have over 50 years' history
using NASA's sounding rockets and experimental space planes. The new
commercial space industry is developing suborbital reusable launch
vehicles (sRLV's) to provide low-cost, flexible, and frequent access
to space at ~100 km altitude. In the case of XCOR Aerospace's Lynx
spacecraft, the vehicle design and capabilities work well for hosting
specially designed experiments that can be flown with a human-tended
researcher or alone with the pilot on a customized mission. Some of
the first-generation instruments and facilities that will conduct
solar observations on dedicated Lynx science missions include the
SwRI Solar Instrument Pointing Platform (SSIPP) and Atsa Suborbital
Observatory, as well as KickSat sprites, which are picosatellites
for in situ atmospheric and solar phenomena measurements. The SSIPP
is a demonstration two-stage pointed solar observatory that operates
inside the Lynx cockpit. The coarse pointing stage includes the pilot
in the feedback loop, and the fine stage stabilizes the solar image
to achieve arcsecond class pointing. SSIPP is a stepping-stone to
future external instruments that can operate with larger apertures and
shorter wavelengths in the solar atmosphere. The Planetary Science
Institute's Atsa Suborbital Observatory combines the strengths of
ground-based observatories and space-based observing to create a
facility where a telescope is maintained and used interchangeably with
either in-house facility instruments or user-provided instruments. The
Atsa prototype is a proof of concept, hand-guided camera that mounts
on the interior of the Lynx cockpit to test target acquisition and
tracking for human-operated suborbital astronomy. KickSat sprites are
mass-producible, one inch printed circuit boards (PCBs) populated by
programmable off the shelf microprocessors and radios for real time
data transmission. The sprite PCBs can integrate chip-based radiometers,
magnetometers, accelerometers, etc. This low-cost, customizable platform
provides researchers the ability to design immediately responsive,
repeatable, high resolution experiments.

---------------------------------------------------------
Title: The Distribution and Behaviour of Photospheric Magnetic
Features
Authors: Parnell, C. E.; Lamb, D. A.; DeForest, C. E.
2014AGUFMSH34A..05P Altcode:
Over the past two decades enormous amounts of data on the magnetic
fields of the solar photosphere have been produced by both ground-based
(Kitt Peak &amp; SOLIS), as well as space-based instruments (MDI,
Hinode &amp; HMI). In order to study the behaviour and distribution of
photospheric magnetic features, efficient automated detection routines
need to be utilised to identify and track magnetic features. In this
talk, I will discuss the pros and cons of different automated magnetic
feature identification and tracking routines with a special focus on the
requirements of these codes to deal with the large data sets produced by
HMI. By patching together results from Hinode and MDI (high-res &amp;
full-disk), the fluxes of magnetic features were found to follow a
power-law over 5 orders of magnitude. At the strong flux tail of this
distribution, the power law was found to fall off at solar minimum,
but was maintained over all fluxes during solar maximum. However,
the point of deflection in the power-law distribution occurs at a
patching point between instruments and so questions remain over the
reasons for the deflection. The feature fluxes determined from the
superb high-resolution HMI data covers almost all of the 5 orders of
magnitude. Considering both solar mimimum and solar maximum HMI data
sets, we investigate whether the power-law over 5 orders of magnitude in
flux still holds. Furthermore, we investigate the behaviour of magnetic
features in order to probe the nature of their origin. In particular, we
analyse small-scale flux emergence events using HMI data to investigate
the existence of a small-scale dynamo just below the solar photosphere.

---------------------------------------------------------
Title: DELPHI: A Pathfinder to LCAS on board the International
Space Station
Authors: DeForest, C. E.; Howard, T. A.; Laurent, G. T.; Diller, J.
2014AGUFMSH53B4232D Altcode:
NASA's venerable LCAS sounding rocket program has been the primary
means to test new space instrumentation for space physics, for
over 60 years. Recently, new LCAS pathways have been introduced for
instruments and science that require longer exposure than a sounding
rocket affords. The International Space Station (ISS) offers similar
infrastructure to a sounding rocket, with ample mass and volume,
controlled attitude, and predefined and generous power and telemetry
interfaces. The DEmonstration LEO Polarizing Heliospheric Imager
is an LCAS mission that pioneers replacing the SPARCS+black brant
stack with the ISS itself, to exploit the environment afforded by
the ISS and demonstrate new instrumentation on-orbit. DELPHI is a
solar off-pointed heliospheric imager that demonstrates the use of
pB/B and quantitative photometry to locate solar wind features in 3-D
with high spatial resolution, in a few-month mission. It makes use
of the stable environment and high telemetry volume (1Mbps) on ISS to
improve image quality with ground postprocessing. It is built on the
ISS-standard ExPA interface and robotically deployed from the Space-X
Dragon trunk to an external mount location. We will discuss some of
the engineering and programmatic trades go with designing an orbital
sounding-rocket-class instrument, and advocate using ISS as a future
platform for instrument development.

---------------------------------------------------------
Title: The Pre- and Post-Launch Configuration of a CME Flux Rope
Authors: Howard, T. A.; DeForest, C. E.
2014AGUFMSH13A4082H Altcode:
While the standard picture of a coronal mass ejection (CME) remains
largely unchanged from the early 1990s, we continue to develop our
understanding of the finer structures comprising the CME anatomy. Our
efforts are impeded by an assortment of inconveniences involving the
detection and tracking of CMEs: namely that they are two-dimensional
manifestations of an extended three-dimensional structure, they are
optically-thin, have asymmetric geometries that evolve at different
kinematic rates, and when observed by coronagraphs their appearances
are subject to the laws of Thomson scattering. Even in the STEREO
era we have rarely had an opportunity to explore in 3-D the finer
structures comprising CMEs and their greater counterparts. Through
careful analysis of a CME observed during such an opportunity,
we have constructed a detailed narrative describing the pre-launch
configuration of the magnetic configuration that gave rise to the CME,
and its launch and evolution through the corona and solar wind. We
present our narrative using observational evidence from EUV imagers,
coronagraphs and heliospheric imagers. We offer insight into the
implications of its 3-D structure for CME observation, including the
difficulties presented by geometry, kinematics and Thomson scattering.

---------------------------------------------------------
Title: Hi-C Observations and the Structure of Coronal Loops
Authors: DeForest, C. E.; Klimchuk, J. A.
2014AGUFMSH31C..04D Altcode:
Despite nearly four decades of study since the launch of Skylab, the
physical structure of coronal loops remains an enigma. Loops are guided
by the magnetic field and, in the common EUV emission lines, appear
to be composed of stranded structures reminiscent of field lines. This
stranded structure appears to have constant or nearly-constant width,
at odds with naive understanding of flux tube behavior in a field
gradient. Possible explanations range from physical solutions such as
twisted magnetic structure or peculiar properties of separators and
quasi-separators, to observation effects that invoke finite resolution
or anisotropy of the field containing each strand. The uncertainty
affects many aspects of basic coronal physics, because some of the
possible explanations for stranded structure have strong implications
for other mysteries such as the anomalously tall scale height of the
EUV corona. The Hi-C EUV images are the highest resolution coronal
images to date, and offer new insights into the structure of coronal
loops. We present an overview of research to date, show results from
a detailed analysis of several dozen well-presented loops that are
visible in the Hi-C data set, and speculate on the implications for
the rest of the corona.

---------------------------------------------------------
Title: The High-Resolution Coronal Imager (Hi-C)
Authors: Kobayashi, Ken; Cirtain, Jonathan; Winebarger, Amy R.;
Korreck, Kelly; Golub, Leon; Walsh, Robert W.; De Pontieu, Bart;
DeForest, Craig; Title, Alan; Kuzin, Sergey; Savage, Sabrina; Beabout,
Dyana; Beabout, Brent; Podgorski, William; Caldwell, David; McCracken,
Kenneth; Ordway, Mark; Bergner, Henry; Gates, Richard; McKillop,
Sean; Cheimets, Peter; Platt, Simon; Mitchell, Nick; Windt, David
2014SoPh..289.4393K Altcode: 2014SoPh..tmp..104K
The High-Resolution Coronal Imager (Hi-C) was flown on a NASA sounding
rocket on 11 July 2012. The goal of the Hi-C mission was to obtain
high-resolution (≈ 0.3 - 0.4”), high-cadence (≈ 5 seconds)
images of a solar active region to investigate the dynamics of solar
coronal structures at small spatial scales. The instrument consists of
a normal-incidence telescope with the optics coated with multilayers
to reflect a narrow wavelength range around 19.3 nm (including the
Fe XII 19.5-nm spectral line) and a 4096×4096 camera with a plate
scale of 0.1” pixel−1. The target of the Hi-C rocket
flight was Active Region 11520. Hi-C obtained 37 full-frame images
and 86 partial-frame images during the rocket flight. Analysis of the
Hi-C data indicates the corona is structured on scales smaller than
currently resolved by existing satellite missions.

---------------------------------------------------------
Title: The Formation and Launch of a Coronal Mass Ejection Flux Rope:
A Narrative Based on Observations
Authors: Howard, T. A.; DeForest, C. E.
2014ApJ...796...33H Altcode:
We present a data-driven narrative of the launch and early evolution
of the magnetic structure that gave rise to the coronal mass ejection
(CME) on 2008 December 12. The structure formed on December 7 and
launched early on December 12. We interpret this structure as a flux
rope based on prelaunch morphology, postlaunch magnetic measurements,
and the lack of large-scale magnetic reconnection signatures at
launch. We ascribe three separate onset mechanisms to the complete
disconnection of the flux rope from the Sun. It took 19 hr for the
flux rope to be fully removed from the Sun, by which time the segment
that first disconnected was around 40 R ⊙ away. This
implies that the original flux rope was stretched or broken; we
provide evidence for a possible bisection. A transient dark arcade
was observed on the Sun that was later obscured by a bright arcade,
which we interpret as the strapping field stretching and magnetically
reconnecting as it disconnected from the coronal field. We identify
three separate structures in coronagraph images to be manifestations
of the same original flux rope, and we describe the implications
for CME interpretation. We cite the rotation in the central flux
rope vector of the magnetic clouds observed in situ by ACE/Wind and
STEREO-B as evidence of the kink instability of the eastern segment
of the flux rope. Finally, we discuss possible alternative narratives,
including multiple prelaunch magnetic structures and the nonflux rope
scenario. Our results support the view that, in at least some CMEs,
flux rope formation occurs before launch.

---------------------------------------------------------
Title: Spatial Nonlocality of the Small-scale Solar Dynamo
Authors: Lamb, D. A.; Howard, T. A.; DeForest, C. E.
2014ApJ...788....7L Altcode: 2014arXiv1404.3259L
We explore the nature of the small-scale solar dynamo by tracking
magnetic features. We investigate two previously explored categories
of the small-scale solar dynamo: shallow and deep. Recent modeling
work on the shallow dynamo has produced a number of scenarios for how a
strong network concentration can influence the formation and polarity of
nearby small-scale magnetic features. These scenarios have measurable
signatures, for which we test using magnetograms from the Narrowband
Filter Imager (NFI) on board Hinode. We find no statistical tendency for
newly formed magnetic features to cluster around or away from network
concentrations, nor do we find any statistical relationship between
their polarities. We conclude that there is no shallow or "surface"
dynamo on the spatial scales observable by Hinode/NFI. In light of
these results, we offer a scenario in which the subsurface field in a
deep solar dynamo is stretched and distorted via turbulence, allowing
the small-scale field to emerge at random locations on the photosphere.

---------------------------------------------------------
Title: The Turbulent Origin of the Slow Solar Wind
Authors: DeForest, Craig; Matthaeus, Bill; Howard, Tim A.
2014AAS...22432363D Altcode:
We report on preliminary analyses of early solar wind turbulence via
heliospheric imaging: both the brightness structure function in the
STEREO-A HI-1 field of view and paths taken by individual boli of
comet-tail material in the solar wind. The analyses are complementary
and preliminary results indicate that turbulent processing is underway
even within the early HI-1 field of view (as low as 20-30 Rs).

---------------------------------------------------------
Title: Inbound Waves in the Solar Corona: A Direct Indicator of
Alfvén Surface Location
Authors: DeForest, C. E.; Howard, T. A.; McComas, D. J.
2014ApJ...787..124D Altcode: 2014arXiv1404.3235D
The tenuous supersonic solar wind that streams from the top of the
corona passes through a natural boundary—the Alfvén surface—that
marks the causal disconnection of individual packets of plasma and
magnetic flux from the Sun itself. The Alfvén surface is the locus
where the radial motion of the accelerating solar wind passes the radial
Alfvén speed, and therefore any displacement of material cannot carry
information back down into the corona. It is thus the natural outer
boundary of the solar corona and the inner boundary of interplanetary
space. Using a new and unique motion analysis to separate inbound and
outbound motions in synoptic visible-light image sequences from the
COR2 coronagraph on board the STEREO-A spacecraft, we have identified
inbound wave motion in the outer corona beyond 6 solar radii for the
first time and used it to determine that the Alfvén surface is at
least 12 solar radii from the Sun over the polar coronal holes and 15
solar radii in the streamer belt, well beyond the distance planned for
NASA's upcoming Solar Probe Plus mission. To our knowledge, this is
the first measurement of inbound waves in the outer solar corona and
the first direct measurement of lower bounds for the Alfvén surface.

---------------------------------------------------------
Title: Observing MHD Waves in the Solar Wind Acceleration Region
Authors: DeForest, Craig; McComas, Dave; Howard, Tim A.
2014AAS...22440801D Altcode:
We have, for the first time, observed and characterized compressive
waves propagating both outward and inward in the outer solar corona
above 4 Rs. In addition to detecting the waves, we have used them to
measure outflow in the all-important wind acceleration region. Because
the corona is an MHD system, any disturbance in the corona launches
low-frequency waves that propagate at the familiar MHD speeds
and serve to communicate that disturbance to other parts of the
system. Through careful filtration of synoptic STEREO-A/COR-2 data,
we have been able to measure both inbound and outbound waves at all
locations in the solar corona. By measuring in/out asymmetries in
the wave characteristics we have been able to estimate the solar wind
acceleration profile. Further, we are able to estimate the location
of the Alfvén surface - the hard-to-measure transition between the
corona and the superalfvénic solar wind, and the boundary at which
solar magnetic field lines transition from "closed" to "open". There
is a great deal of work to be done beyond these preliminary results,
which - it is hoped - open a new avenue for understanding coronal
dynamics and the origin of the solar wind.

---------------------------------------------------------
Title: Sparkling Extreme-ultraviolet Bright Dots Observed with Hi-C
Authors: Régnier, S.; Alexander, C. E.; Walsh, R. W.; Winebarger,
A. R.; Cirtain, J.; Golub, L.; Korreck, K. E.; Mitchell, N.; Platt,
S.; Weber, M.; De Pontieu, B.; Title, A.; Kobayashi, K.; Kuzin, S.;
DeForest, C. E.
2014ApJ...784..134R Altcode: 2014arXiv1402.2457R
Observing the Sun at high time and spatial scales is a step toward
understanding the finest and fundamental scales of heating events
in the solar corona. The high-resolution coronal (Hi-C) instrument
has provided the highest spatial and temporal resolution images of
the solar corona in the EUV wavelength range to date. Hi-C observed
an active region on 2012 July 11 that exhibits several interesting
features in the EUV line at 193 Å. One of them is the existence
of short, small brightenings "sparkling" at the edge of the active
region; we call these EUV bright dots (EBDs). Individual EBDs have a
characteristic duration of 25 s with a characteristic length of 680
km. These brightenings are not fully resolved by the SDO/AIA instrument
at the same wavelength; however, they can be identified with respect
to the Hi-C location of the EBDs. In addition, EBDs are seen in other
chromospheric/coronal channels of SDO/AIA, which suggests a temperature
between 0.5 and 1.5 MK. Based on their frequency in the Hi-C time
series, we define four different categories of EBDs: single peak,
double peak, long duration, and bursty. Based on a potential field
extrapolation from an SDO/HMI magnetogram, the EBDs appear at the
footpoints of large-scale, trans-equatorial coronal loops. The Hi-C
observations provide the first evidence of small-scale EUV heating
events at the base of these coronal loops, which have a free magnetic
energy of the order of 1026 erg.

---------------------------------------------------------
Title: The Future of Heliospheric Imaging
Authors: DeForest, Craig
2014cosp...40E.659D Altcode:
Heliospheric Imaging uses Thomson scattering to image structures in the
solar wind plasma, revealing morphology and total density of features
that previously were visible only through a combination of imagination
and inference from a few timeseries of in-situ measurements. With
the first successful routine, quantitative imaging of solar wind
features by emph{STEREO}/HI it is time to consider the next generation
of heliospheric imaging instruments to improve and exploit the
techniques opened by STEREO. Higher sensitivity, higher resolution,
and polarization measurements are obvious desiderata. Further, each
heliospheric imaging instrument built to date has revealed surprising
and counter-intuitive limitations and advantages of particular
techniques. I will summarize important lessons learned from past
and current heliospheric imaging instruments, directions in which
those instruments can and should be improved, and ideas for the next
generation of imagers.

---------------------------------------------------------
Title: Understanding CME Propagation through Combined Imaging and
In-Situ Measurements
Authors: DeForest, Craig; Howard, Timothy
2014cosp...40E.658D Altcode:
NASA's STEREO mission is the first observatory to track CMEs
approximately continuously from their pre-initiation state in
the corona to impact with in-situ probes near 1 AU from the Sun,
via direct imaging of Thomson-scattered light. This affords positive
identification of structures detected in-situ, with particular features
in the pre-eruption solar corona. It also permits, for the first time,
direct observation of the morphology and evolution of CMEs as they
propagate and interact with the surrounding media in interplanetary
space. We report on recent results obtained by tracking CMEs and other
ejecta from the corona to impact with in-situ probes, discuss their
importance to understanding the relationship between solar activity
and geospace events, and present ideas for future measurements to
improve on these results.

---------------------------------------------------------
Title: Asymmetry of the Mars Ionosphere Boundary Altitude during a
Solar Energetic Particle Event
Authors: Frahm, R. A.; Elliott, H. A.; Winningham, J. D.; Sharber,
J. R.; DeForest, C. E.; Howard, T. A.; Kallio, E. J.; McKenna-Lawlor,
S.; Duru, F.; Morgan, D. D.; Coates, A. J.; Odstrcil, D.; Lundin,
R. N.; Futaana, Y.; Barabash, S. V.
2013AGUFM.P21A1712F Altcode:
The Electron Spectrometer (ELS) and the Ion Mass Spectrometer (IMA)
from the Analyzer of Space Plasmas and Energetic Atoms (ASPERA-3)
experiment on the ESA's Mars Express (MEx) spacecraft have been used
to study a Solar Energetic Particle (SEP) event associated with a
Class X solar flare on on January 27, 2012. Arrival of the SEP at Mars
about 46 minutes later is observed as an increase in the background
of these plasma instruments. The background counts were observed to
increase sharply, followed by a gradual decrease that lasted for about
4 days. During this time, ELS and IMA also recorded passages across
the Martian ionospheric boundary on the dusk side of the planet,
twice during each MEx orbit. The altitude of the ionospheric boundary
was thereby found to have behaved differently in the northern and
southern hemispheres. The boundary increased in altitude in each
hemisphere with a time delay as the flare pumped energy into the
Mars system. After reaching peak altitude, the ionospheric boundary
returned to its original configuration faster in the northern than
in the southern hemisphere. This suggests that the main difference
between the northern and southern hemispheres at Mars, namely the
presence in the south of crustal magnetic fields, is responsible for
the dissipation of the energy input at a slower rate in the southern
than in the northern hemisphere.

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Title: Anti-parallel EUV Flows Observed along Active Region Filament
Threads with Hi-C
Authors: Alexander, Caroline E.; Walsh, Robert W.; Régnier, Stéphane;
Cirtain, Jonathan; Winebarger, Amy R.; Golub, Leon; Kobayashi,
Ken; Platt, Simon; Mitchell, Nick; Korreck, Kelly; DePontieu, Bart;
DeForest, Craig; Weber, Mark; Title, Alan; Kuzin, Sergey
2013ApJ...775L..32A Altcode: 2013arXiv1306.5194A
Plasma flows within prominences/filaments have been observed for
many years and hold valuable clues concerning the mass and energy
balance within these structures. Previous observations of these flows
primarily come from Hα and cool extreme-ultraviolet (EUV) lines (e.g.,
304 Å) where estimates of the size of the prominence threads has been
limited by the resolution of the available instrumentation. Evidence of
"counter-steaming" flows has previously been inferred from these cool
plasma observations, but now, for the first time, these flows have been
directly imaged along fundamental filament threads within the million
degree corona (at 193 Å). In this work, we present observations
of an AR filament observed with the High-resolution Coronal Imager
(Hi-C) that exhibits anti-parallel flows along adjacent filament
threads. Complementary data from the Solar Dynamics Observatory
(SDO)/Atmospheric Imaging Assembly (AIA) and Helioseismic and Magnetic
Imager are presented. The ultra-high spatial and temporal resolution
of Hi-C allow the anti-parallel flow velocities to be measured (70-80
km s-1) and gives an indication of the resolvable thickness
of the individual strands (0.”8 ± 0.”1). The temperature of the
plasma flows was estimated to be log T (K) = 5.45 ± 0.10 using Emission
Measure loci analysis. We find that SDO/AIA cannot clearly observe these
anti-parallel flows or measure their velocity or thread width due to
its larger pixel size. We suggest that anti-parallel/counter-streaming
flows are likely commonplace within all filaments and are currently
not observed in EUV due to current instrument spatial resolution.

---------------------------------------------------------
Title: Decline and Recovery of the Interplanetary Magnetic Field
during the Protracted Solar Minimum
Authors: Smith, Charles W.; Schwadron, Nathan A.; DeForest, Craig E.
2013ApJ...775...59S Altcode:
The interplanetary magnetic field (IMF) is determined by the amount of
solar magnetic flux that passes through the top of the solar corona into
the heliosphere, and by the dynamical evolution of that flux. Recently,
it has been argued that the total flux of the IMF evolves over the
solar cycle due to a combination of flux that extends well outside of
1 AU and is associated with the solar wind, and additionally, transient
flux associated with coronal mass ejections (CMEs). In addition to the
CME eruption rate, there are three fundamental processes involving
conversion of magnetic flux (from transient to wind-associated),
disconnection, and interchange reconnection that control the levels
of each form of magnetic flux in the interplanetary medium. This is
distinct from some earlier models in which the wind-associated component
remains steady across the solar cycle. We apply the model of Schwadron
et al. that quantifies the sources, interchange, and losses of magnetic
flux to 50 yr of interplanetary data as represented by the Omni2 data
set using the sunspot number as a proxy for the CME eruption rate. We do
justify the use of that proxy substitution. We find very good agreement
between the predicted and observed interplanetary magnetic flux. In the
absence of sufficient CME eruptions, the IMF falls on the timescale
of ~6 yr. A key result is that rising toroidal flux resulting from
CME eruption predates the increase in wind-associated IMF.

---------------------------------------------------------
Title: Solar Magnetic Tracking. IV. The Death of Magnetic Features
Authors: Lamb, D. A.; Howard, T. A.; DeForest, C. E.; Parnell, C. E.;
Welsch, B. T.
2013ApJ...774..127L Altcode: 2013arXiv1307.4019L
The removal of magnetic flux from the quiet-Sun photosphere is
important for maintaining the statistical steady state of the magnetic
field there, for determining the magnetic flux budget of the Sun,
and for estimating the rate of energy injected into the upper solar
atmosphere. Magnetic feature death is a measurable proxy for the
removal of detectable flux, either by cancellation (submerging or
rising loops, or reconnection in the photosphere) or by dispersal
of flux. We used the SWAMIS feature tracking code to understand how
nearly 2 × 104 magnetic features die in an hour-long
sequence of Hinode/SOT/NFI magnetograms of a region of the quiet
Sun. Of the feature deaths that remove visible magnetic flux from the
photosphere, the vast majority do so by a process that merely disperses
the previously detected flux so that it is too small and too weak
to be detected, rather than completely eliminating it. The behavior
of the ensemble average of these dispersals is not consistent with
a model of simple planar diffusion, suggesting that the dispersal is
constrained by the evolving photospheric velocity field. We introduce
the concept of the partial lifetime of magnetic features, and show
that the partial lifetime due to Cancellation of magnetic flux, 22 hr,
is three times slower than previous measurements of the flux turnover
time. This indicates that prior feature-based estimates of the flux
replacement time may be too short, in contrast with the tendency
for this quantity to decrease as resolution and instrumentation have
improved. This suggests that dispersal of flux to smaller scales is
more important for the replacement of magnetic fields in the quiet
Sun than observed bipolar cancellation. We conclude that processes
on spatial scales smaller than those visible to Hinode dominate the
processes of flux emergence and cancellation, and therefore also the
quantity of magnetic flux that threads the photosphere.

---------------------------------------------------------
Title: Structure of solar coronal loops: from miniature to large-scale
Authors: Peter, H.; Bingert, S.; Klimchuk, J. A.; de Forest, C.;
Cirtain, J. W.; Golub, L.; Winebarger, A. R.; Kobayashi, K.; Korreck,
K. E.
2013A&A...556A.104P Altcode: 2013arXiv1306.4685P
 Aims: We use new data from the High-resolution Coronal Imager
(Hi-C) with its unprecedented spatial resolution of the solar corona
to investigate the structure of coronal loops down to 0.2”. 
Methods: During a rocket flight, Hi-C provided images of the solar
corona in a wavelength band around 193 Å that is dominated by emission
from Fe xii showing plasma at temperatures around 1.5 MK. We analyze
part of the Hi-C field-of-view to study the smallest coronal loops
observed so far and search for the possible substructuring of larger
loops. Results: We find tiny 1.5 MK loop-like structures that
we interpret as miniature coronal loops. Their coronal segments above
the chromosphere have a length of only about 1 Mm and a thickness of
less than 200 km. They could be interpreted as the coronal signature
of small flux tubes breaking through the photosphere with a footpoint
distance corresponding to the diameter of a cell of granulation. We
find that loops that are longer than 50 Mm have diameters of about 2”
or 1.5 Mm, which is consistent with previous observations. However, Hi-C
really resolves these loops with some 20 pixels across the loop. Even
at this greatly improved spatial resolution, the large loops seem to
have no visible substructure. Instead they show a smooth variation in
cross-section. Conclusions: That the large coronal loops do not
show a substructure on the spatial scale of 0.1” per pixel implies that
either the densities and temperatures are smoothly varying across these
loops or it places an upper limit on the diameter of the strands the
loops might be composed of. We estimate that strands that compose the
2” thick loop would have to be thinner than 15 km. The miniature loops
we find for the first time pose a challenge to be properly understood
through modeling. Appendices are available in electronic form at
<A href="http://www.aanda.org">http://www.aanda.org</A>

---------------------------------------------------------
Title: STEREO/SECCHI Level 2 Heliospheric Data: Status and
Availability
Authors: DeForest, Craig; Howard, T. A.
2013SPD....44..132D Altcode:
We are currently processing the STEREO/SECCHI heliospheric imaging data
to separate the starfield, and depositing them into the SDAC and STEREO
data repository. We present an overview of the data, the quality, how
to use (and how not to overinterpret) them scientifically, and status
of the processing project.Abstract (2,250 Maximum Characters): We are
currently processing the STEREO/SECCHI heliospheric imaging data to
separate the starfield, and depositing them into the SDAC and STEREO
data repository. We present an overview of the data, the quality,
how to use (and how not to overinterpret) them scientifically, and
status of the processing project.

---------------------------------------------------------
Title: Detecting Nanoflare Heating Events in Subarcsecond Inter-moss
Loops Using Hi-C
Authors: Winebarger, Amy R.; Walsh, Robert W.; Moore, Ronald;
De Pontieu, Bart; Hansteen, Viggo; Cirtain, Jonathan; Golub, Leon;
Kobayashi, Ken; Korreck, Kelly; DeForest, Craig; Weber, Mark; Title,
Alan; Kuzin, Sergey
2013ApJ...771...21W Altcode:
The High-resolution Coronal Imager (Hi-C) flew aboard a NASA sounding
rocket on 2012 July 11 and captured roughly 345 s of high-spatial and
temporal resolution images of the solar corona in a narrowband 193 Å
channel. In this paper, we analyze a set of rapidly evolving loops that
appear in an inter-moss region. We select six loops that both appear in
and fade out of the Hi-C images during the short flight. From the Hi-C
data, we determine the size and lifetimes of the loops and characterize
whether these loops appear simultaneously along their length or
first appear at one footpoint before appearing at the other. Using
co-aligned, co-temporal data from multiple channels of the Atmospheric
Imaging Assembly on the Solar Dynamics Observatory, we determine the
temperature and density of the loops. We find the loops consist of
cool (~105 K), dense (~1010 cm-3)
plasma. Their required thermal energy and their observed evolution
suggest they result from impulsive heating similar in magnitude to
nanoflares. Comparisons with advanced numerical simulations indicate
that such dense, cold and short-lived loops are a natural consequence
of impulsive magnetic energy release by reconnection of braided magnetic
field at low heights in the solar atmosphere.

---------------------------------------------------------
Title: Remotely Measuring Features in the Solar Wind Using Polarimetry
Authors: Howard, Tim A.; DeForest, C.; Odstrcil, D.
2013SPD....44..124H Altcode:
The theory of Thomson scattering, while well understood when applied
to features observed in the corona, has been misunderstood by many
when applied to features in the heliosphere. The confusion arises
when assumptions applied to analyzing coronagraph data are extended to
heliospheric imagers, where the consequences of the theory are somewhat
different. Two crucial problems are the assumption of close proximity to
the Thomson surface and detectability being governed by the background
F and K corona. We demonstrate that these assumptions do not apply
to heliospheric imagers. Further, we explore polarized heliospheric
imaging in the context of transient feature detection. We show that
not only are features detectable above the background, but also that
additional information on transients such as coronal mass ejections can
be extracted from a combination of polarized and unpolarized images than
from unpolarized imaging alone.Abstract (2,250 Maximum Characters):
The theory of Thomson scattering, while well understood when applied
to features observed in the corona, has been misunderstood by many
when applied to features in the heliosphere. The confusion arises
when assumptions applied to analyzing coronagraph data are extended
to heliospheric imagers, where the consequences of the theory are
somewhat different. Two crucial problems are the assumption of close
proximity to the Thomson surface and detectability being governed by
the background F and K corona. We demonstrate that these assumptions
do not apply to heliospheric imagers. Further, we explore polarized
heliospheric imaging in the context of transient feature detection. We
show that not only are features detectable above the background,
but also that additional information on transients such as coronal
mass ejections can be extracted from a combination of polarized and
unpolarized images than from unpolarized imaging alone.

---------------------------------------------------------
Title: The Launch and Early Evolution of a CME Flux Rope
Authors: Howard, Tim A.; DeForest, C.
2013SPD....44...14H Altcode:
We present a narrative of the launch and early evolution of a flux rope
comprised within the coronal mass ejection (CME) that left the Sun on
12 December 2008. The two STEREO spacecraft were near quadrature at
that time, so we were afforded a unique view of this flux rope from
along its edge and down its barrel simultaneously using STEREO's
EUVI cameras. We find that a sequence of seemingly separate CMEs
observed in the corona and solar wind were actually manifestations
of the same flux rope passing through the imagers' fields of view at
different times. The launch begins with a small solar flare at the
northern-most end of a pre-formed flux rope, which lifts off from
this end first via the tether-cutting mechanism. Other segments of
the flux rope follow this launch, and a filament is observed to roll
over the top of these segments and pour back into the solar disk,
thereby indicating the mass draining mechanism at play. The southern
end of the flux rope remains fixed to the Sun, leading to an eventual
stress-fracture and bisection of the flux rope. The severed southern
end eventually disconnects from the Sun a day later via what appears
to be the kink instability mechanism. This narrative, describing the
interplay between three separate onset mechanisms for simple CME during
a period of extremely low solar activity, demonstrates the complexity
of the physics of CME onset.

---------------------------------------------------------
Title: Imaging the Inner Boundary of the Solar Wind
Authors: DeForest, Craig; Howard, T. A.; Matthaeus, W. H.
2013SPD....44..131D Altcode:
We have begun analyzing photometric background-subtracted images from
STEREO/SECCHI's HI-1 instrument. The images show a clear "flocculated"
pattern to the solar wind that is reminiscent of more familiar turbulent
flows and more uniformly structured than the top of the corona seen with
LASCO C-3 or STEREO/SECCHI COR2. We will present initial quantitative
results of this analysis, indicating whether the flocculation pattern
is produced locally or advected intact from the corona. This bears
heavily on the question of the origin of the variable slow solar wind.

---------------------------------------------------------
Title: Progress toward high resolution EUV spectroscopy
Authors: Korendyke, C.; Doschek, G. A.; Warren, H.; Young, P. R.;
Chua, D.; Hassler, D. M.; Landi, E.; Davila, J. M.; Klimchuck, J.;
Tun, S.; DeForest, C.; Mariska, J. T.; Solar C Spectroscopy Working
Group; LEMUR; EUVST Development Team
2013SPD....44..143K Altcode:
HIgh resolution EUV spectroscopy is a critical instrumental technique
to understand fundamental physical processes in the high temperature
solar atmosphere. Spectroscopic observations are used to measure
differential emission measure, line of sight and turbulent flows,
plasma densities and emission measures. Spatially resolved, spectra of
these emission lines with adequate cadence will provide the necessary
clues linking small scale structures with large scale, energetic
solar phenomena. The necessary observations to determine underlying
physical processes and to provide comprehensive temperature coverage
of the solar atmosphere above the chromosphere will be obtained by the
proposed EUVST instrument for Solar C. This instrument and its design
will be discussed in this paper. Progress on the VEry high Resolution
Imaging Spectrograph (VERIS) sounding rocket instrument presently under
development at the Naval Research Laboratory will also be discussed.

---------------------------------------------------------
Title: Update on SWAMIS Emerging Flux Detection and Magnetic Feature
Tracking for SDO/HMI
Authors: Lamb, Derek; DeForest, C.; Davey, A. R.; Timmons, R.
2013SPD....44..100L Altcode:
The SWAMIS-EF emerging magnetic flux detection algorithm has been
operating in the SDO/HMI data pipeline since 2011. We present an
update on the status of the module and improvements to the algorithm
since it began reporting Emerging Flux HEK events. We will show
detailed examples of emerging flux events, and provide some summary
information. Finally, we will provide an update on the state of
SWAMIS magnetic feature tracking for full-disk, full-resolution HMI
line-of-sight magnetograms.Abstract (2,250 Maximum Characters): The
SWAMIS-EF emerging magnetic flux detection algorithm has been operating
in the SDO/HMI data pipeline since 2011. We present an update on the
status of the module and improvements to the algorithm since it began
reporting Emerging Flux HEK events. We will show detailed examples of
emerging flux events, and provide some summary information. Finally,
we will provide an update on the state of SWAMIS magnetic feature
tracking for full-disk, full-resolution HMI line-of-sight magnetograms.

---------------------------------------------------------
Title: Status of RAISE, the Rapid Acquisition Imaging Spectrograph
Experiment
Authors: Laurent, Glenn T.; Hassler, D. M.; DeForest, C.; Ayres,
T. R.; Davis, M.; De Pontieu, B.; Schuehle, U.; Warren, H.
2013SPD....44..145L Altcode:
The Rapid Acquisition Imaging Spectrograph Experiment (RAISE) sounding
rocket payload is a high speed scanning-slit imaging spectrograph
designed to observe the dynamics and heating of the solar chromosphere
and corona on time scales as short as 100 ms, with 1 arcsec spatial
resolution and a velocity sensitivity of 1-2 km/s. The instrument is
based on a new class of UV/EUV imaging spectrometers that use only
two reflections to provide quasi-stigmatic performance simultaneously
over multiple wavelengths and spatial fields. The design uses an
off-axis parabolic telescope mirror to form a real image of the sun
on the spectrometer entrance aperture. A slit then selects a portion
of the solar image, passing its light onto a near-normal incidence
toroidal grating, which re-images the spectrally dispersed radiation
onto two array detectors. Two full spectral passbands over the same
one-dimensional spatial field are recorded simultaneously with no
scanning of the detectors or grating. The two different spectral
bands (1st-order 1205-1243Å and 1526-1564Å) are imaged onto two
intensified Active Pixel Sensor (APS) detectors whose focal planes are
individually adjusted for optimized performance. The telescope and
grating are coated with B4C to enhance short wavelength (2nd order)
reflectance, enabling the instrument to record the brightest lines
between 602-622Å and 761-780Å at the same time. RAISE reads out the
full field of both detectors at 5-10 Hz, allowing us to record over
1,500 complete spectral observations in a single 5-minute rocket flight,
opening up a new domain of high time resolution spectral imaging and
spectroscopy. We present an overview of the project, a summary of the
maiden flight results, and an update on instrument status.Abstract
(2,250 Maximum Characters): The Rapid Acquisition Imaging Spectrograph
Experiment (RAISE) sounding rocket payload is a high speed scanning-slit
imaging spectrograph designed to observe the dynamics and heating of the
solar chromosphere and corona on time scales as short as 100 ms, with 1
arcsec spatial resolution and a velocity sensitivity of 1-2 km/s. The
instrument is based on a new class of UV/EUV imaging spectrometers
that use only two reflections to provide quasi-stigmatic performance
simultaneously over multiple wavelengths and spatial fields. The design
uses an off-axis parabolic telescope mirror to form a real image of
the sun on the spectrometer entrance aperture. A slit then selects
a portion of the solar image, passing its light onto a near-normal
incidence toroidal grating, which re-images the spectrally dispersed
radiation onto two array detectors. Two full spectral passbands over
the same one-dimensional spatial field are recorded simultaneously with
no scanning of the detectors or grating. The two different spectral
bands (1st-order 1205-1243Å and 1526-1564Å) are imaged onto two
intensified Active Pixel Sensor (APS) detectors whose focal planes are
individually adjusted for optimized performance. The telescope and
grating are coated with B4C to enhance short wavelength (2nd order)
reflectance, enabling the instrument to record the brightest lines
between 602-622Å and 761-780Å at the same time. RAISE reads out the
full field of both detectors at 5-10 Hz, allowing us to record over
1,500 complete spectral observations in a single 5-minute rocket flight,
opening up a new domain of high time resolution spectral imaging and
spectroscopy. We present an overview of the project, a summary of the
maiden flight results, and an update on instrument status.

---------------------------------------------------------
Title: Observations of Synchronous Magnetic Flux Emergence
Authors: Lamb, Derek; DeForest, C.
2013SPD....44..106L Altcode:
We report on observations of spatially-separated, nearly simultaneous
small-scale magnetic flux emergence seen in SDO/HMI magnetograms. In the
prototypical event, two pairs of bipoles emerge with a nearly identical
north-south orientation, the beginning of the separate emergence
events begins within 3 hours of each other, and the distance between
the pair is approximately twice the bipolar separation distance. This
suggests a common subsurface origin. We present a detailed analysis
of this emergence event and the associated evolving coronal magnetic
field topology, show other examples of similar events, and present
a preliminary statistical analysis of the likelihood of such events
occurring by chance.

---------------------------------------------------------
Title: The Onset, Evolution, and Solar Connectivity of a Slow Coronal
Mass Ejection
Authors: Howard, Tim A.; DeForest, Craig E.; McComas, David J.
2013shin.confE.144H Altcode:
We have combined new remote sensing images with near-Earth in-situ
datasets to track a complete CME from its onset in the low corona
through the inner heliosphere to 1 AU. This CME, observed in December
2008, is slow, and erupted during the lowest activity interval of the
last solar minimum. We observe the launch of the initial flux rope
and its likely launch mechanisms, identify the magnetic structures
both within and surrounding the flux rope, and track their behavior
to 1 AU where they are confirmed using solar wind, IMF, and energetic
particle in-situ data. We find that the magnetic structure consists of
the flux rope core surrounded by layers of fields that are connected
to the Sun in a variety of ways. Moving outwards from the core we find
a doubly-connected `strapping' field, surrounded by a closed `coronal
sheath', which in turn pushes against a draping singly-connected `wind
sheath'. All of these structures are observed at 1 AU, indicating that
at least for this slow CME the strapping field was stretched out to
large distances.

---------------------------------------------------------
Title: Observing Coronal Nanoflares in Active Region Moss
Authors: Testa, Paola; De Pontieu, Bart; Martínez-Sykora, Juan;
DeLuca, Ed; Hansteen, Viggo; Cirtain, Jonathan; Winebarger, Amy;
Golub, Leon; Kobayashi, Ken; Korreck, Kelly; Kuzin, Sergey; Walsh,
Robert; DeForest, Craig; Title, Alan; Weber, Mark
2013ApJ...770L...1T Altcode: 2013arXiv1305.1687T
The High-resolution Coronal Imager (Hi-C) has provided Fe XII 193Å
images of the upper transition region moss at an unprecedented spatial
(~0.”3-0.”4) and temporal (5.5 s) resolution. The Hi-C observations
show in some moss regions variability on timescales down to ~15 s,
significantly shorter than the minute-scale variability typically found
in previous observations of moss, therefore challenging the conclusion
of moss being heated in a mostly steady manner. These rapid variability
moss regions are located at the footpoints of bright hot coronal
loops observed by the Solar Dynamics Observatory/Atmospheric Imaging
Assembly in the 94 Å channel, and by the Hinode/X-Ray Telescope. The
configuration of these loops is highly dynamic, and suggestive of
slipping reconnection. We interpret these events as signatures of
heating events associated with reconnection occurring in the overlying
hot coronal loops, i.e., coronal nanoflares. We estimate the order
of magnitude of the energy in these events to be of at least a few
1023 erg, also supporting the nanoflare scenario. These
Hi-C observations suggest that future observations at comparable
high spatial and temporal resolution, with more extensive temperature
coverage, are required to determine the exact characteristics of the
heating mechanism(s).

---------------------------------------------------------
Title: The coronal mass ejection interaction with the induced
magnetosphere of Mars due to the 27 January 2012 solar storm
Authors: Frahm, R. A.; Sharber, J. R.; Winningham, J. D.; Elliott,
H. A.; Howard, T. A.; DeForest, C. E.; Odstrĉil, D.; Kallio, E.;
McKenna-Lawlor, S.; Barabash, S.
2013AIPC.1539..398F Altcode:
An X-class flare on 27 January 2012 generated a high-energy particle
stream advancing along the interplanetary magnetic field (IMF) which
arrived at Mars in about 39 minutes, with a coronal mass ejection
(CME) released from the same active region arriving at Mars several
days later. The Electron Spectrometer (ELS), part of the Analyzer
of Space Plasmas and Energetic Atoms (ASPERA-3) experiment on the
European Mars Express (MEx) Spacecraft, is used to show that the
effect of the CME plasma caused an increase in the intensity of the
electron distribution function within the Martian magnetosheath. Models
of this event predicted the speed, morphology, and Martian impact of
the CME. The Mars reaction, being an induced magnetosphere, responds
to changes in solar wind conditions by continually self adjusting its
magnetosheath to stand off the solar wind. Since the ion component of
the solar wind interaction carries momentum away from the Sun, it is
the electrons with their significantly greater mobility that must self
adjust in order to maintain charge neutrality and the proper induced
current flow in order to stand-off changes in the solar wind.

---------------------------------------------------------
Title: Solar energetic particle arrival at Mars due to the 27 January
2012 solar storm
Authors: Frahm, R. A.; Sharber, J. R.; Winningham, J. D.; Elliott,
H. A.; Howard, T. A.; DeForest, C. E.; Odstrĉil, D.; Kallio, E.;
McKenna-Lawlor, S.; Barabash, S.
2013AIPC.1539..394F Altcode:
On January 27, 2012, an X-class flare brightened on the Sun at 18:15
UT. This event was associated with the generation of a high-energy
stream of Solar Energetic Particles (SEPs) advancing along the
Interplanetary Magnetic Field (IMF) which arrived at Mars in about 39
minutes. A Coronal Mass Ejection (CME) arrived at Mars several days
later. The Electron Spectrometer (ELS), a part of the Analyzer of Space
Plasmas and Energetic Atoms (ASPERA-3) experiment on the European Mars
Express (MEx) Spacecraft, associatively detected elevated background
levels of penetrating particle radiation which abruptly increased
above the baseline level by two orders of magnitude within several
hours after first arrival, allowing the particle arrival time to be
accurately determined from this gradual SEP. As Mars reacted to the SEP,
the atmosphere heated driving expansion of the ionosphere.

---------------------------------------------------------
Title: The Detectability of Features in Unpolarized and Polarized
Heliospheric Imagers
Authors: Howard, Tim A.; DeForest, Craig E.; Odstrcil, Dusan
2013shin.confE..41H Altcode:
We explore the consequences of the theory of Thomson scattering on
the detectability of features observed by white light heliospheric
imagers. This involves a closer look at the so-called Thomson
surface, which represents a sphere describing the locus of points
along all lines of sight that are closest to the Sun. We describe
how the scattering physics acts to de-emphasize the importance of
the Thomson surface to feature detectability, where features are
observed with near-equal efficiency across a large range of angles
surrounding the surface. This gives rise to what we have termed the
`Thomson plateau', and we show how the analysis of features on the
plateau is reduced to problems of only density and geometry. Further,
we show how the plateau is eliminated when observing in polarized light,
and therefore how additional information about features can be extracted
using polarimetry rather than unpolarized imagery alone.

---------------------------------------------------------
Title: Exploring Polarized Heliospheric Imaging
Authors: Howard, T. A.; DeForest, C.; Tappin, S. J.; Odstrcil, D.
2013AGUSMSH42B..01H Altcode:
Heliospheric imagers (first SMEI then the HIs) currently involve
the imaging of unpolarized scattered light from free electrons in
the solar wind plasma. Heliospheric imager datasets have a number of
advantages over those of coronagraphs, primarily because of the broad
nature of the Thomson scattering function that we call the "Thomson
plateau". This means that the effects of scattering can be largely
ignored over large angular extents, thereby reducing the problem of
analysis to simply one of density and geometry. A further advantage that
is exploited with coronagraphs but not yet with heliospheric imagers
is with the use of polarimetry. Polarized images contain additional
directional information and reduce numerous background noise sources,
thereby enabling the extraction of additional information on coronal
mass ejections and other solar wind transients. Using examples of
polarized heliospheric images of a simulated CME, we explore how such
information could be extracted from a future polarizing heliospheric
imager for the utility of space weather forecasting.

---------------------------------------------------------
Title: Tracking Coronal Features from the Low Corona to Earth:
A Quantitative Analysis of the 2008 December 12 Coronal Mass Ejection
Authors: DeForest, C. E.; Howard, T. A.; McComas, D. J.
2013ApJ...769...43D Altcode:
We have tracked a slow magnetic cloud associated coronal mass ejection
(CME) continuously from its origin as a flux rope structure in the
low solar corona over a four-day passage to impact with spacecraft
located near Earth. Combining measurements from the STEREO, ACE,
and Wind space missions, we are able to follow major elements with
enough specificity to relate pre-CME coronal structure in the low
corona to the corresponding elements seen in the near-Earth in situ
data. Combining extreme ultraviolet imaging, quantitative Thomson
scattering data throughout the flight of the CME, and "ground-truth"
in situ measurements, we: (1) identify the plasma observed by ACE
and Wind with specific features in the solar corona (a segment of
a long flux rope); (2) determine the onset mechanism of the CME
(destabilization of a filament channel following flare reconnection,
coupled with the mass draining instability) and demonstrate that it is
consistent with the in situ measurements; (3) identify the origin of
different layers of the sheath material around the central magnetic
cloud (closed field lifted from the base of the corona, closed field
entrained during passage through the corona, and solar wind entrained
by the front of the CME); (4) measure mass accretion of the system
via snowplow effects in the solar wind as the CME crossed the solar
system; and (5) quantify the kinetic energy budget of the system in
interplanetary space, and determine that it is consistent with no
long-term driving force on the CME.

---------------------------------------------------------
Title: Imaging the Variable Solar Wind
Authors: DeForest, C.; Howard, T. A.; Matthaeus, W. H.
2013AGUSMSH31B..07D Altcode:
With the advent of wide-field Thomson scattering imagery from
STEREO/SECCHI, it is possible to image the solar wind continuously
from its origin in the low corona to large fractions of 1AU from the
Sun. Although it is sensitive only to non-stationary density structures,
Thomson imaging yields morphological insight and global perspective
that are not directly available from in-situ data. I will review recent
work on both large and small scale analysis. On large scales, it is now
possible to track well-presented CMEs from the pre-eruptive structure
to impact with in-situ probes, yielding positive identification of
flux rope structure based on both positively tracked morphology and
direct magnetic measurement. In some cases, plasma detected in-situ
can be positively identified with particular pieces of pre-eruptive
anatomy in the low corona. Some observed large-scale features are
as-yet unexplained. In quiet solar wind, small ejecta and blobs are
readily distinguished from disconnection events that may be identified
by their morphology, and all can be tracked through the Alfvén surface
boundary at 20-50 Rs into the solar wind proper. In the HI-1 field of
view, the solar wind takes on a flocculated appearance, though most
of the individual features lose image structure and cannot be tracked
across the entire field of view. Analysis of individual ejecta and
of the statistical properties of the flocculation pattern is yielding
insights into the nature of fluctuations and origin of variability in
the slow solar wind.

---------------------------------------------------------
Title: Plasma Characteristic Determination During the Coronal Mass
Ejection Associated with the January 27, 2012 Solar Storm
Authors: Frahm, Rudy A.; Howard, Timothy; DeForest, Craig; Odstrcil,
Dusan; Kallio, Esa; Mckenna-Lawler, Susan; Barabash, Stas; Winningham,
J. David; Sharber, James R.; Elliott, Heather A.
2013EGUGA..1514062F Altcode:
On January 27, 2012, an X-class flare was launched from the Sun at 18:15
UT. The X-class flare generated a high-energy particle stream flowing
along the Interplanetary Magnetic Field (IMF) which arrived at Mars
in about 39 minutes, with the resulting Coronal Mass Ejection (CME)
arriving at Mars several days later. The Electron Spectrometer (ELS),
part of the Analyzer of Space Plasmas and Energetic Atoms (ASPERA-3)
experiment on the European Mars Express (MEx) Spacecraft, is used
to show that the effect of the CME plasma caused an increase in the
intensity of the energy flux within the Martian magnetosheath. Models
of this event predicted the speed of the CME, which is used to identify
which increase of the magnetosheath signature is due to the CME relating
to this flare as several increases in Martian magnetosheath plasma
are observed during the flare period. The Mars reaction, being an
induced magnetosphere, responds to changes in solar wind conditions
by continually self adjusting its magnetosheath to stand off the
solar wind. Since the ion component of the solar wind interaction
carries momentum away from the Sun, it is the electrons which must
self adjust in order to maintain charge neutrality within the plasma
and the proper induced current flow in order to stand-off changes in
the solar wind. Here we examine the electron plasma properties during
the forward CME shock in the Martian magnetosheath and describe the
plasma conditions.

---------------------------------------------------------
Title: Point-spread Functions for the Extreme-ultraviolet Channels
of SDO/AIA Telescopes
Authors: Poduval, B.; DeForest, C. E.; Schmelz, J. T.; Pathak, S.
2013ApJ...765..144P Altcode:
We present the stray-light point-spread functions (PSFs) and their
inverses we characterized for the Atmospheric Imaging Assembly (AIA) EUV
telescopes on board the Solar Dynamics Observatory (SDO) spacecraft. The
inverse kernels are approximate inverses under convolution. Convolving
the original Level 1 images with them produces images with improved
stray-light characteristics. We demonstrate the usefulness of
these PSFs by applying them to two specific cases: photometry and
differential emission measure (DEM) analysis. The PSFs consist
of a narrow Gaussian core, a diffraction component, and a diffuse
component represented by the sum of a Gaussian-truncated Lorentzian
and a shoulder Gaussian. We determined the diffraction term using the
measured geometry of the diffraction pattern identified in flare images
and the theoretically computed intensities of the principal maxima of
the first few diffraction orders. To determine the diffuse component,
we fitted its parameterized model using iterative forward-modeling of
the lunar interior in the SDO/AIA images from the 2011 March 4 lunar
transit. We find that deconvolution significantly improves the contrast
in dark features such as miniature coronal holes, though the effect
was marginal in bright features. On a percentage-scattering basis,
the PSFs for SDO/AIA are better by a factor of two than that of the
EUV telescope on board the Transition Region And Coronal Explorer
mission. A preliminary analysis suggests that deconvolution alone does
not affect DEM analysis of small coronal loop segments with suitable
background subtraction. We include the derived PSFs and their inverses
as supplementary digital materials.

---------------------------------------------------------
Title: The Thomson Surface. II. Polarization
Authors: DeForest, C. E.; Howard, T. A.; Tappin, S. J.
2013ApJ...765...44D Altcode: 2012arXiv1207.5894D
The solar corona and heliosphere are visible via sunlight that is
Thomson-scattered off free electrons, yielding a radiance against
the celestial sphere. In this second part of a three-article series,
we discuss linear polarization of this scattered light parallel and
perpendicular to the plane of scatter in the context of heliospheric
imaging far from the Sun. The difference between these two radiances
(pB) varies quite differently with scattering angle, compared to the sum
that would be detected in unpolarized light (B). The difference between
these two quantities has long been used in a coronagraphic context for
background subtraction and to extract some three-dimensional information
about the corona; we explore how these effects differ in the wider-field
heliospheric imaging case where small-angle approximations do not
apply. We develop an appropriately simplified theory of polarized
Thomson scattering in the heliosphere, discuss signal-to-noise
considerations, invert the scattering equations analytically to solve
the three-dimensional object location problem for small objects,
discuss exploiting polarization for background subtraction, and
generate simple forward models of several classes of heliospheric
feature. We conclude that pB measurements of heliospheric material are
much more localized to the Thomson surface than are B measurements,
that the ratio pB/B can be used to track solar wind features in three
dimensions for scientific and space weather applications better in
the heliosphere than corona, and that,as an independent measurement
of background signal, pB measurements may be used to reduce the effect
of background radiances including the stably polarized zodiacal light.

---------------------------------------------------------
Title: The Thomson Surface. III. Tracking Features in 3D
Authors: Howard, T. A.; Tappin, S. J.; Odstrcil, D.; DeForest, C. E.
2013ApJ...765...45H Altcode:
In this, the final installment in a three-part series on the Thomson
surface, we present simulated observations of coronal mass ejections
(CMEs) observed by a hypothetical polarizing white light heliospheric
imager. Thomson scattering yields a polarization signal that can be
exploited to locate observed features in three dimensions relative
to the Thomson surface. We consider how the appearance of the CME
changes with the direction of trajectory, using simulations of a simple
geometrical shape and also of a more realistic CME generated using
the ENLIL model. We compare the appearance in both unpolarized B and
polarized pB light, and show that there is a quantifiable difference
in the measured brightness of a CME between unpolarized and polarized
observations. We demonstrate a technique for using this difference to
extract the three-dimensional (3D) trajectory of large objects such as
CMEs. We conclude with a discussion on how a polarizing heliospheric
imager could be used to extract 3D trajectory information about CMEs
or other observed features.

---------------------------------------------------------
Title: Energy release in the solar corona from spatially resolved
magnetic braids
Authors: Cirtain, J. W.; Golub, L.; Winebarger, A. R.; de Pontieu,
B.; Kobayashi, K.; Moore, R. L.; Walsh, R. W.; Korreck, K. E.; Weber,
M.; McCauley, P.; Title, A.; Kuzin, S.; Deforest, C. E.
2013Natur.493..501C Altcode:
It is now apparent that there are at least two heating mechanisms
in the Sun's outer atmosphere, or corona. Wave heating may be the
prevalent mechanism in quiet solar periods and may contribute to
heating the corona to 1,500,000 K (refs 1, 2, 3). The active corona
needs additional heating to reach 2,000,000-4,000,000 K this heat
has been theoretically proposed to come from the reconnection and
unravelling of magnetic `braids'. Evidence favouring that process has
been inferred, but has not been generally accepted because observations
are sparse and, in general, the braided magnetic strands that are
thought to have an angular width of about 0.2 arc seconds have not been
resolved. Fine-scale braiding has been seen in the chromosphere but not,
until now, in the corona. Here we report observations, at a resolution
of 0.2 arc seconds, of magnetic braids in a coronal active region that
are reconnecting, relaxing and dissipating sufficient energy to heat
the structures to about 4,000,000 K. Although our 5-minute observations
cannot unambiguously identify the field reconnection and subsequent
relaxation as the dominant heating mechanism throughout active regions,
the energy available from the observed field relaxation in our example
is ample for the observed heating.

---------------------------------------------------------
Title: Imaging the origins of solar wind variability
Authors: DeForest, C.; Howard, T. A.
2012AGUFMSH52A..08D Altcode:
STEREO/SECCHI permits near-continuous imaging of of solar plasma packets
as they form and propagate from the low, middle, and high corona
into the heliosphere. The plasma packets in the solar wind "should"
be visible as they leave the Sun. So why are they hard to view? Partly
because it is difficult to identify the relevant phenomena against the
changing, bright background of the corona itself. We will show recently
produced movies from the COR and HI instruments in the STEREO/SECCHI
suite, using new motion-filtering and background subtraction techniques
that highlight variable features over the fixed and slowly-evolving
streamer belt. These data reveal several potential sources of the solar
wind variability, including packets of departing coronal material,
signs of turbulent instabilities that may break up some streamers,
and possible turbulent mixing in the low heliosphere. We will present
initial results and discuss the course of future work.

---------------------------------------------------------
Title: Loop Evolution Observed with AIA and Hi-C
Authors: Mulu-Moore, F.; Winebarger, A. R.; Cirtain, J. W.; Kobayashi,
K.; Korreck, K. E.; Golub, L.; Kuzin, S.; Walsh, R. W.; DeForest,
C.; De Pontieu, B.; Title, A. M.; Weber, M.
2012AGUFMSH33A2225M Altcode:
In the past decade, the evolution of EUV loops has been used to infer
the loop substructure. With the recent launch of High Resolution Coronal
Imager (Hi-C), this inference can be validated. In this presentation we
discuss the first results of loop analysis comparing AIA and Hi-C data.

---------------------------------------------------------
Title: The Fundamental Structure of Coronal Loops
Authors: Winebarger, A. R.; Warren, H. P.; Cirtain, J. W.; Kobayashi,
K.; Korreck, K. E.; Golub, L.; Kuzin, S.; Walsh, R. W.; DeForest,
C.; De Pontieu, B.; Title, A. M.; Weber, M.
2012AGUFMSH31B..06W Altcode:
During the past ten years, solar physicists have attempted to infer the
coronal heating mechanism by comparing observations of coronal loops
with hydrodynamic model predictions. These comparisons often used
the addition of sub-resolution strands to explain the observed loop
properties. On July 11, 2012, the High Resolution Coronal Imager (Hi-C)
was launched on a sounding rocket. This instrument obtained images of
the solar corona was 0.2-0.3” resolution in a narrowband EUV filter
centered around 193 Angstroms. In this talk, we will compare these
high resolution images to simultaneous density measurements obtained
with the Extreme Ultraviolet Imaging Spectrograph (EIS) on Hinode to
determine whether the structures observed with Hi-C are resolved.

---------------------------------------------------------
Title: Observations of solar eruptions in the heliosphere
Authors: DeForest, C.; Howard, T. A.
2012AGUFMSH54A..01D Altcode:
The STEREO/SECCHI instrument suite now permits quantitative imaging of
heliospheric plasmas. This capability realizes the vision of SECCHI:
complete, quantitative Sun-to-Earth tracking of eruptive events large
and small. Current analyses show that all currently analyzed CMEs
preserve coronal flux structures intact from Sun to Earth, albeit with
distortions that appear inconsistent with symmetric "magnetic cloud"
models; that visible, impulsive flux disconnection events may set the
equilibrium value of the interplanetary magnetic field; that ongoing
force driving results in mass accretion rather than event acceleration;
and that, while some slow solar wind packets appear to erupt from the
corona, others may form in flight. We will present these new results
and report a new project to post-process and make available the entire
SECCHI-A heliospheric data set.

---------------------------------------------------------
Title: Evolution of Coronal Bright Points and Photospheric Magnetic
Fields
Authors: Lamb, D. A.; Saar, S.; DeForest, C.
2012AGUFMSH33A2227L Altcode:
Coronal bright points are excellent probes of the connection between
the photosphere and corona, and occur in sufficiently larger numbers
all over the Sun to make statistical or ensemble studies necessary
and useful. We present initial results on the evolution of coronal
bright points and the state of the associated photospheric magnetic
field. Using an automated bright point detection algorithm that
has found thousands of bright points in multiple SDO/AIA passbands,
combined with an automated magnetic feature tracking algorithm on
SDO/HMI magnetograms, we explore the magnetic conditions necessary
for bright point formation and destruction.

---------------------------------------------------------
Title: Revelations on Heliospheric Imaging of Polarized Light
Authors: Howard, T. A.; DeForest, C.; Tappin, J.; Odstrcil, D.
2012AGUFMSH41B2103H Altcode:
We report on recent developments on the theory of observing the inner
heliosphere with heliospheric imagers. We have extended the theory
of Thomson scattering, which governs the appearance of features
observed by heliospheric imagers, to polarized light observations,
and consider potential benefits to the analysis of features observed
with a polarizing heliospheric imager. We find that when observing
in unpolarized light (as do the current generation of heliospheric
imagers), it is difficult to identify the 3-D location of observed
features because of the broad nature of the scattering function
(causing the Thomson surface to be a Thomson plateau). The broadening
does not occur in polarized light observations, enabling the accurate
3-D location of features to be determined. Our theory is validated by
recent unpolarized light observations from the STEREO/HI-2 heliospheric
imager, and with polarized light simulations of coronal mass ejection
simulations using the ENLIL model.

---------------------------------------------------------
Title: White-light Observations of Solar Wind Transients and
Comparison with Auxiliary Data Sets
Authors: Howard, T. A.; DeForest, C. E.; Reinard, A. A.
2012ApJ...754..102H Altcode:
This paper presents results utilizing a new data processing pipeline
for STEREO/SECCHI. The pipeline is used to identify and track 24 large-
and small-scale solar wind transients from the Sun out to 1 AU. This
comparison was performed during a few weeks around the minimum at
the end of Solar Cycle 23 and the start of Cycle 24 (2008 December
to 2009 January). We use coronagraph data to identify features near
the Sun, track them through HI-2A, and identify their signatures with
in situ data at the Earth and STEREO-B. We provide measurements and
preliminary analysis of the in situ signatures of these features near 1
AU. Along with the demonstration of the utility of heliospheric imagers
for tracking even small-scale structures, we identify and discuss an
important limitation in using geometric triangulation for determining
three-dimensional properties.

---------------------------------------------------------
Title: The Thomson Surface. I. Reality and Myth
Authors: Howard, T. A.; DeForest, C. E.
2012ApJ...752..130H Altcode:
The solar corona and heliosphere are visible via sunlight that is
Thomson-scattered off free electrons and detected by coronagraphs
and heliospheric imagers. It is well known that these instruments are
most responsive to material at the "Thomson surface," the sphere with a
diameter passing through both the observer and the Sun. It is less well
known that in fact the Thomson scattering efficiency is minimized on
the Thomson surface. Unpolarized heliospheric imagers such as STEREO/HI
are thus approximately equally responsive to material over more than
a 90° range of solar exit angles at each given position in the image
plane. We call this range of angles the "Thomson plateau." We observe
that heliospheric imagers are actually more sensitive to material far
from the Thomson surface than close to it, at a fixed radius from
the Sun. We review the theory of Thomson scattering as applied to
heliospheric imaging, feature detection in the presence of background
noise, geometry inference, and feature mass measurement. We show that
feature detection is primarily limited by observing geometry and field
of view, that the highest sensitivity for detection of density features
is to objects close to the observer, that electron surface density
inference is independent of geometry across the Thomson plateau, and
that mass inference varies with observer distance in all geometries. We
demonstrate the sensitivity results with a few examples of features
detected by STEREO, far from the Thomson surface.

---------------------------------------------------------
Title: Quantitative Imaging of the Solar Wind: CME Mass Evolution
and the Interplanetary Magnetic Flux Balance
Authors: DeForest, Craig
2012AAS...22051504D Altcode:
We recently developed post-processing techniques for heliospheric images
from the STEREO spacecraft; the new data sets enable, for the first
time, quantitative photometric studies of evolving wind features at
distances up to 1 A.U. from the Sun. We have used the new data to trace
several CMEs and magnetic disconnection events to their origins in the
solar corona, and to infer the force balance and entrained magnetic flux
in those features. We present recent results showing the relationship
between ICME and CME anatomy, in particular the origin of an observed
interplanetary flux rope and the relationship between original launched
solar material and piled-up sheath material and flux in the storm
at 1. A.U. We discuss implications for understanding space weather
physics and predicting individual events, and point out the importance
of future imaging technologies such as polarized heliospheric imaging.

---------------------------------------------------------
Title: Fix Up Your AIA Images: A Complete Empirically Determined
Set of PSFs And Their Inverses for the AIA EUV Channels
Authors: DeForest, Craig; Poduval, B.; Schmelz, J.
2012AAS...22020704D Altcode:
All EUV imagers to date have had significant stray "light" in the
instrument point-spread function, taking the form of very broad,
low-level wings that disperse low, hard-to-measure amounts of radiance
into pixels far from the core of the PSF -- but whose integrated
intensity is a significant fraction of total received energy. This
results in a hazy appearance to EUV images of the Sun. Thus, to obtain
quantitative results from any EUV imager it is necessary to characterize
the PSF via forward modeling of a distributed object rather than only
(as is done on the ground) with a bright point source. We have
prepared and tested empirical PSF functions for each of the six EUV
channels in the SDO/AIA instrument, and present them here. We have
also prepared inverse PSFs that can be used for simple deconvolution
of stray light from Level 1 AIA data: simply convolve the subject data
with the inverse PSF to improve its stray light characteristics. We present our results and some sample images, together with the
imaging improvements afforded by known-PSF deconvolution. The bottom
line: AIA performs notably better than past instruments but still
requires care when interpreting "diffuse" brightness in the images. We
will demonstrate how deconvolution affects a particular photometric
application: DEM determination of different coronal features.

---------------------------------------------------------
Title: SWAMIS Magnetic Feature Tracking for SDO
Authors: DeForest, Craig; Lamb, D.; Davey, A.; Timmons, R.
2012AAS...22020705D Altcode:
Flux emergence is central to a host of problems in solar dynamics,
from the birth of new active regions and the space weather effects
that result, to the maintenance of quiet sun magnetism at all phases of
the solar cycle. The Southwest Automatic Magnetic Identification Suite
emerging magnetic flux region detection module (SWAMIS-EF) is running
on near-real-time magnetograms from the Helioseismic and Magnetic Imager
on the Solar Dynamics Observatory. This enables near-real-time automated
detection and cataloging of emerging flux regions from the active region
scale down to the scale of the supergranular magnetic network. We will
present an overview of the emerging flux detection algorithm, show some
detailed observations of emerging flux at a variety of spatial scales,
and describe some of the emerging flux region summary quantities
that are output to the Heliophysics Event Knowledgebase. Finally,
we will describe current progress in developing Scientific SWAMIS,
an adaptation and optimization of the SWAMIS tracking algorithm to
run on full disk, full resolution HMI line-of-sight magnetograms.

---------------------------------------------------------
Title: PSF Correction for AIA Using Lunar Limb Data
Authors: DeForest, Craig; Poduval, Bala
2012decs.confE.121D Altcode:
PSF correction is important for myriad inferences that can be made
from EUV imagery, including heating distribution and impulsivity;
DEM; and wave amplitude measurements. Using lunar limb and solar flare
data, we have prepared model PSF functions to describe the scattering
performance of the six EUV channels of AIA. We have not attempted
to model the core of the PSF (focus), only its wings (stray light)
of each channel. We find that, typically, about half of the scattered
light is in the diffuse component of the PSF model, although there is
significant variation across the channels. The diffraction component of
the PSF was determined by direct inspection of the diffraction pattern
from flaring images, with some a priori knowledge of the physics and
nature of the diffraction grid (following the methods of Gburek on
TRACE and more recently, Cheung on AIA); and the diffuse component
was determined by iteratively fitting imaging performance around the
lunar limb in eclipse images, with the assumption that the Moon is
dark in the EUV. We present the PSFs and summary data, along with a
preliminary comparision with the diffraction-only models developed at
SAO, and describe where to get both the quantitative PSF models and
their inverses (for direct deconvolution) in FITS format.

---------------------------------------------------------
Title: Inner Heliospheric Flux Rope Evolution via Imaging of Coronal
Mass Ejections
Authors: Howard, T. A.; DeForest, C. E.
2012ApJ...746...64H Altcode:
Understanding the evolution of flux ropes in coronal mass ejections
(CMEs) is of importance both to the scientific and technological
communities. Scientifically their presence is critical to
models describing CME launch and they likely play a role in
CME evolution. Technologically they are the major contributor to
severe geomagnetic storms. Using a new processing technique on the
STEREO/SECCHI heliospheric imaging data, we have tracked a magnetic
flux rope observed by the Wind spacecraft in December 2008 to its
origins observed by coronagraphs. We thereby establish that the cavity
in the classic three-part coronagraph CME is the feature that becomes
the magnetic cloud. This implies that the bright material ahead of
the cavity is piled-up coronal or solar wind material. We track the
evolution of the cavity en-route and find that its structure transforms
from concave inward (curving away from the Sun) to concave outward
(toward the Sun) around 0.065 AU from the Sun. The pileup was tracked
and its leading edge remained concave inward throughout its journey. Two
other CMEs in January 2009 are also inspected and a similar cavity
is observed in each, suggesting that they too each contained a flux
rope. The results presented here are the first direct observation,
through continuous tracking, associating a particular flux rope observed
in situ with the same flux rope before ejection from the corona. We
speculate that detailed heliospheric imagery of CMEs may lead to a
means by which flux ropes can be identified remotely in the heliosphere.

---------------------------------------------------------
Title: Computer Vision for the Solar Dynamics Observatory (SDO)
Authors: Martens, P. C. H.; Attrill, G. D. R.; Davey, A. R.; Engell,
A.; Farid, S.; Grigis, P. C.; Kasper, J.; Korreck, K.; Saar, S. H.;
Savcheva, A.; Su, Y.; Testa, P.; Wills-Davey, M.; Bernasconi, P. N.;
Raouafi, N. -E.; Delouille, V. A.; Hochedez, J. F.; Cirtain, J. W.;
DeForest, C. E.; Angryk, R. A.; De Moortel, I.; Wiegelmann, T.;
Georgoulis, M. K.; McAteer, R. T. J.; Timmons, R. P.
2012SoPh..275...79M Altcode: 2011SoPh..tmp..144M; 2011SoPh..tmp..213M; 2011SoPh..tmp....8M
In Fall 2008 NASA selected a large international consortium to produce
a comprehensive automated feature-recognition system for the Solar
Dynamics Observatory (SDO). The SDO data that we consider are all of the
Atmospheric Imaging Assembly (AIA) images plus surface magnetic-field
images from the Helioseismic and Magnetic Imager (HMI). We produce
robust, very efficient, professionally coded software modules that
can keep up with the SDO data stream and detect, trace, and analyze
numerous phenomena, including flares, sigmoids, filaments, coronal
dimmings, polarity inversion lines, sunspots, X-ray bright points,
active regions, coronal holes, EIT waves, coronal mass ejections
(CMEs), coronal oscillations, and jets. We also track the emergence and
evolution of magnetic elements down to the smallest detectable features
and will provide at least four full-disk, nonlinear, force-free magnetic
field extrapolations per day. The detection of CMEs and filaments is
accomplished with Solar and Heliospheric Observatory (SOHO)/Large
Angle and Spectrometric Coronagraph (LASCO) and ground-based Hα
data, respectively. A completely new software element is a trainable
feature-detection module based on a generalized image-classification
algorithm. Such a trainable module can be used to find features that
have not yet been discovered (as, for example, sigmoids were in the
pre-Yohkoh era). Our codes will produce entries in the Heliophysics
Events Knowledgebase (HEK) as well as produce complete catalogs for
results that are too numerous for inclusion in the HEK, such as the
X-ray bright-point metadata. This will permit users to locate data on
individual events as well as carry out statistical studies on large
numbers of events, using the interface provided by the Virtual Solar
Observatory. The operations concept for our computer vision system is
that the data will be analyzed in near real time as soon as they arrive
at the SDO Joint Science Operations Center and have undergone basic
processing. This will allow the system to produce timely space-weather
alerts and to guide the selection and production of quicklook images and
movies, in addition to its prime mission of enabling solar science. We
briefly describe the complex and unique data-processing pipeline,
consisting of the hardware and control software required to handle
the SDO data stream and accommodate the computer-vision modules, which
has been set up at the Lockheed-Martin Space Astrophysics Laboratory
(LMSAL), with an identical copy at the Smithsonian Astrophysical
Observatory (SAO).

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Title: Disconnecting Open Solar Magnetic Flux
Authors: DeForest, C. E.; Howard, T. A.; McComas, D. J.
2012ApJ...745...36D Altcode: 2011arXiv1111.7211D
Disconnection of open magnetic flux by reconnection is required to
balance the injection of open flux by coronal mass ejections and
other eruptive events. Making use of recent advances in heliospheric
background subtraction, we have imaged many abrupt disconnection
events. These events produce dense plasma clouds whose distinctive
shape can now be traced from the corona across the inner solar system
via heliospheric imaging. The morphology of each initial event is
characteristic of magnetic reconnection across a current sheet, and
the newly disconnected flux takes the form of a "U-"shaped loop that
moves outward, accreting coronal and solar wind material. We analyzed
one such event on 2008 December 18 as it formed and accelerated at
20 m s-2 to 320 km s-1, thereafter expanding
self-similarly until it exited our field of view 1.2 AU from the
Sun. From acceleration and photometric mass estimates we derive the
coronal magnetic field strength to be 8 μT, 6 R ⊙ above
the photosphere, and the entrained flux to be 1.6 × 1011
Wb (1.6 × 1019 Mx). We model the feature's propagation by
balancing inferred magnetic tension force against accretion drag. This
model is consistent with the feature's behavior and accepted
solar wind parameters. By counting events over a 36 day window,
we estimate a global event rate of 1 day-1 and a global
solar minimum unsigned flux disconnection rate of 6 × 1013
Wb yr-1 (6 × 1021 Mx yr-1) by this
mechanism. That rate corresponds to ~ - 0.2 nT yr-1 change
in the radial heliospheric field at 1 AU, indicating that the mechanism
is important to the heliospheric flux balance.

---------------------------------------------------------
Title: Flux Ropes and Small-Scale Interplanetary Transients - New
Revelations from STEREO/SECCHI
Authors: Howard, T. A.; DeForest, C. E.; Reinard, A. A.; Tappin, S. J.
2011AGUFMSH23C1966H Altcode:
We present scientific results using a new processing pipeline from
the SECCHI instrument suite on STEREO-A. This pipeline reduces stellar
and F coronal noise to an unprecedented level to where very small and
faint solar wind transients can be observed and tracked. This allows
the accomplishment of new revelations about small-scale transients and
about the anatomy of coronal mass ejections (CMEs) en-route through the
inner heliosphere. Our results are from the time period corresponding
to the lowest part of the deep minimum of Solar Cycle 23-24 (December
2009 - January 2009) and find a dynamic solar wind even when at its
quietest. We identify solar wind puffs and blobs, likely disconnection
events, and a number of CMEs, and we track them through the SECCHI
suite to distances out to and beyond 1 AU. We are therefore able to
unambiguously identify each of their signatures upon their arrival
at in-situ spacecraft. For the CMEs we track magnetic flux ropes
(called magnetic clouds) back to their coronagraph origins and identify
them as the cavity component of the so-called classic three-part CME
structure. Finally we track the evolution of the structure of the flux
ropes through the heliosphere, and find significant distortion.

---------------------------------------------------------
Title: Investigations to Determine the Origin of the Solar Wind with
the SPICE EUV Imaging Spectrograph and the Solar Orbiter Mission
Authors: Hassler, D. M.; Deforest, C.; Spice Team
2011AGUFMSH33B2054H Altcode:
At large spatial scales, the structure of the solar wind and it's
mapping back to the solar corona, is thought to be reasonably well
understood. However, the detailed structure of the various source
regions at chromospheric and transition region heights is extremely
complex, and less well understood. Determining this connection between
heliospheric structures and their source regions at the Sun is one
of the overarching objective of the Solar Orbiter mission. During
perihelion segments of its orbit, when the spacecraft is in
quasi-corotation with the Sun, Solar Orbiter will determine the plasma
parameters and compositional signatures of the solar wind, which can be
compared directly with the spectroscopic signatures of coronal ions with
differing charge-to-mass ratios and FIP. One of the key instruments on
the Solar Orbiter mission to make these remote sensing measurements
is the SPICE (Spectral Imaging of the Coronal Environment) imaging
spectrograph. SPICE will provide the images and plasma diagnostics
needed to characterize the plasma state in different source regions,
from active regions to quiet Sun to coronal holes. By comparing
composition, plasma parameters, and low/high FIP ratios of structures
remotely, with those measured directly at the Solar Orbiter spacecraft,
Solar Orbiter will provide the first direct link between solar wind
structures and their source regions at the Sun. This talk will provide
a background of previous compositional correlation measurements and
an outline of the method to be used for comparing the spectroscopic
and in-situ plasma parameters to be measured with Solar Orbiter.

---------------------------------------------------------
Title: Imaging the Turbulent Solar Wind with STEREO/SECCHI
Authors: DeForest, C.; Howard, T. A.; Matthaeus, W. H.
2011AGUFMSH44B..02D Altcode:
Newly processed data from STEREO/SECCHI offer a glimpse into the
development of turbulence in the heliospheric current sheet and the
slow solar wind. Careful background subtraction yields photometrically
calibrated images of "moving feature excess density" throughout the
inner heliosphere near the plane of the ecliptic. We report on initial
work extracting the structure function of dense features via remote
sensing of the Thomson scattered sunlight from free electron clouds
in the inner heliosphere. Precise imaging results of this type show
promise in enabling extraction of quantitative information about
interplanetary turbulence from direct imaging.

---------------------------------------------------------
Title: Observations of Emerging Flux Regions with SWAMIS-EF
Authors: Lamb, Derek A.; DeForest, Craig E.; Davey, Alisdair R.;
Timmons, Ryan P.
2011sdmi.confE..59L Altcode:
The SWAMIS magnetic feature tracking algorithm is working in the
SDO pipeline to detect emerging flux regions from the size of active
regions down to ephemeral regions. We will present a brief overview
of the emerging flux detection algorithm, show a sample of events as
one would see them in the HEK, and show some examples illustrating
the underlying performance of the algorithm in more detail than is
available in the HEK. Finally, we will present some measurements of
the amount of magnetic flux emergence detected by the algorithm over
a month-long time period and compare that with previously-published
estimates of the magnetic flux emergence rate. SWAMIS-EF enables such
previously-difficult measurements to now be routinely made.

---------------------------------------------------------
Title: Observations of Detailed Structure in the Solar Wind at 1 AU
with STEREO/HI-2
Authors: DeForest, C. E.; Howard, T. A.; Tappin, S. J.
2011ApJ...738..103D Altcode: 2011arXiv1104.1615D
We present images of solar wind electron density structures at
distances of 1 AU, extracted from the STEREO/HI-2 data. Collecting
the images requires separating the Thomson-scattered signal from the
other background/foreground sources that are 103 times
brighter. Using a combination of techniques, we are able to generate
calibrated imaging data of the solar wind with sensitivity of a few ×
10-17 B sun, compared to the background signal of
a few × 10-13 B sun, using only the STEREO/HI-2
Level 1 data as input. These images reveal detailed spatial structure
in coronal mass ejections (CMEs) and the solar wind at projected solar
distances in excess of 1 AU, at the instrumental motion-blur resolution
limit of 1°-3°. CME features visible in the newly reprocessed
data from 2008 December include leading-edge pileup, interior voids,
filamentary structure, and rear cusps. "Quiet" solar wind features
include V-shaped structures centered on the heliospheric current sheet,
plasmoids, and "puffs" that correspond to the density fluctuations
observed in situ. We compare many of these structures with in situ
features detected near 1 AU. The reprocessed data demonstrate that it
is possible to perform detailed structural analyses of heliospheric
features with visible light imagery, at distances from the Sun of at
least 1 AU.

---------------------------------------------------------
Title: Fluxon Simulations of Magnetic Reconnection at Coronal Hole
Boundaries
Authors: Lamb, Derek Allen; DeForest, Craig E.
2011shin.confE.172L Altcode:
Because the equatorial extensions of polar coronal holes rotate
more rigidly than the underlying photosphere, they have long
been assumed to have substantial magnetic reconnection at their
boundaries. However, evidence for this reconnection has been sparse
until very recently. We assume that reconnection facilitated by the
evolving small-scale magnetic fields can drive at least some of the
coronal hole boundary evolution. We hypothesize that a bias in the
direction of that reconnection, perhaps imposed by the faster rotation
of the upper corona, is sufficient to give equatorial coronal holes
their rigid rotation. We present some preliminary simulations using
FLUX, a reconnection-controlled coronal MHD simulation framework,
of the reconnection at coronal hole - quiet sun boundaries.

---------------------------------------------------------
Title: Small-Scale Magnetic Reconnection at Equatorial Coronal
Hole Boundaries
Authors: Lamb, Derek; DeForest, C. E.
2011SPD....42.1832L Altcode: 2011BAAS..43S.1832L
Coronal holes have long been known to be the source of the fast solar
wind at both high and low latitudes. The equatorial extensions of
polar coronal holes have long been assumed to have substantial magnetic
reconnection at their boundaries, because they rotate more rigidly than
the underlying photosphere. However, evidence for this reconnection
has been sparse until very recently. We present some evidence that
reconnection due to the evolution of small-scale magnetic fields may
be sufficient to drive coronal hole boundary evolution. We hypothesize
that a bias in the direction of that reconnection is sufficient to give
equatorial coronal holes their rigid rotation. We discuss the prospects
for investigating this using FLUX, a reconnection-controlled coronal MHD
simulation framework. This work was funded by the NASA SHP-GI program.

---------------------------------------------------------
Title: Imaging The Solar Wind At 1 AU. With Stereo/hi-2
Authors: DeForest, Craig; Howard, T.; Tappin, J.
2011SPD....42.1402D Altcode: 2011BAAS..43S.1402D
The STEREO/HI-2 wide-field imagers have demonstrated the importance
of heliospheric imaging to understanding CMEs and the solar wind,
but the difficulty of background subtraction has precluded full
exploitation of this rich resource: current results are based mainly on
morphological studies of running difference movies and time-elongation
"J-plots". With a combination of several commonly used image processing
techniques, we have developed a pipeline to extract quantitative
wind imagery from HI-2 at elongation angles as high as 70 degrees
from the Sun and brightness ranges 3-4 orders of magnitude fainter
than the background. The processed data reveal to direct view
a surprising menagerie of features in the solar wind: voids within
CMEs, remnant loop structures, disconnected plasmoids, current sheets,
interacting streams, and compressive wave fronts. Despite motion blur
of 1-3 degrees in the HI-2 instrument, in some cases the images are
clear enough to reveal striated "tracer” structures that appear
to follow the magnetic field, just as in the solar corona. We will
briefly summarize the reduction pipeline, demonstrate its output
with spectacular movies of Earth-directed events and "quiet Sun",
and present preliminary results from examination of the quantitative
data. This work was supported in major part by NASA's SHP-GI program.

---------------------------------------------------------
Title: Investigations to Determine the Origin of the Solar Wind with
SPICE and SolarOrbiter
Authors: Hassler, Donald M.; DeForest, C.; Wilkinson, E.; Davila,
J.; SPICE Team
2011SPD....42.2402H Altcode: 2011BAAS..43S.2402H
At large spatial scales, the structure of the solar wind and it's
mapping back to the solar corona, is thought to be reasonably well
understood. However, the detailed structure of the various source
regions at chromospheric and transition region heights is extremely
complex, and less well understood. Determining this connection
between heliospheric structures and their source regions at the Sun
is one of the overarching objective of the Solar Orbiter mission. During perihelion segments of its orbit, when the spacecraft is
in quasi-corotation with the Sun, Solar Orbiter will determine the
plasma parameters and compositional signatures of the solar wind,
which can be compared directly with the spectroscopic signatures of
coronal ions with differing charge-to-mass ratios and FIP. One of the
key instruments on the Solar Orbiter mission to make these remote
sensing measurements is the SPICE (Spectral Imaging of the Coronal
Environment) imaging spectrograph. SPICE will provide the images and
plasma diagnostics needed to characterize the plasma state in different
source regions, from active regions to quiet Sun to coronal holes. By
comparing composition, plasma parameters, and low/high FIP ratios of
structures remotely, with those measured directly at the Solar Orbiter
spacecraft, Solar Orbiter will provide the first direct link between
solar wind structures and their source regions at the Sun. This
talk will provide a background of previous compositional correlation
measurements and an outline of the method to be used for comparing
the spectroscopic and in-situ plasma parameters to be measured with
Solar Orbiter.

---------------------------------------------------------
Title: Solar Orbiter Core Science With the SPICE Spectral Imager
Authors: DeForest, Craig; Hassler, D.; Wilkinson, E.; SPICE Science
Team
2011SPD....42.1503D Altcode: 2011BAAS..43S.1503D
SPICE is a novel spectral imager designed for deployment on Solar
Orbiter, and directly addresses the core science using high level
science data products including Dopplergrams, "FIPograms" and "QMograms"
to correlate solar wind source regions at the surface of the Sun with
in situ measurements made simultaneously on board Solar Orbiter. SPICE data are critical to the key motivating questions for the
Solar Orbiter mission, and the data products and observing plans draw
heavily from lessons learned in the SOHO mission to yield accessible
data products that can be compared easily with other types of solar
data. We describe key questions that Solar Orbiter will address,
and how SPICE data products enable answering them.

---------------------------------------------------------
Title: The Evolution Of Coronal Mass Ejections And Large Solar
Wind Structures
Authors: Howard, Tim A.; DeForest, C. E.; Reinard, A. A.
2011SPD....42.1308H Altcode: 2011BAAS..43S.1308H
Processing of STEREO/HI-2 heliospheric image data has reached a level
where extremely faint structures can be tracked through their entire
trajectory to 1 AU. This enables detailed comparison with auxiliary
datasets allowing an unambiguous identification of solar wind transient
structures from the Sun to 1 AU and beyond. These transients are
in the scale range from large CMEs to "puffs" only a few hundred Mm
across. For events that impact in-situ spacecraft, we are able to make
quantitative measurements of these transients without the confusion
involving the identification of heliospheric image features. We present
results utilizing a new processing pipeline of HI-2 data developed by
DeForest et al. (2011) that link transient features observed by white
light coronagraphs with in-situ datasets near 1 AU. The results include
attempts of three-dimensional reconstruction, trajectory and kinematic
evolution of these features, along with a detailed in-situ analysis
of the magnetic field and plasma comprising each of the features.

---------------------------------------------------------
Title: Preliminary PSF Inversion for SDO/AIA Lunar Occutation Data
Authors: DeForest, Craig; Poduval, B.
2011SPD....42.2127D Altcode: 2011BAAS..43S.2127D
We present initial results from PSF inversion of the AIA eclipse data
from fall 2010. Initial stray light estimates for the 171 band are
favorable compared to TRACE, and comparable to STEREO/EUVI.

---------------------------------------------------------
Title: A Microsatellite Heliospheric Imaging Network for Science
and Space Weather
Authors: Deforest, C. E.; Howard, T. A.; Kief, C.; Chime Mission
Development Team
2010AGUFMSH41A1779D Altcode:
Heliospheric imaging has been shown to yield new insight into
ICME physics, and to improve greatly space weather prediction at
Earth. However, all existing heliospheric imagers are either well past
prime mission (SMEI) or soon to be unable to view near-Earth space
(STEREO/HI). We present a novel approach to heliospheric imaging,
using a constellation of microsatellites in Sun-synchronous LEO. Recent
developments in component miniaturization and standardization allow
very inexpensive, very small spacecraft, dominated by an optical baffle
in the 30cm size range, to image propagating features in the solar
wind. Such spacecraft can be produced and deployed as a constellation
to improve imaging cadence and reveal new physics of Earthbound CMEs
and other solar wind features. Further, using a constellation improves
reliability into the operational class (mean time between failures
well over 100 years for the network as a whole), for a fraction
of the cost of a single traditional operational-class instrument
that can monitor ICMEs to predict space weather. Other advantages
conferred by using low-cost LEO microsatellites outweigh challenges
of designing to the small form factor. Sensitivity analysis shows
that such a microsatellite constellation will enable new scientific
measurements relevant to ICME evolution, shock formation, and solar
wind propagation that are inaccessible from existing heliospheric
imagers and conventional instrument designs, answering fundamental
questions about how solar effects interact with the heliosphere.

---------------------------------------------------------
Title: Finding Magnetic Features and Emerging Flux Regions in HMI
Data with SWAMIS
Authors: Lamb, D. A.; Deforest, C.
2010AGUFMSH22A..06L Altcode:
We present an adaptation of the Southwest Automatic Magnetic
Identification Suite (SWAMIS) feature tracking algorithm for use in
the SDO-HMI pipeline. Feature tracking algorithms have been used
by several groups to identify features in what are now relatively
small magnetogram datasets. They have been used across a large range
of scales, from active regions to the smallest features visible with
Hinode SOT. SWAMIS is being incorporated into the SDO-HMI pipeline in
two forms: to identify large flux emergence regions, and to track every
feature seen by HMI. This will enable real-time detection of events of
interest to space weather forecasters, as well as large statistical
studies of HMI data. We will describe the status of this code in the
HMI pipeline and provide some examples of its use. A stand-alone version
of the software for use on fixed-size datasets is also available.

---------------------------------------------------------
Title: Solar Magnetic Tracking. III. Apparent Unipolar Flux Emergence
in High-resolution Observations
Authors: Lamb, D. A.; DeForest, C. E.; Hagenaar, H. J.; Parnell,
C. E.; Welsch, B. T.
2010ApJ...720.1405L Altcode:
Understanding the behavior of weak magnetic fields near the detection
limit of current instrumentation is important for determining the
flux budget of the solar photosphere at small spatial scales. Using
0farcs3-resolution magnetograms from the Solar Optical Telescope's
Narrowband Filter Imager (NFI) on the Hinode spacecraft, we confirm
that the previously reported apparent unipolar magnetic flux emergence
seen in intermediate-resolution magnetograms is indeed the coalescence
of previously existing flux. We demonstrate that similar but smaller
events seen in NFI magnetograms are also likely to correspond to
the coalescence of previously existing weak fields. The uncoalesced
flux, detectable only in the ensemble average of hundreds of these
events, accounts for 50% of the total flux within 3 Mm of the detected
features. The spatial scale at which apparent unipolar emergence can
be directly observed as coalescence remains unknown. The polarity of
the coalescing flux is more balanced than would be expected given the
imbalance of the data set, however without further study we cannot
speculate whether this implies that the flux in the apparent unipolar
emergence events is produced by a granulation-scale dynamo or is
recycled from existing field.

---------------------------------------------------------
Title: Symmetric Coronal Jets: A Reconnection-controlled Study
Authors: Rachmeler, L. A.; Pariat, E.; DeForest, C. E.; Antiochos,
S.; Török, T.
2010ApJ...715.1556R Altcode:
Current models and observations imply that reconnection is a key
mechanism for destabilization and initiation of coronal jets. We evolve
a system described by the theoretical symmetric jet formation model
using two different numerical codes with the goal of studying the
role of reconnection in this system. One of the codes is the Eulerian
adaptive mesh code ARMS, which simulates magnetic reconnection through
numerical diffusion. The quasi-Lagrangian FLUX code, on the other hand,
is ideal and able to evolve the system without reconnection. The ideal
nature of FLUX allows us to provide a control case of evolution without
reconnection. We find that during the initial symmetric and ideal phase
of evolution, both codes produce very similar morphologies and energy
growth. The symmetry is then broken by a kink-like motion of the axis
of rotation, after which the two systems diverge. In ARMS, current
sheets formed and reconnection rapidly released the stored magnetic
energy. In FLUX, the closed field remained approximately constant
in height while expanding in width and did not release any magnetic
energy. We find that the symmetry threshold is an ideal property of the
system, but the lack of energy release implies that the observed kink is
not an instability. Because of the confined nature of the FLUX system,
we conclude that reconnection is indeed necessary for jet formation
in symmetric jet models in a uniform coronal background field.

---------------------------------------------------------
Title: Hinode Solar Optical Telescope Observations of the Source
Regions and Evolution of "Type II" Spicules at the Solar Polar Limb
Authors: Sterling, Alphonse C.; Moore, Ronald L.; DeForest, Craig E.
2010ApJ...714L...1S Altcode:
We examine solar spicules using high-cadence Ca II data of the north
pole coronal hole region, using the Solar Optical Telescope (SOT)
on the Hinode spacecraft. The features we observe are referred to as
"Type II" spicules by De Pontieu et al. in 2007. By convolving the
images with the inverse-point-spread function for the SOT Ca II filter,
we are able to investigate the roots of some spicules on the solar
disk, and the evolution of some spicules after they are ejected from
the solar surface. We find that the source regions of at least some of
the spicules correspond to locations of apparent-fast-moving (~few ×
10 km s-1), transient (few 100 s), Ca II brightenings on the
disk. Frequently the spicules occur when these brightenings appear to
collide and disappear. After ejection, when seen above the limb, many
of the spicules fade by expanding laterally (i.e., roughly transverse
to their motion away from the solar surface), splitting into two or
more spicule "strands," and the spicules then fade without showing
any downward motion. Photospheric/chromospheric acoustic shocks alone
likely cannot explain the high velocities (~100 km s-1) of
the spicules. If the Ca II brightenings represent magnetic elements,
then reconnection among those elements may be a candidate to explain
the spicules. Alternatively, many of the spicules could be small-scale
magnetic eruptions, analogous to coronal mass ejections, and the
apparent fast motions of the Ca II brightenings could be analogs of
flare loops heated by magnetic reconnection in these eruptions.

---------------------------------------------------------
Title: Computer Vision for SDO: First Results from the SDO Feature
Finding Algorithms
Authors: Martens, Petrus C.; Attrill, G.; Davey, A.; Engell, A.;
Farid, S.; Grigis, P.; Kasper, J.; Korreck, K.; Saar, S.; Su, Y.;
Testa, P.; Wills-Davey, M.; Bernasconi, P.; Raouafi, N.; Georgoulis,
M.; Deforest, C.; Peterson, J.; Berghoff, T.; Delouille, V.; Hochedez,
J.; Mampaey, B.; Verbeek, C.; Cirtain, J.; Green, S.; Timmons, R.;
Savcheva, A.; Angryk, R.; Wiegelmann, T.; McAteer, R.
2010AAS...21630804M Altcode:
The SDO Feature Finding Team produces robust and very efficient
software modules that can keep up with the relentless SDO data stream,
and detect, trace, and analyze a large number of phenomena including:
flares, sigmoids, filaments, coronal dimmings, polarity inversion
lines, sunspots, X-ray bright points, active regions, coronal holes,
EIT waves, CME's, coronal oscillations, and jets. In addition we track
the emergence and evolution of magnetic elements down to the smallest
features that are detectable, and we will also provide at least four
full disk nonlinear force-free magnetic field extrapolations per day. During SDO commissioning we will install in the near-real time data
pipeline the modules that provide alerts for flares, coronal dimmings,
and emerging flux, as well as those that trace filaments, sigmoids,
polarity inversion lines, and active regions. We will demonstrate
the performance of these modules and illustrate their use for science
investigations.

---------------------------------------------------------
Title: Emerging Flux Detection for the Solar Dynamics Observatory
Authors: DeForest, Craig; Peterson, J.
2010AAS...21640209D Altcode: 2010BAAS...41..874D
We present an emerging-flux detection method and code that are being
incorporated into the early warning pipeline for the Solar Dynamics
Observatory. SWAMIS is a magnetic feature tracking code that has
been used primarily to probe the small scale solar dynamo; we have
adapted it to find large scale bipolar emergences of new flux in time
series of HMI full-disk line of sight magnetograms. The new code,
SWAMIS-EF, performs feature identification and tracking on multiple
spatial scales to identify large flux emergence events that, at full
instrument resolution, segment into large clusters of small feature
motions. SWAMIS-EF generates flux-emergence event records that highlight
all large scale flux emergences (&gt;10 EMx of magnetic flux) in the
favorable portion of the solar disk (nominally, within 0.86 Rs of disk
center). A variant on the code, "SWAMIS-S", will describe the motion
and interactions of every single resolvable magnetic feature on the
Sun, and is anticipated by the end of Mission Year 1. The SWAMIS-EF
event stream will enable both improved space weather prediction and
retrospective "data mining" studies of the solar dynamo and the effect
of flux emergence on the chromosphere and corona.

---------------------------------------------------------
Title: Solar Polar Spicules Observed with Hinode
Authors: Sterling, Alphonse C.; Moore, R. L.; DeForest, C. E.
2010AAS...21640303S Altcode: 2010BAAS...41Q.878S
We examine solar polar region spicules using high-cadence Ca II data
from the Solar Optical Telescope (SOT) on the Hinode spacecraft. We
sharpened the images by convolving them with the inverse-point-spread
function of the SOT Ca II filter, and we are able to see some of
the spicules originating on the disk just inside the limb. Bright
points are frequently at the root of the disk spicules. These “Ca
II brightenings” scuttle around at few x 10 km/s, live for 100 sec,
and may be what are variously known as “H2V grains,”
“K2V grains,” or "K2V bright points.” When
viewed extending over the limb, some of the spicules appear to expand
horizontally or spit into two or more components, with the horizontal
expansion or splitting velocities reaching 50 km/s. This work was
funded by NASA's Science Mission Directorate through the Living
With a Star Targeted Research and Technology Program, the Supporting
Research and Program, the Heliospheric Guest Investigator Program,
and the Hinode project.

---------------------------------------------------------
Title: The Cubesat Heliospheric Imaging Experiment for Space Weather
Prediction
Authors: DeForest, Craig; Howard, T.; Dickinson, J.; Epperly, M.;
Kief, C.
2010AAS...21640702D Altcode: 2010BAAS...41..859D
Heliospheric imaging data have been shown to improve space weather
prediction by an order of magnitude, and heliospheric monitoring
by the SMEI and STEREO-HI instruments have proven to be extremely
useful for understanding heliospheric conditions near Earth. However,
SMEI is approaching end-of-life and the STEREOs are drifting away from
favorable Earth-viewing geometry just as the new solar cycle begins. CHIME is an innovative, miniaturized, fully functional space weather
heliospheric monitor that fits within the 3U CubeSat envelope and
can be flown individually (as a scientific or demonstrator mission)
or in a swarm (to attain operational-class reliability) at a small
fraction of the cost of a conventional mission. Here we describe
the CHIME concept and its use with the automated processing pipeline
AICMED to improve space weather prediction.

---------------------------------------------------------
Title: Scientific Revelations Using Heliospheric Imager Observations
of Coronal Mass Ejections
Authors: Howard, Timothy A.; DeForest, C.; Tappin, J.
2010AAS...21640616H Altcode: 2010BAAS...41..882H
The recent emergence of heliospheric imagers (SMEI (2003), HI
(2006)) has enabled for the first time the tracking of coronal mass
ejections (CMEs) constantly across large distances, to 1 AU and
beyond. This allows not only a study of the evolutionary nature
of CMEs through the inner heliosphere, but also the extraction of
additional three-dimensional (3-D) information that is not available
in coronagraphs. This is because the linearity imposed on white light
coronagraph images breaks down across large distances, allowing, with
careful analysis of geometry and Thomson scattering, the extraction of
3-D structural and kinematic properties of CMEs. Additional scientific
information is therefore available through heliospheric imagers. We
present scientific results using such analysis on an Earth-directed
event observed in November 2007. Our 3-D reconstruction analysis
reveals that the event is a combination of a CME with a corotating
interaction region (CIR), and we offer suggestions as to how this
combined structure arose.

---------------------------------------------------------
Title: Solar Observing from Next-Generation Suborbital Platforms
Authors: Deforest, C.
2010LPICo1534...25D Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Automated Feature and Event Detection with SDO AIA and HMI Data
Authors: Davey, Alisdair; Martens, P. C. H.; Attrill, G. D. R.;
Engell, A.; Farid, S.; Grigis, P. C.; Kasper, J.; Korreck, K.; Saar,
S. H.; Su, Y.; Testa, P.; Wills-Davey, M.; Savcheva, A.; Bernasconi,
P. N.; Raouafi, N. -E.; Delouille, V. A.; Hochedez, J. F. .; Cirtain,
J. W.; Deforest, C. E.; Angryk, R. A.; de Moortel, I.; Wiegelmann,
T.; Georgouli, M. K.; McAteer, R. T. J.; Hurlburt, N.; Timmons, R.
2010cosp...38.2878D Altcode: 2010cosp.meet.2878D
The Solar Dynamics Observatory (SDO) represents a new frontier in
quantity and quality of solar data. At about 1.5 TB/day, the data will
not be easily digestible by solar physicists using the same methods
that have been employed for images from previous missions. In order for
solar scientists to use the SDO data effectively they need meta-data
that will allow them to identify and retrieve data sets that address
their particular science questions. We are building a comprehensive
computer vision pipeline for SDO, abstracting complete metadata
on many of the features and events detectable on the Sun without
human intervention. Our project unites more than a dozen individual,
existing codes into a systematic tool that can be used by the entire
solar community. The feature finding codes will run as part of the SDO
Event Detection System (EDS) at the Joint Science Operations Center
(JSOC; joint between Stanford and LMSAL). The metadata produced will
be stored in the Heliophysics Event Knowledgebase (HEK), which will be
accessible on-line for the rest of the world directly or via the Virtual
Solar Observatory (VSO) . Solar scientists will be able to use the
HEK to select event and feature data to download for science studies.

---------------------------------------------------------
Title: The Density of Coronal Null Points from Hinode and MDI
Authors: Longcope, D.; Parnell, C.; DeForest, C.
2009ASPC..415..178L Altcode: 2009arXiv0901.0865L
Magnetic null points can be located numerically in a potential field
extrapolation or their average density can be estimated from the
Fourier spectrum of a magnetogram. We use both methods to compute the
null point density from a quiet Sun magnetogram made with Hinode's NFI
and from magnetograms from SOHO's MDI in both its high-resolution and
low-resolution modes. All estimates of the super-chromospheric column
density (z&gt;1.5 Mm) agree with one another and with the previous
measurements: 3×10-3 null points per square Mm of solar
surface.

---------------------------------------------------------
Title: First Light with SHAZAM (the Stereoscopic High-speed Zeeman
Magnetograph)
Authors: Deforest, C. E.; Peterson, J.
2009AGUFMSH51A1265D Altcode:
The Stereoscopic High-speed Zeeman Magnetograph (SHAZAM) is
a visible-light solar magnetograph that is designed to deliver
quantitative magnetograms as fast as possible. It uses the principle
of "stereoscopic spectroscopy" to extract Zeeman splitting information
throughout a 2-D focal plane, from a single six-beam exposure. SHAZAM is
capable of operating at or close to the diffraction limit of its host
telescope, with exposure times short enough to beat atmospheric seeing
and a cadence of 8-10 Hz, fast enough for speckle reconstruction of
near-diffraction-limited images. SHAZAM has been deployed at the NSO's
Dunn Solar Telescope and is intended to deploy at the 1.0m Swedish
Solar Telescope on La Palma and/or the new 1.6m telescope at the Big
Bear Solar Observatory. It prototypes a high-speed instrument intended
for installation at the planned ATST facility on Maui. We present the
motivation, principle of operation, and first-light results from the
first six-beam SHAZAM run at the DST in May of 2009.

---------------------------------------------------------
Title: Fluxon modeling of breakout CMEs
Authors: Rachmeler, L. A.; Deforest, C. E.; DeVore, C. R.; Antiochos,
S. K.
2009AGUFMSH41B1675R Altcode:
The pivotal element of the classic breakout model of CME initiation
is reconnection that occurs above inner magnetic field sheared by
rotation. We research this model with the FLUX code both with and
without reconnection. Without reconnection an eruption occurs after
several turns have been injected into the active region. The resultant
expansion or eruption is more like a kink-unstable flux rope than a
classic breakout CME. By varying whether and where reconnection is
allowed, we determine the location of magnetic free energy release in
the breakout model.

---------------------------------------------------------
Title: Fluxon modeling of breakout CMEs
Authors: Rachmeler, Laurel A.; DeForest, C. E.
2009shin.confE..16R Altcode:
The pivotal element of the classic quadrupolar breakout model of
CME initiation is reconnection that occurs above inner magnetic field
sheared by rotation. We research this model with the FLUX code both with
and without reconnection. Without reconnection an eruption occurs after
several turns have been injected into the active region. The resultant
slow expansion or eruption is more like a kink-unstable flux rope than
a classic breakout CME. We expect that a global reconnection threshold
within FLUX will produce a more classic breakout evolution with initial
reconnection occurring across the null just above the sheared field. By
varying whether and where reconnection is allowed, we determine the
location of magnetic free energy release in the breakout model.

---------------------------------------------------------
Title: A Power-Law Distribution of Solar Magnetic Fields Over More
Than Five Decades in Flux
Authors: Parnell, C. E.; DeForest, C. E.; Hagenaar, H. J.; Johnston,
B. A.; Lamb, D. A.; Welsch, B. T.
2009ApJ...698...75P Altcode:
Solar flares, coronal mass ejections, and indeed phenomena on all
scales observed on the Sun, are inextricably linked with the Sun's
magnetic field. The solar surface is covered with magnetic features
observed on many spatial scales, which evolve on differing timescales:
the largest features, sunspots, follow an 11-year cycle; the smallest
seem to follow no cycle. Here, we analyze magnetograms from Solar and
Heliospheric Observatory (SOHO)/Michelson Doppler Imager (full disk
and high resolution) and Hinode/Solar Optical Telescope to determine
the fluxes of all currently observable surface magnetic features. We
show that by using a "clumping" algorithm, which counts a single
"flux massif" as one feature, all feature fluxes, regardless of flux
strength, follow the same distribution—a power law with slope -1.85
± 0.14—between 2 × 1017 and 1023 Mx. A power
law suggests that the mechanisms creating surface magnetic features
are scale-free. This implies that either all surface magnetic features
are generated by the same mechanism, or that they are dominated by
surface processes (such as fragmentation, coalescence, and cancellation)
in a way which leads to a scale-free distribution.

---------------------------------------------------------
Title: Computer Vision for The Solar Dynamics Observatory
Authors: Martens, Petrus C.; Angryk, R. A.; Bernasconi, P. N.; Cirtain,
J. W.; Davey, A. R.; DeForest, C. E.; Delouille, V. A.; De Moortel,
I.; Georgoulis, M. K.; Grigis, P. C.; Hochedez, J. E.; Kasper, J.;
Korreck, K. E.; Reeves, K. K.; Saar, S. H.; Savcheva, A.; Su, Y.;
Testa, P.; Wiegelmann, T.; Wills-Davey, M.
2009SPD....40.1711M Altcode:
NASA funded a large international consortium last year to produce
a comprehensive system for automated feature recognition in SDO
images. The data we consider are all AIA and EVE data plus surface
magnetic field images from HMI. Helioseismology is addressed by another
group. We will produce robust and very efficient software modules
that can keep up with the relentless SDO data stream and detect, trace,
and analyze a large number of phenomena, including: flares, sigmoids,
filaments, coronal dimmings, polarity inversion lines, sunspots,
X-ray bright points, active regions, coronal holes, EIT waves, CME's,
coronal oscillations, and jets. In addition we will track the emergence
and evolution of magnetic elements down to the smallest features
that are detectable, and we will also provide at least four full
disk nonlinear force-free magnetic field extrapolations per day. A completely new software element that rounds out this suite is a
trainable feature detection module, which employs a generalized image
classification algorithm to produce the texture features of the images
analyzed. A user can introduce a number of examples of the phenomenon
looked and the software will return images with similar features. We
have tested a proto-type on TRACE data, and were able to "train" the
algorithm to detect sunspots, active regions, and loops. Such a module
can be used to find features that have not even been discovered yet,
as, for example, sigmoids were in the pre-Yohkoh era. Our codes
will produce entries in the Helio Events Knowledge base, and that will
permit users to locate data on individual events as well as carry out
statistical studies on large numbers of events, using the interface
provided by the Virtual Solar Observatory.

---------------------------------------------------------
Title: First Results from a Novel Magnetograph (SHAZAM)
Authors: DeForest, Craig; Rimmele, T.; Berger, T.; Peterson, J.
2009SPD....40.3301D Altcode:
The magnetic energy flux through the Sun's surface is dominated by small
features at all currently observable spatial scales; hence there is a
strong need to improve the spatial resolution of magnetic measurements,
which are increasingly photon starved as telescopes improve. The Solar
High-speed Zeeman Magnetograph (SHAZAM) is a line-of-sight magnetograph
based on the principle of spectral stereoscopy. It is designed to
acquire magnetograms quickly enough to beat image fluctuations due
to both solar evolution and terrestrial seeing, even on scales under
100 km on the Sun. It is over 100x more photon efficient than existing
quantitative magnetographs such as SOHO/MDI. We present first results
from an observing run at the National Solar Observatory's Dunn Solar
Telescope in May 2009, hopefully including near-diffraction-limited,
time resolved magnetogram sequences with better than 150km resolution
on the surface of the Sun.

---------------------------------------------------------
Title: Quadrupolar CME Initiation with Flux
Authors: Rachmeler, Laurel; DeForest, C. E.
2009SPD....40.3706R Altcode:
We present initial results of reconnectionless fluxon simulations of
a full sun quadrupolar system for CME initiation. This research sets a
baseline control case for studying the specific effects of reconnection
in the the breakout reconnection CME model. We are studying this
system with no reconnection, with a globally determined resistivity,
and with targeted reconnection below and above the inner sheared arcade
to determine when and where the magnetic energy is released in the
classic breakout scenario.

---------------------------------------------------------
Title: A Power-law Distribution of Solar Magnetic Fields Over More
Than Five Decades in Flux
Authors: Parnell, Clare; DeForest, C. E.; Hagenaar, H. J.; Johnston,
B. A.; Lamb, D. A.; Welsch, B. T.
2009SPD....40.0603P Altcode:
The surface of the Sun is covered with magnetic features observed
on many spatial scales, which evolve on differing time scales: the
largest features, sunspots, follow an 11 year cycle; the smallest
apparently follow no cycle. Magnetograms from SoHO/MDI (full disk and
high-resolution) and Hinode/SOT are analysed to determine the fluxes
of all currently observable surface magnetic features. To identify
features we use a 'clumping' algorithm, which defines a single feature
as a group of contiguous, same-sign pixels, each of which exceeds an
absolute flux cutoff. We show that, using this feature identification
method, all feature fluxes, regardless of flux strength, follow the
same distribution - a power-law with slope -1.85±0.14 - between 2x
1017 and 1023 Mx. This result implies that the
processes that determine the spatial structure of surface magnetic
features are scale-free. Hence, suggesting that either all surface
magnetic features are generated by the same mechanism, or that their
spatial structure is dominated by processes in the interior or at the
surface (e.g., fragmentation, coalescence and cancellation) that produce
a scale-free distribution. We will discuss the likelihood of these two
mechanisms for generating the powerlaw distribution of feature fluxes.

---------------------------------------------------------
Title: Reconnectionless CME Eruption: Putting the Aly-Sturrock
Conjecture to Rest
Authors: Rachmeler, L. A.; DeForest, C. E.; Kankelborg, C. C.
2009ApJ...693.1431R Altcode: 2008arXiv0812.3199R
We demonstrate that magnetic reconnection is not necessary to initiate
fast Coronal mass ejections (CMEs). The Aly-Sturrock conjecture
states that the magnetic energy of a given force-free boundary field
is maximized when the field is open. This is problematic for CME
initiation because it leaves little or no magnetic energy to drive the
eruption, unless reconnection is present to allow some of the flux to
escape without opening. Thus, it has been thought that reconnection
must be present to initiate CMEs. This theory has not been subject to
rigorous numerical testing because conventional magnetohydrodynamics
(MHD) numerical models contain numerical diffusion, which introduces
uncontrolled numerical reconnection. We use a quasi-Lagrangian
simulation technique to run the first controlled experiments of CME
initiation in the complete lack of reconnection. We find that a flux
rope confined by an arcade, when twisted beyond a critical amount,
can escape to an open state, allowing some of the surrounding arcade
to shrink, and releasing magnetic energy from the global field. This
mechanism includes a true ideal MHD instability. We conclude that
reconnection is not a necessary trigger for fast CME eruptions.

---------------------------------------------------------
Title: Solar Coronal Structure and Stray Light in TRACE
Authors: DeForest, C. E.; Martens, P. C. H.; Wills-Davey, M. J.
2009ApJ...690.1264D Altcode: 2008arXiv0808.3980D
Using the 2004 Venus transit of the Sun to constrain a semiempirical
point-spread function (PSF) for the TRACE EUV solar telescope, we
have measured the effect of stray light in that telescope. We find
that 43% of 171 Å EUV light that enters TRACE is scattered, either
through diffraction off the entrance filter grid or through other
nonspecular effects. We carry this result forward, via known-PSF
deconvolution of TRACE images, to identify its effect on analysis
of TRACE data. Known-PSF deconvolution by this derived PSF greatly
reduces the effect of visible haze in the TRACE 171 Å images, enhances
bright features, and reveals that the smooth background component of
the corona is considerably less bright (and hence more rarefied) than
might otherwise be supposed. Deconvolution reveals that some prior
conclusions about the Sun appear to have been based on stray light in
the images. In particular, the diffuse background "quiet corona" becomes
consistent with hydrostatic support of the coronal plasma; feature
contrast is greatly increased, possibly affecting derived parameters
such as the form of the coronal heating function; and essentially all
existing differential emission measure studies of small features appear
to be affected by contamination from nearby features. We speculate on
further implications of stray light for interpretation of EUV images
from TRACE and similar instruments, and advocate deconvolution as a
standard tool for image analysis with future instruments.

---------------------------------------------------------
Title: Generation, Evolution and Destruction of Solar Magnetic Fields
Authors: Keil, Stephen; Rimmele, Thomas; DeForest, Craig
2009astro2010S.153K Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Quiet-Sun: A Comparison of MDI and SOT Fluxes
Authors: Parnell, C. E.; Deforest, C. E.; Hagenaar, H. J.; Lamb,
D. A.; Welsch, B. T.
2008ASPC..397...31P Altcode:
The SOT-NFI on Hinode has both higher resolution and better sensitivity
than MDI on SOHO. Line-of-sight magnetograms of the quiet Sun taken
simultaneously by both MDI and SOT are investigated to show how the
observed flux differs between the two instruments. We find that: (i)
the total unsigned flux observed by SOT is approximately 50% greater
than that observed by MDI and (ii) the total signed flux remains
approximately constant. Thus, the extra flux observed by SOT is made
up of equal amounts of positive and negative flux. By comparing the
observed flux distributions from MDI and SOT we find that the extra flux
is contained in features with fluxes less than the smallest observed
by MDI. Indeed, the smallest features in SOT have just ≥ 10^{16} Mx,
a factor of thirty less than the smallest observed by MDI. The
distributions of feature fluxes observed by the two instruments are
also compared. We find that by using a `clumping' algorithm, which
counts a single `flux massif' as one feature, the fluxes in MDI and
SOT follow the same distribution - a power-law - between 2× 10^{17}
and 10^{20} Mx. Thus, the mechanism producing network and intranetwork
features appears to be the same. Furthermore, the power-law index of
this distribution is found to be -1.85. This value is neither the
Kolomogrov -5/3 slope of hydrodynamic turbulence nor the Krichenen
-2 slope of magneto-hydrodynamic turbulence, although both of these
numbers may be within the error bars of our analysis.

---------------------------------------------------------
Title: WHI Targeted Campaigns on Coronal Holes and Quiet Sun: High
Resolution Observations of the Lower Atmosphere With IBIS
Authors: Cauzzi, G.; Reardon, K. P.; Rimmele, T.; Tritschler, A.;
Uitebroek, H.; Woeger, F.; Deforest, C.; McIntosh, S.
2008AGUSMSH51A..02C Altcode:
The Interferometric BIdimensional Spectrometer (IBIS) is a dual
Fabry-Perot instrument installed at the Dunn Solar Telescope that allows
two-dimensional spectroscopic observations in a variety of spectral
lines. The IBIS/DST will participate in the WHI targeted campaigns
on coronal holes (April 3-9) and quiet Sun dynamics (April 10-16)
performing simultaneous high-resolution observations of the dynamics of
the photosphere and chromosphere in the coordinated targets. The aim is
to obtain insights on the role of the lower atmosphere's dynamics and
energetics into the structuring of the coronal plasma and, possibly,
into the origin of the solar wind. In this paper we will present the
observations obtained as well as first results, and attempt to relate
them with recent work performed on quiet Sun chromospheric dynamics.

---------------------------------------------------------
Title: The Small-Scale Field Measured With Hinode/SOT and Feature
Tracking: Where is the mixed- polarity flux?
Authors: Deforest, C. E.; Lamb, D. A.; Berger, T.; Hagenaar, H.;
Parnell, C.; Welsch, B.
2008AGUSMSP51D..01D Altcode:
We report on the results of the first feature tracking study of
the solar magnetic field with Hinode/SOT. We processed a SOT Na-D
line-of-sight magnetogram sequence with five different magnetic
tracking codes. The SOT data allow us to probe the evolving magnetic
field on the granular scale for hours at a time, something that was
not possible with either ground-based observations (which are limited
to short periods of good seeing) or prior space-based observations
(which are limited to arcsecond spatial scales). We find that the field
is much less mixed than previously supposed: while Hinode resolves
small-scale structure within features that, to SOHO/MDI, would
appear as monolithic flux concentrations, this substructure has but
a single sign. Furthermore, the average distance between identifiable
flux concentrations of opposite sign remains nearly unchanged at the
higher resolution, a result that is quite surprising in light of the
common picture of a sea of strong mixed-polarity flux concentrations
dotting the inter-granular lanes. We discuss possible mechanisms for
this surprising result, and implications for the small-scale dynamo.

---------------------------------------------------------
Title: The Effect of Scattered Light on EUV Coronal Observations
Authors: Deforest, C. E.
2008AGUSMSP54A..03D Altcode:
I have measured the stray light profile of the TRACE 171 A channel
using the 2004 Venus occultation data. I find that ~35 percent of the
incident EUV is scattered into a kernel with over 200" diameter. This
is nearly twice the estimated energy of the known diffraction pattern
from the TRACE aluminum filter support grids. Deconvolving with the
fitted PSF greatly improves contrast in TRACE images and may affect
scientific results derived from them. I conclude that PSF measurement
and deconvolution is necessary for correct interpretation of images
not just from TRACE but other spaceborne telescopes, note that the
night-time and ground-based solar observing communities have already
adopted stray light deconvolution as a standard procedure, and call
for deconvolution as a standard part of the data reduction pipeline
from future solar space missions.

---------------------------------------------------------
Title: Modeling Coronal Jets with FLUX
Authors: Rachmeler, L. A.; Pariat, E.; Antiochos, S. K.; Deforest,
C. E.
2008AGUSMSP43B..01R Altcode:
We report on a comparative study of coronal jet formation with and
without reconnection using two different simulation strategies. Coronal
jets are features on the solar surface that appear to have some
properties in common with coronal mass ejections, but are less
energetic, massive, and broad. Magnetic free energy is built up over
time and then suddenly released, which accelerates plasma outward in
the form of a coronal jet. We compare results from the ARMS adaptive
mesh and FLUX reconnection-less codes to study the role of reconnection
in this system. This is the first direct comparison between FLUX and
a numerical model with a 3D spatial grid.

---------------------------------------------------------
Title: Solar Magnetic Tracking. II. The Apparent Unipolar Origin of
Quiet-Sun Flux
Authors: Lamb, D. A.; DeForest, C. E.; Hagenaar, H. J.; Parnell,
C. E.; Welsch, B. T.
2008ApJ...674..520L Altcode:
We investigate the origin of small-scale flux concentrations in the
quiet Sun. In apparent violation of the physical requirement for
flux balance, 94% of the features containing newly detected flux
are unipolar at a resolution of 1.2”. We analyze 2619 of these
apparent unipolar emergences in an image sequence from the SOHO MDI
magnetograph and compare the ensemble average to a model of asymmetric
bipolar emergence that could in principle hide opposing flux under
the noise floor of MDI. We examine the statistical consequences of
this mechanism and find that it cannot be responsible for more than
a small fraction of the unipolar emergences. We conclude that the
majority of the newly detected flux in the quiet Sun is instead due
to the coalescence of previously existing but unresolved flux into
concentrations that are large and strong enough to be detected. We
estimate the rate of coalescence into arcsecond-scale magnetic
features averaged over the solar surface to be 7 × 1021
Mx hr-1, comparable to the reported flux injection rate
due to ephemeral regions. This implies that most flux in the solar
network has been processed by very small scale shredding, emergence,
cancellation, and/or coalescence that is not resolved at 1.2”, and
it suggests that currently unresolved emergences may be at least as
important as ephemeral region emergences to the overall flux budget.

---------------------------------------------------------
Title: The effect of reconnection on a confined flux rope
Authors: Rachmeler, L. A.; Deforest, C. E.; Kankelborg, C. C.
2007AGUFMSH31A0233R Altcode:
Coronal mass ejections are among the most energetic events in our
solar system, but their initiation mechanisms are still not well
known. One possibility is loss of stability of a twisted flux rope
confined by an overlying arcade. We present here a continuation of
our research studying the role of reconnection on this system. We
examine the relationship between critical-current reconnection and
stability of a simple confined flux rope in simulations free from
numerical reconnection. The current work focuses on imposing various
reconnection rates on the system to determine how reconnection effects
the stability of the confined rope.

---------------------------------------------------------
Title: Feature Tracking of Hinode Magnetograms
Authors: Lamb, D.; Deforest, C. E.; Hagenaar, H. J.; Parnell, C. E.;
Welsch, B. T.
2007AGUFMSH53A1066L Altcode:
We present results of applying feature tracking to a sequence of Hinode
magnetograms. The single line wing Na D 5896 magnetograms have a high
signal-to-noise ratio, allowing the detection of flux approximately
30 times weaker than in MDI magnetograms. We find evidence that, even
with Hinode's improved resolution and sensitivity, we do not always
detect the bipolar emergence of new magnetic flux. This suggests that
we have not reached the ultimate resolution to observe the fundamental
flux generation processes in the photosphere.

---------------------------------------------------------
Title: Solar Magnetic Tracking. I. Software Comparison and Recommended
Practices
Authors: DeForest, C. E.; Hagenaar, H. J.; Lamb, D. A.; Parnell,
C. E.; Welsch, B. T.
2007ApJ...666..576D Altcode: 2007arXiv0704.2921D
Feature tracking and recognition are increasingly common tools for
data analysis, but are typically implemented on an ad hoc basis
by individual research groups, limiting the usefulness of derived
results when selection effects and algorithmic differences are not
controlled. Specific results that are affected include the solar
magnetic turnover time, the distributions of sizes, strengths, and
lifetimes of magnetic features, and the physics of both small scale flux
emergence and the small-scale dynamo. In this paper, we present the
results of a detailed comparison between four tracking codes applied
to a single set of data from SOHO/MDI, describe the interplay between
desired tracking behavior and parameterization tracking algorithms,
and make recommendations for feature selection and tracking practice
in future work.

---------------------------------------------------------
Title: Are “EIT Waves” Fast-Mode MHD Waves?
Authors: Wills-Davey, M. J.; DeForest, C. E.; Stenflo, J. O.
2007ApJ...664..556W Altcode: 2007arXiv0704.2828W
We examine the nature of large-scale, coronal, propagating wave
fronts (“EIT waves”) and find they are incongruous with solutions
using fast-mode MHD plane-wave theory. Specifically, we consider the
following properties: nondispersive single pulse manifestations,
observed velocities below the local Alfvén speed, and different
pulses which travel at any number of constant velocities, rather than
at the “predicted” fast-mode speed. We discuss the possibility of
a soliton-like explanation for these phenomena, and show how it is
consistent with the above-mentioned aspects.

---------------------------------------------------------
Title: Fluxon Modeling of Eruptive Events With and Without
Reconnection
Authors: DeForest, Craig; Rachmeler, L.; Davey, A.; Kankelborg, C.
2007AAS...210.5305D Altcode: 2007BAAS...39..165D
Fluxon MHD models represent the coronal magnetic field as a "skeleton"
of discretized field lines. This quasi-Lagrangian approach eliminates
numerical resistivity and allows 3-D time-dependent plasma simulation in
a desktop workstation.Using our fluxon code, FLUX, we have demonstrated
that ideal MHD instabilities can drive fast eruptive events even in the
complete absence of magnetic reconnection. The mechanism ("herniation")
is probably not the main driver of fast CMEs but may be applicable to
microjets, macrospicules, or other small scale events where vortical
flows are present in the solar atmosphere. In this presentation, we use
time-dependent simulations to demonstrate energy release in several
idealized plasma systems with and without magnetic reconnection.This
work was funded by NASA's LWS and SHP-SR&amp;T programs.

---------------------------------------------------------
Title: On the Size of Structures in the Solar Corona
Authors: DeForest, C. E.
2007ApJ...661..532D Altcode: 2006astro.ph.10178D
Fine-scale structure in the corona appears not to be well resolved by
current imaging instruments. Assuming this to be true offers a simple
geometric explanation for several current puzzles in coronal physics,
including the apparent uniform cross section of bright threadlike
structures in the corona, the low EUV contrast (long apparent
scale height) between the top and bottom of active region loops,
and the inconsistency between loop densities derived by spectral and
photometric means. Treating coronal loops as a mixture of diffuse
background and very dense, unresolved filamentary structures addresses
these problems with a combination of high plasma density within the
structures, which greatly increases the emissivity of the structures,
and geometric effects that attenuate the apparent brightness of the
feature at low altitudes. It also suggests a possible explanation for
both the surprisingly high contrast of EUV coronal loops against the
coronal background, and the uniform “typical” height of the bright
portion of the corona (about 0.3 Rsolar) in full-disk EUV
images. Some ramifications of this picture are discussed, including
an estimate (10-100 km) of the fundamental scale of strong heating
events in the corona.

---------------------------------------------------------
Title: CMEs Driven by Flux Rope Herniation
Authors: Rachmeler, Laurel; DeForest, C. E.
2007AAS...210.2908R Altcode: 2007BAAS...39R.138R
Much numerical work has been done on the magnetic kink instability as
a CME driver, but thus far it is all subject to numerical diffusion
which can bias results toward eruption. We present further results on
this instability in the absence of reconnection. We have found that
a highly twisted metastable magnetic configuration consisting of a
fluxrope contained by an arcade is capable of creating an impulsive
CME through herniation and without any reconnection.

---------------------------------------------------------
Title: Magnetic Network Formation Due to Sub-arcsecond Flux Processing
Authors: Lamb, Derek; DeForest, C. E.; Parnell, C. E.; Hagenaar,
H. J.; Welsch, B. T.
2007AAS...210.9213L Altcode: 2007BAAS...39Q.210L
Kinematic models of solar magnetic network formation typically
employ the breakup of ephemeral regions by granular and supergranular
flow. We show that the coalescence of sub-arcsecond-scale magnetic
flux concentrations into features detectable with MDI is responsible
for injecting as much flux into the magnetic network as the published
emergence rate of ephemeral regions. We also show that the few fresh
bipoles we do detect have no preferential alignment, and thus violate
Joy's law at the arcsecond scale. These two items suggest that at least
half of the flux that makes its way into the network has been processed
at spatial scales below 1 arcsecond, indicative of a local dynamo.

---------------------------------------------------------
Title: The Sensitivity of Hybrid Differential Stereoscopy for
Spectral Imaging
Authors: DeForest, Craig E.; Kankelborg, Charles C.
2007arXiv0704.2058D Altcode: 2007arXiv0704.2058K
Stereoscopic spectral imaging is an observing technique that affords
rapid acquisition of limited spectral information over an entire image
plane simultaneously. Light from a telescope is dispersed into multiple
spectral orders, which are imaged separately, and two or more of the
dispersed images are combined using an analogy between the (x,y,\lambda)
spectral data space and conventional (x,y,z) three-space. Because
no photons are deliberately destroyed during image acquisition, the
technique is much more photon-efficient in some observing regimes than
existing techniques such as scanned-filtergraph or scanned-slit spectral
imaging. Hybrid differential stereoscopy, which uses a combination of
conventional cross-correlation stereoscopy and linear approximation
theory to extract the central wavelength of a spectral line, has been
used to produce solar Stokes-V (line-of-sight) magnetograms in the
617.34 nm Fe I line, and more sophisticated inversion techniques are
currently being used to derive Doppler and line separation data from
EUV images of the solar corona collected in the neighboring lines
of He-II and Si-XI at 30.4 nm. In this paper we develop an analytic
a priori treatment of noise in the line shift signal derived from
hybrid differential stereoscopy. We use the analysis to estimate
the noise level and measurement precision in a high resolution solar
magnetograph based on stereoscopic spectral imaging, compare those
estimates to a test observation made in 2003, and discuss implications
for future instruments.

---------------------------------------------------------
Title: Fluxon modeling of low-beta plasmas
Authors: Deforest, C. E.; Kankelborg, C. C.
2007JASTP..69..116D Altcode: 2007JATP...69..116D; 2006astro.ph..9508D
We have developed a new, quasi-Lagrangian approach for numerical
modeling of magnetohydrodynamics in low to moderate β plasmas such
as the solar corona. We introduce the concept of a “fluxon”, a
discretized field line. Fluxon models represent the magnetic field as
a skeleton of such discrete field lines, and interpolate field values
from the geometry of the skeleton where needed, reversing the usual
direction of the field line transform. The fluxon skeleton forms
the grid for a collection of 1-D Eulerian models of plasma along
individual flux tubes. Fluxon models have no numerical resistivity,
because they preserve topology explicitly. Our prototype code, FLUX,
is currently able to find 3-D nonlinear force-free field solutions with
a specified field topology, and work is ongoing to validate and extend
the code to full magnetohydrodynamics. FLUX has significant scaling
advantages over conventional models: for “magnetic carpet” models,
with photospheric line-tied boundary conditions, FLUX simulations
scale in complexity like a conventional 2-D grid although the full
3-D field is represented. The code is free software and is available
online. In this current paper we introduce fluxons and our prototype
code, and describe the course of future work with the code.

---------------------------------------------------------
Title: Fluxon Modeling of Active Region Evolution
Authors: Deforest, C. E.; Kankelborg, C. C.; Davey, A. R.; Rachmeler,
L.
2006AGUFMSH31B..07D Altcode:
We present current results and status on fluxon modeling of free
energy buildup and release in active regions. Our publicly available
code, FLUX, has the unique ability to track magnetic energy buildup
with a truly constrained topology in evolving, nonlinear force-free
conditions. Recent work includes validation of the model against Low
&amp;Lou force-free field solutions, initial evolution studies of
idealized active regions, and inclusion of locally parameterized
reconnection into the model. FLUX is uniquely able to simulate
complete active regions in 3-D on a single workstation; we estimate
that a parallelized fluxon model, together with computer vision code
to ingest solar data, could run faster than real time on a cluster
of \textasciitilde 30 CPUs and hence provide a true predictive space
weather model in the style of predictive simulations of terrestrial
weather.

---------------------------------------------------------
Title: CME Initiation due to the Kink Instability in the Absence
of Reconnection
Authors: Rachmeler, L. A.; Deforest, C. E.
2006AGUFMSH33B0402R Altcode:
We present results from a controlled numerical experiment to determine
whether CME onset requires reconnection or can be driven primarily
by loss of magnetic equilibrium. We have simulated kink-unstable
CME liftoff in the complete absence of numerical reconnection by
inducing twist in a line-tied photospheric boundary using a fluxon
simulation code. Our initial results suggest that it is possible to
drive slow CMEs entirely via the kink instability even in the absence
of a large reconnection event such as breakout or a solar flare. We
further describe ongoing work, which includes studying the relative
importance of reconnection and of mass draining on CME onset.

---------------------------------------------------------
Title: Goals and Progress of the LWS Focused Science Topic on the
CME--ICME Connection
Authors: Mikic, Z.; Deforest, C.; Devore, R.; Georgoulis, M.; Jackson,
B.; Nitta, N.; Pizzo, V.; Odstrcil, D.
2006AGUFMSH21B..05M Altcode:
Our team addresses the NASA Living With a Star (LWS) Focused Science
Topic "to determine the solar origins of the plasma and magnetic flux
observed in an interplanetary Coronal Mass Ejection (ICME)." In short,
this team is examining the CME--ICME connection. Our team was formed
as a result of awards from the LWS Targeted Research &amp;Technology
competition in the fall of 2004. Our team is investigating the detailed
relationship between the plasma and magnetic fields in active regions,
the source regions of CMEs, and subsequent in situ measurements in
interplanetary magnetic clouds. We plan to study this connection through
detailed numerical simulations of CME initiation and propagation,
theoretical investigations, and studies of the properties of active
regions, CMEs, and magnetic clouds. We will discuss the goals of
our team, how it fits into NASA's missions, and our progress so
far. Research supported by NASA's Living With a Star Program.

---------------------------------------------------------
Title: On the Origin of "Unipolar" Magnetic Flux Emergence: The
Emergence you See is not the True Emergence
Authors: Lamb, D. A.; Deforest, C. E.
2006ESASP.617E..70L Altcode: 2006soho...17E..70L
No abstract at ADS

---------------------------------------------------------
Title: Active Region Loops: Not So Strange After All
Authors: DeForest, Craig
2006SPD....37.0122D Altcode: 2006BAAS...38..219D
Active region loops are enigmatic. Despite a great deal of work many
pecularities remain hard to explain, such as their nonthermal apparent
scale height, apparent uniform thickness, extreme thermal inhomogeneity,
and rapid evolution on timescales shorter than the apparent cooling
time. All of these effects can be explained via the assumption that
bright threads in active regions do in fact follow the morphology of
the force-free field (i.e. do not have uniform thickness) but are not
fully resolved by TRACE. I find that nearly-hydrostatic, force-free
active region loops with isolated localized heating are the simplest
physical scenario for active region loop formation. In this scenario,
the threads are &gt;10x more dense than the surrounding media, with a
radiative cooling time as short as 30 seconds; the anomalous apparent
scale heights are caused by a geometric effect on unresolved (or poorly
resolved) spatial scales. In addition, the picture provides a ready
explanation both for threads' rapid appearance and disappearance in
TRACE movies and also for the surprising existence of transient, smooth,
threaded, cool active region loops in TRACE FUV images. Whether this
scenario proves true, it serves to demonstrate an important geometrical
effect that, if ignored, can cause large problems for interpretation
of EUV and FUV active region images.

---------------------------------------------------------
Title: "EIT Waves" as Coronal Solitons: Explaining The Nature of
Large-Scale Coronal Pulse Waves
Authors: Wills-Davey, Meredith; DeForest, C. E.; Stenflo, J. O.
2006SPD....37.1006W Altcode: 2006BAAS...38..238W
We find that a soliton solution is applicable in a fully non-linear,
coronal MHD environment, and the compressive component of this
solution results in a pulse wave similar to the large-scale coronal
propagating wavefronts (“EIT waves”) observed by the SOHO-EIT and
TRACE telescopes. Properties of EIT wave waves that have previously
appeared incongruous using plane-wave theory are resolved in the context
of the soliton solution. Specifically, we show: why the observed wave
speed can be expected to be less than the local Alfvén speed, how a
wave pulse can instigate loop oscillations, and how a single pulse can
be channeled to propagate through the lower corona. We also discuss
the nature of likely triggers, and find that coronal mass ejections
are an ideal wave instigator.

---------------------------------------------------------
Title: The Origin of "Unipolar" Magnetic Flux Emergence
Authors: Lamb, Derek; DeForest, C. E.
2006SPD....37.0706L Altcode: 2006BAAS...38..228L
Automated tracking of magnetograms provides the ability to detect
magnetic features in an unbiased manner. Such feature tracking shows
many apparent unipolar flux emergences. Flux conservation dictates
that this cannot be a real phenomenon and thus must be due to processes
below the detection limit of routine measurements. We use large numbers
of these apparent unipolar events to distinguish between two models
of small-scale magnetic flux formation. We find that asymmetric flux
emergence, in which the poles of the emerging flux tube have different
cross sections or incidence angles at the photosphere, can account for
at most half of the events. Convergence of like-polarity poles due to
flows at sub-resolution scales provides a better explanation for the
majority of the events.

---------------------------------------------------------
Title: Exploring the Dynamics of the Solar Corona with RAISE (Rapid
Acquisition Imaging Spectrograph Experiment)
Authors: Gantner, Brennan; Hassler, D.; DeForest, C.
2006SPD....37.0603G Altcode: 2006BAAS...38Q.226G
The Rapid Acquisition Imaging Spectrograph Experiment (RAISE)
instrument will launch fall of 2006 on a NASA sounding rocket and
contains an extremely high speed scanning-slit imaging spectrograph
to observe and analyze dynamics and heating of the solar chromosphere
and corona on time scales as short as 100 ms, with TRACE-like spatial
resolution and a velocity sensitivity of 1 km/sec. High speed imaging
from TRACE has shown that rapid motions and reconnection are central to
the physics of the transition region and corona, but cannot resolve the
differences between propagating phenomena and bulk motion. SoHO/CDS and
SoHO/SUMER have yielded intriguing measurements of motion and heating in
the solar atmosphere, and Solar-B/EIS will capture EUV spectra of flares
in progress; but no currently operating instrument can capture spectral
information in the chromosphere, transition region, or cool corona on
the 1-10 Hz time scale required for few-second cadence spectral imaging
or rapid wave motion studies. RAISE is uniquely suited to exploring
this hard-to-reach domain. The complete investigation will probe three
general topics that are accessible only with our instrument's unique
capabilities, and that can be advanced with a single rocket flight:
1) Small-scale multithermal dynamics in active-region loops; 2)
the strength, spectrum, and location of high frequency waves in the
solar atmosphere; and 3) the nature of transient brightenings in the
solar network.

---------------------------------------------------------
Title: Exploring High Time Resolution Coronal Dynamics with the
Rapid Acquisition Imaging Spectrograph (RAISE) Sounding Rocket Program
Authors: Hassler, Donald W.; DeForest, C. E.; McIntosh, S.; Slater,
D.; Ayres, T.; Thomas, R.; Scheuhle, U.; Michaelis, H.; Mason, H.
2006SPD....37.3706H Altcode:
The Rapid Acquisition Imaging Spectrograph (RAISE) is a next-generation
high resolution imaging spectrograph to study the dynamics of the
solar chromosphere and corona on time scales as short as 100 ms. High
speed imaging from TRACE has shown that rapid motions and reconnection
are central to the physics of the transition region and corona, but
cannot resolve the differences between propagating phenomena and bulk
motion. SoHO/CDS and SoHO/SUMER have yielded intriguing measurements
of motion and heating in the solar atmosphere, and Solar-B/EIS will
capture EUV spectra of flares in progress; but no currently planned
instrument can capture spectral information in the chromosphere,
transition region, or cool corona on the 1-10 Hz time scale required for
few-second cadence spectral imaging or rapid wave motion studies. RAISE
is uniquely suited to exploring this hard-to-reach domain.The first
flight of RAISE is scheduled for October 24, 2006 (Flight 36.219 US)
and will focus on the study of high frequency, small-scale dynamics
of active region structures and the high frequency wave structure
associated with these active regions.

---------------------------------------------------------
Title: Is Reconnection Necessary for Kinked CME Onset?
Authors: Rachmeler, Laurel; DeForest, C. E.; Gibson, S. E.; Fan, Y.
2006SPD....37.0902R Altcode: 2006BAAS...38..236R
We present initial results from a controlled numerical experiment to
determine whether CME onset requires reconnection or can be driven
primarily by loss of plasma equilibrium. The early onset of the kink
instability proceeds with little reconnection in traditional MHD
simulations, but still at a nonzero rate. After the initial onset
of the instability, reconnection proceeds rapidly across the newly
formed current sheet, contributing to the ejection of the kink. We
have simulated the kink instability driven purely by loss of plasma
equilibrium - in the absence of numerical reconnection - as an early
step to understanding the role of reconnection in CME evolution.

---------------------------------------------------------
Title: Relationship between Solar Wind and Coronal Heating: Scaling
Laws from Solar X-Rays
Authors: Schwadron, N. A.; McComas, D. J.; DeForest, C.
2006ApJ...642.1173S Altcode:
Pevtsov et al. recently showed that the luminosity of solar and stellar
X-rays from closed magnetic structures scales nearly linearly with
magnetic flux over 12 decades. We show here that the total power
available to accelerate the solar wind also scales linearly with
magnetic flux, provided that its sources inject a roughly constant
energy per particle prior to losses from heat conducted by electrons
into radiation. Using a recently developed model of the solar wind
energy source and particle source, we calculate the available solar
wind power and convert it into an equivalent X-ray luminosity to explore
whether the same process that drives solar wind may also power coronal
heating. The quantitative results agree remarkably well with the Pevtsov
et al. X-ray observations and with GOES X-ray observations over almost
two solar cycles from 1985 to 2004. The model for the solar wind energy
and particle source relies on the continual reconfiguration of the
supergranular network through the emergence of small bipolar or more
complex closed magnetic fields. This naturally leads to an energy flux
proportional to field strength on large-scale field structures with
field strengths larger than the emerging flux. We conclude that the
sources of energy for the solar wind and coronal heating are linked,
likely through the emergence of new magnetic flux that continually
reconfigures large-scale solar magnetic fields and powers and heats
the corona.

---------------------------------------------------------
Title: Initial fluxon models of CME onset: loss-of-equilibrium,
breakout, tether-cutting
Authors: Deforest, C.
2005AGUFMSH13A0277D Altcode:
I will present results from initial models of CME onset using a new
force-free magnetic evolution code, FLUX, that uses the novel fluxon
approach to MHD modeling. FLUX is a quasi-Lagrangian solver that is
free of numerical reconnection and that I am making available as free
software. It is currently suitable for studying evolving force-free
equilibria in the presence of only controlled reconnection; development
work is ongoing to add plasma static and dynamic forces. I plan to
consider three simple configurations typical of three current genres
of CME onset model: loss of equilibrium under smooth motion by the
photosphere; "tether-cutting" (reconnection of a containment field
underneath a twisted prominence field); and "breakout" (reconnection
of a containment field above a twisted prominence field). In each case
I will estimate the magnetic energy available to accelerate mass,
and discuss the resulting shape of the remnant open field regions
("dimming regions") after liftoff.

---------------------------------------------------------
Title: On the Magnetic Correspondence between the Photosphere and
the Heliosphere
Authors: Deforest, C. E.; Hassler, D. M.; Schwadron, N. A.
2005SoPh..229..161D Altcode:
The solar magnetic field maps every point in the corona to a
corresponding place on the solar surface. Identifying the magnetic
connection map is difficult at low latitudes near the heliospheric
current sheet, but remarkably simple in coronal hole interiors. We
present a simple analytic magnetic model (`pseudocurrent extrapolation')
that reproduces the global structure of the corona, with significant
physical advantages over other nearly analytic models such as
source-surface potential field extrapolation. We use the model to
demonstrate that local horizontal structure is preserved across
altitude in the central portions of solar coronal holes, up to at
least 30 Rs, in agreement with observations. We argue that
the preserved horizontal structure may be used to track the magnetic
footpoint associated with the location of a hypothetical spacecraft
traveling through the solar corona, to relate in situ measurements of
the young solar wind at ∼10-30 Rs to particular source
regions at the solar surface. Further, we discuss the relationship
between readily observable geometrical distortions and physical
parameters of interest such as the field-aligned current density.

---------------------------------------------------------
Title: Destruction Mechanisms of Quiet-Sun Magnetic Flux
Authors: Lamb, D. A.; Deforest, C. E.; Hagenaar, H. J.; Parnell,
C. E.; Welsch, B. T.
2005AGUSMSP41B..02L Altcode:
We use SWAMIS, a freely available magnetic feature tracking suite,
to analyze the destruction of solar small-scale magnetic flux. We
track a sequence of high resolution MDI magnetograms to find the
destruction rates in a patch of quiet sun. We state criteria for
defining the individual magnetochemical destruction mechanisms
of merging, cancellation, and disappearance, and determine the
contribution of each process to the removal of detected flux from the
photosphere. Destruction mechanisms are important to determine because,
together with formation mechanisms, they provide information as to
the nature of the small-scale dynamo. We present preliminary results
and discuss the implications of these rates on models of quiet-sun
magnetic flux generation.

---------------------------------------------------------
Title: High-Frequency Waves Detected in the Solar Atmosphere
Authors: DeForest, C. E.
2004ApJ...617L..89D Altcode:
A spectrum of weakly guided waves in the solar atmosphere at frequencies
as high as 100 mHz (10 s period) has been detected with high-cadence
solar image sequences from the Transition Region and Coronal Explorer
(TRACE) spacecraft. The waves are visible in the TRACE 1600 Å far-UV
passband and were detected as faint ridges in an energy spectrum
produced by Fourier transformation of subfields of TRACE image
sequences. They have phase speeds as high as 1 Mm s-1 and
group speeds of ~100 km s-1. From the 1600 Å data alone, it
is not possible to determine whether the waves are in the chromosphere
or transition region. The waves are not energetically significant to
the chromosphere but may be significant in the transition region. Two
possible excitation mechanisms, small-scale magnetic reconnection or
chromospheric shock formation, are identified and will guide future
work. The waves may prove to be a useful probe into local conditions
and energy release into the solar atmosphere.

---------------------------------------------------------
Title: Stereoscopic Spectroscopy for Efficient Spectral Imaging
and Magnetography
Authors: DeForest, Craig; Elmore, D. F.; Bradford, M. P.; Elrod, J.;
Gilliam, D. L.
2004ApJ...616..600D Altcode:
Stereoscopic imaging spectroscopy is a novel technique that uses
multiple spectral orders and stereoscopic reconstruction to eliminate
the need for a slit in a dispersive spectrograph, potentially
increasing photon efficiency by 1-2 orders of magnitude compared with
conventional spectral imaging. We present advances in stereoscopic
reconstruction, allowing detection of the first moments of a spectral
line simultaneously over a complete two-dimensional image plane. Using
the Advanced Stokes Polarimeter on the Dunn Solar Telescope at the
National Solar Observatory, we have created the first solar magnetograms
made with this technique. With a simple prototype optical layout, we
were able to generate Stokes V magnetograms using the Fe I photospheric
absorption line at 617.34 nm (6173.4 Å). We calculate that an optimized
instrument using this technique could acquire solar magnetograms with
~10 G rms shot noise in 150 ms using this spectral line at the host
telescope's diffraction limit. Stereoscopic techniques are useful not
only for the solar photosphere but also for photon-starved imaging
spectroscopy in general.

---------------------------------------------------------
Title: High Time Cadence Observations with the Rapid Acquisition
Imaging Spectrograph (RAISE) Rocket Program
Authors: Ayres, T. R.; Hassler, D. M.; Slater, D.; DeForest, C. E.;
Mason, H.; McIntosh, S.; Thomas, R. J.
2004AAS...204.9704A Altcode: 2004BAAS...36..828A
The Rapid Acquisition Imaging Spectrograph (RAISE) is a next-generation
high resolution imaging spectrograph scheduled to fly on a NASA sounding
rocket in 2006 to study the dynamics of the solar chromosphere and
corona on time scales as short as 100 ms. High speed imaging from
TRACE has shown that rapid motions and reconnection are central to the
physics of the transition region and corona, but cannot resolve the
differences between propagating phenomena and bulk motion. SoHO/CDS and
SoHO/SUMER have yielded intriguing measurements of motion and heating
in the solar atmosphere, and Solar-B/EIS will capture EUV spectra of
flares in progress; but no currently planned instrument can capture
spectral information in the chromosphere, transition region, or cool
corona on the ∼ 1-10 Hz time scale required for few-second cadence
spectral imaging or rapid wave motion studies. RAISE is uniquely suited
to exploring this hard-to-reach domain. This work is supported
by NASA Grant NNG04WC01G to the Southwest Research Institute.

---------------------------------------------------------
Title: Clustering of the Small-Scale Field
Authors: DeForest, C. E.; Lamb, D. A.
2004AAS...204.2008D Altcode: 2004BAAS...36..687D
The face of the Sun is covered by small ephemeral magnetic regions that
form, interact, and disappear on spatial scales of a few megameters and
time scales of a few hours. By examining the history of each ephemeral
region, it is possible to make inferences about the nature of the
small-scale dynamo. We have examined timeseries of MDI magnetic data
with a sensitive tracking code. We are able to resolve discrepancies
in the size distribution of flux elements as determined by two other
tracking efforts (those of Hagenaar and of Parnell). We find that
only a small percentage of ephemeral regions actually emerge intact:
the dominant process on small scales is asymmetric coalescence,
suggesting that supergranular scale dynamo action plays only a minor
role in the creation and maintenance of the network. We also report
on a first-order clustering analysis of ephemeral regions, and discuss
its implications for the origin of the “magnetic carpet”.

---------------------------------------------------------
Title: A Soliton Solution for the Solar Corona: “EIT Waves”
Explained
Authors: Wills-Davey, M. J.; DeForest, C. E.; Stenflo, J. O.
2004AAS...204.2901W Altcode: 2004BAAS...36..695W
Many aspects of “EIT wave” observations have proved incongruous with
linear, plane-wave solutions. We find that solitons, rather than plane
waves, produce a viable non-linear MHD solution for a single-pulse
coronal compression wave. Aspects of the soliton solution describe
properties of EIT waves, in particular: \begin{itemize} coherence
and integrity over large distances, propagation velocities
that can be substantially slower than expected Alfvén or fast-mode
speeds, and displacements that can potentially instigate loop
oscillations. Additionally, this solution's very non-linearity may
explain why EIT waves are so strongly correlated with coronal mass
ejections. This research was funded by a grant from NASA.

---------------------------------------------------------
Title: Magnetic Element Tracking and Clustering Analysis
Authors: Lamb, D. A.; DeForest, C. E.
2004AAS...204.3710L Altcode: 2004BAAS...36R.710L
We have developed flux concentration tracking software to track and
identify flux concentration behavior and origin events in photospheric
magnetogram sequences. The tracking software is switchable to test and
compare the behavior of two existing tracking codes, those of Hagenaar
et al. (1999) and Parnell (2002). We present initial results from the
use of the software on a deep-field sequence of MDI magnetograms. In
particular, the two tracking methods yield significantly different
distributions of flux concentration sizes. Furthermore, based on the
ratio of coherent and incoherent origin of magnetic flux concentrations
in a sequence of deep-field MDI magnetograms, it appears that ephemeral
regions are not typically formed by emergence but rather by random
coalescence of groups of smaller, unresolved flux concentrations. Hence,
the size distribution of the solar network magnetic field may not be
determined by the scale of the small-scale dynamo but rather by the
clustering statistics of magnetic field elements in the surface flow
field. We present a preliminary analysis and discuss the implications
of flux emergence clustering in the quiet sun.

---------------------------------------------------------
Title: On Re-sampling of Solar Images
Authors: DeForest, C. E.
2004SoPh..219....3D Altcode:
Digital image data are now commonly used throughout the field of
solar physics. Many steps of image data analysis, including image
co-alignment, perspective reprojection of the solar surface, and
compensation for solar rotation, require re-sampling original telescope
image data under a distorting coordinate transformation. The most common
image re-sampling methods introduce significant, unnecessary flaws
into the data. More correct techniques have been known in the computer
graphics community for some time but remain little known within the
solar community and hence deserve further presentation. Furthermore,
image distortion under specialized coordinate transformations is
a powerful analysis technique with applications well beyond image
resizing and perspective compensation. Here I give a brief overview
of the mathematics of data re-sampling under arbitrary distortions,
present a simple algorithm for optimized re-sampling, give some
examples of distortion as an analysis tool, and introduce scientific
image distortion software that is freely available over the Internet.

---------------------------------------------------------
Title: Future Observations with the Rapid Acquisition Imaging
Spectrograph (RAISE)
Authors: Hassler, D. M.; Deforest, C. E.; Slater, D.; Ayres, T.;
Mason, H.; McIntosh, S.; Thomas, R.
2004cosp...35.2280H Altcode: 2004cosp.meet.2280H
The Rapid Acquisition Imaging Spectrograph (RAISE) is a next-generation
high resolution imaging spectrograph scheduled to fly on a NASA sounding
rocket in 2006 to study the dynamics of the solar chromosphere and
corona on time scales as short as 100 ms. High speed imaging from TRACE
has shown that rapid motions and reconnection are central to the physics
of the transition region and corona, but cannot resolve the differences
between propagating phenomena and bulk motion. SoHO/CDS and SoHO/SUMER
have yielded intriguing measurements of motion and heating in the
solar atmosphere, and Solar-B/EIS will capture EUV spectra of flares
in progress; but no currently planned instrument can capture spectral
information in the chromosphere, transition region, or cool corona
on the ~1-10 Hz time scale required for few-second cadence spectral
imaging or rapid wave motion studies. RAISE is uniquely suited to
exploring this hard-to-reach domain.

---------------------------------------------------------
Title: Magnetic Element Tracking and the Small-Scale Solar Dynamo
Authors: Lamb, D.; Deforest, C. E.
2003AGUFMSH42B0530L Altcode:
We have developed flux concentration tracking software to track and
identify flux concentration behavior and origin events in photospheric
magnetogram sequences. The tracking software is switchable to test and
compare the behavior of two existing tracking codes, those of Hagenaar
et al. (1999) and Parnell (2002). We present initial results from the
use of the software on a deep-field sequence of MDI magnetograms. In
particular, the two tracking methods yield significantly different
distributions of flux concentration sizes. Furthermore, based on the
ratio of coherent and incoherent origin of magnetic flux concentrations
in a sequence of deep-field MDI magnetograms, we conclude that ephemeral
regions are not typically formed by emergence but rather by random
coalescence of groups of smaller, unresolved flux concentrations. Hence,
the size distribution of the solar network magnetic field is not
determined by the scale of the small-scale dynamo but rather by
the clustering statistics of magnetic field elements in the surface
flow field.

---------------------------------------------------------
Title: Stereoscopic Spectrosopy for Magnetic Field Measurements
Authors: Deforest, C. E.; Hassler, D. M.
2003AGUFMSH41D..07D Altcode:
We present a novel, photon-efficient technique for measuring the
Zeeman splitting of a spectral line everywhere in an image plane. The
technique, differential stereoscopy}, allows extraction of spectral
line profiles from multiple dispersed, slitless “smearogram”
images of the Sun such as are formed by a slitless, multi-order
(“stereoscopic”) spectrograph. Because stereoscopic spectrographs
admit all photons of interest, they can be over an order of magnitude
more photon-efficient than traditional techniques. We will discuss the
technique in the context of chromospheric and coronal magnetic fields,
and present results from an initial proof-of-concept photospheric test
using the ASP at the National Solar Observatory.

---------------------------------------------------------
Title: Results from the SwRI/LASP MXUVI Sounding Rocket Experiment
(Feb. 8, 2002)
Authors: Hassler, D. M.; DeForest, C. E.; Slater, D. C.; Woods, T. N.
2003SPD....34.2010H Altcode: 2003BAAS...35..845H
We present results of the Multiple XUV Imager (MXUVI) experiment from
the February 8, 2002 LASP sounding rocket flight (NASA Flight 36.192,
Tom Woods, PI). The MXUVI experiment had the dual purpose of providing
inter-calibration for the SOHO/EIT and TRACE instruments and providing
a constraint on the coronal helium abundance by direct comparison
of the coronal Ly-alpha lines of He II (304 angstroms) and H I (1216
angstroms). The MXUVI provided full-disk solar images of Fe IX/X 171
and H I Ly-alpha 1216 for inter-calibration with the SOHO/EIT and
TRACE instruments, respectively, as well as off-limb observations of
the He II 304 and H I 1216 angstrom lines to provide a constraint on
the coronal helium abundance. This work has been funded in part
by NASA under grant NAG5-5140 to Southwest Research Institute.

---------------------------------------------------------
Title: A High Frequency Wave Search using TRACE
Authors: De Forest, C. E.; De Pontieu, B. D.; Hassler, D. M.
2003SPD....34.0111D Altcode: 2003BAAS...35..807D
We report on a possible detection of 100-milliHz band fast-mode waves
in the solar chromosphere, seen with TRACE. Near the end of 2002,
TRACE collected extremely high cadence images in the 1600 Å continuum;
initial studies show a possible signature of waves propagating near
the coronal Alfveń speed with periods as low as 10 seconds. Waves at
this frequency are near the high frequency limit because the period
is only 10-100 times the ion-electron collision time. We present these
initial results and the outcome of an ongoing follow-on study.

---------------------------------------------------------
Title: EUV Solar Spectroscopic Explorer (ESSEX): Mission Concept
for a Next Generation Imaging Spectrograph
Authors: Hassler, Donald M.; DeForest, Craig E.; Slater, David C.
2003SPIE.4853...71H Altcode:
We discuss a mission concept (ESSEX) for probing energy and mass
transport in the solar atmosphere. The primary instrument on ESSEX
is a high-speed EUV imaging spectrograph designed to extract plasma
diagnostics from the small-scale, rapidly varying events that
are thought to heat the solar atmosphere. We argue that spectral
resolution is required to determine the physics that underlies the
spectacular solar coronal images returned by TRACE and other EUV imaging
telescopes. Previous and current spectrographs are severely limited in
time resolution, and we present two rapid imaging spectrograph designs
that are optimized for different tasks: the ESSEX spectrograph,
intended as a pure science instrument to identify the physical
mechanisms of energy and mass transport in generic solar features;
and a synoptic spectrograph, intended as an operational instrument to
quantify momentum and energy release in coronal mass ejections and
filament liftoff events. If flown, ESSEX will provide high cadence
observations required to trace the flow of energy through reconnection
and wave motion in the solar atmosphere. It will achieve sub-arcsecond
resolution in the transition region and corona with both spectroscopy
and imaging over a continuous temperature range from 10,000 K to 10
million K, and will sample chromospheric wave motion at frequencies
over 100 Hz.

---------------------------------------------------------
Title: Stereoscopic Spectroscopy: A New Technique for Rapid
Magnetography
Authors: Deforest, C. E.
2003ASPC..307...75D Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Book Review: Storms from the sun; the emerging science of
space weather / Joseph Henry Press, Washington, D.C., 256 pp., 2002,
ISBN 0-3090-7642-0.
Authors: DeForest, Craig
2002Ast....30l..92D Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Book Review: The Cambridge Encyclopedia of the Sun / Cambridge
University Press, New York, 256 pp., 2001, ISBN 0-521-78093-4.
Authors: DeForest, Craig
2002Ast....30c..89D Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Book Review: Storms from the sun : the emerging science of
space weather / Joseph Henry Press, 2002
Authors: Deforest, Craig
2002Ast....30...92D Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Book Review: Extreme stars: at the edge of creation / Cambridge
University Press, New York, 236 pp., 2001, ISBN 0-521-40262-X.
Authors: DeForest, Craig
2002Ast....30a..98D Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Relationships between CME's and prominences
Authors: Schmieder, B.; van Driel-Gesztelyi, L.; Aulanier, G.;
Démoulin, P.; Thompson, B.; De Forest, C.; Wiik, J. E.; Saint Cyr,
C.; Vial, J. C.
2002AdSpR..29.1451S Altcode:
We have studied the erupting prominences which were associated with
coronal mass ejections during a series of campaigns involving both
spacecraft and ground-based observatories. The evolution of the
physical conditions within the prominences was established from Hα
and magnetic field observations. Particular attention ahs been paid
to the presence of mixed amgnetic polarity in the filament channel,
the evolution of the shear of the large-scale magnetic field, and
the existence of multiple magnetic inversion lines. We conclude that
reconnection of large-scale coronal magnetic fields is responsible
for both the CME and filament eruption.

---------------------------------------------------------
Title: Solar Polar Plume Lifetime and Coronal Hole Expansion:
Determination from Long-Term Observations
Authors: DeForest, C. E.; Lamy, P. L.; Llebaria, A.
2001ApJ...560..490D Altcode:
We have generated off-limb polar synoptic charts of polar plume
evolution at various solar altitudes using EUV Imaging Telescope and
Large Angle and Spectrometric Coronagraph data from 1996 December. The
charts allow direct measurement of the altitude expansion of the solar
minimum coronal holes. We find expansion values that are consistent with
the conventional picture of superradial expansion and inconsistent with
radial expansion. Using visible red line data as a bridge between EUV
and white-light images of the corona, we are able to confirm that the
coronal structure seen at the base of the corona is preserved throughout
the considered altitude range of 1.1-3.0 Rsolar. We show that
polar plumes are episodic in nature, lasting perhaps 24 hr but recurring
for up to weeks at a time; this strengthens the picture that they are
caused by magnetic heating under the influence of supergranulation.

---------------------------------------------------------
Title: Book Review: The 23rd cycle: learning to live with a stormy
star / Columbia University Press, New York, 207 pp., 2001, ISBN
0-231-12078-8.
Authors: DeForest, Craig
2001Ast....29h..84D Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Fluxon Modeling of Force Free Magnetic Fields: Voronoi Method
Authors: DeForest, C. E.; Kankelborg, C. C.; Longcope, D. W.
2001AGUSM..SH41A18D Altcode:
We present a promising new form of quasi-Lagrangian magnetic model for
the corona, a “fluxon model”. Fluxons are discrete representations of
field lines. Fluxon-based models are similar to traditional Lagrangian
field models in that they have no numerical resistivity because
field topology is explicitly preserved. They differ from traditional
Lagrangian models in two ways: there is no fixed set of proximity
relationships between the discrete elements of the model, preventing
numerial runaway in evolving systems; and div B is explicitly maintained
at 0. In a force-free field, the magnetic pressure and tension forces
are in equilibrium. The fluxon formulation reduces determination
of the field to a relaxation process. Calculation of the magnetic
pressure and tension forces at each step in the relaxation is reduced
to a variant of known, solved problems in computational geometry. In
this presentation, we demonstrate a computationally efficient method
of calculating these forces, using an approximation to the “Voronoi
foam” of spatial neighborhoods defined by a particular collection of
fluxons. Magnetic field modeling with fluxons offers several advantages:
(1) it facilitates detailed investigation of field topology; (2)
reconnection is completely controllable, because there is no numerical
resistivity; (4) the modeled structures may be critically sampled,
raising the prospect of unprecedented computational efficiency. These
advantages together will ultimately allow explicit modeling of stability
and reconnection in complex, slowly evolving coronal features such as
polar plumes, prominences, and active regions.

---------------------------------------------------------
Title: Simultaneous Magnetographic and XUV Observations of a
Coronal Jet
Authors: McKenzie, D. E.; DeForest, C.
2001AGUSM..SH41A14M Altcode:
On 03 November 2000, a jet of hot plasma appeared in the solar corona,
and was observed by the Yohkoh Soft X-ray Telescope (SXT) and the
TRACE coronal imager. The jet of magnetically channeled plasma,
measuring over 280 megameters in length, serendipitously occurred
within the high-resolution field of view of the SOHO Michelson Doppler
Interferometer (MDI). We present the X-ray, extreme ultraviolet, and
magnetographic observations, and attempt to draw conclusions about
the evolution of the jet based upon the evolution of the magnetic field.

---------------------------------------------------------
Title: Lagrangian Modeling of Force Free Fields and Current Sheets:
Fluxon representation and the Kernel Method
Authors: Kankelborg, C. C.; Longcope, D. W.; DeForest, C. E.
2001AGUSM..SH41A17K Altcode:
In force free magnetic fields, the magnetic pressure and tension forces
are balanced. These forces may be represented in terms of arrangements
of field lines (“fluxons”). We demonstrate a novel Lagrangian
technique for modeling of force-free configurations in 2D and 3D with
and without current sheets. The fundamental computational element
in our model is the fluxon, a field-line-like entity that represents
the configuration of a finite quantity of magnetic flux. The magnetic
field in a volume is represented as a collection of fluxons, each with a
geometry defined by a connected series of points. The magnetic curvature
force is easily determined by finite differencing along a fluxon. A
smoothing kernel is used to evaluate magnetic field strength and its
gradient. By these means, the Lorentz force is determined. Relaxation
to a force free state is accomplished by displacing the fluxons in the
direction indicated by the Lorentz force. Further calculations with
the smoothing kernel allow the evaluation of stored magnetic energy
and mapping of current distributions in the volume. Magnetic field
modeling in the fluxon representation offers several advantages:
(1) it facilitates detailed investigation of field topology; (2)
reconnection is completely controllable --- it cannot occur unless
it is explicitly inserted into the model; (3) there is no numerical
resistivity; (4) current sheets are critically sampled, raising the
prospect of unprecedented computational efficiency.

---------------------------------------------------------
Title: Observation of Polar Plumes at High Solar Altitudes
Authors: DeForest, C. E.; Plunkett, S. P.; Andrews, M. D.
2001ApJ...546..569D Altcode:
Using the Large-Angle Spectrometric Coronagraph (LASCO) aboard the
Solar and Heliospheric Observatory (SOHO) spacecraft, we have imaged
polar plumes extending 30 Rsolar from disk center in the
image plane and ~45 Rsolar in three-dimensional space,
a factor of 2-3 farther than previous imaging measurements and well
into the constant-velocity regime of wind flow. We find that the plumes
maintain their overall linear morphology and density enhancement to
at least this altitude range. Using LASCO photometry and a modeled
cylindrical plume geometry, we derive the density excess within the
plumes 30 Rsolar above the Sun (in three dimensions). At
this altitude, the plumes are (2-4)×103 cm-3
above the background interplume density, with an estimated plasma β
of order 300. The excess electron densities are a factor of 20-30
greater than the average total electron density estimates obtained
from extrapolation of in situ measurements by Ulysses at 1 AU. The
contrast between the high plume excess densities that we observe and
the uniformity of the wind seen by Ulysses may best be explained by wind
models that include horizontal mixing in the lower heliosphere between
45 Rsolar and Ulysses's altitude of ~200 Rsolar.

---------------------------------------------------------
Title: Solar Activity: The Earth Sun Connection near Solar Maximum
Authors: DeForest, C.
2000AAS...197.2601D Altcode: 2000BAAS...32.1442D
The Sun is currently in the maximum activity phase of its 11-year
sunspot cycle, marking the reversal of its magnetic dipole moment
and a peak in the number of sunspots, coronal mass ejections,
and solar flares. Solar activity has long been known to affect the
Earth and its geospace environment, but detailed understanding of
the complex interaction between our star and its environment has
remained elusive because solar and planetary data have been rich
enough to identify events but not complete enough to constrain their
physics. The unprecedented number and variety of spacecraft and ground
based instruments that are observing the Sun, inner heliosphere, and
Earth is at last providing data sets that can encompass the events
of solar maximum from the detailed astrophysics of their origin, to
their effects at Earth. The data are not only spectacular; they are
also profoundly changing our understanding of the Sun's astrophysics
and of its relevance to the Earth environment.

---------------------------------------------------------
Title: The origin and development of the May 1997 magnetic cloud
Authors: Webb, D. F.; Lepping, R. P.; Burlaga, L. F.; DeForest, C. E.;
Larson, D. E.; Martin, S. F.; Plunkett, S. P.; Rust, D. M.
2000JGR...10527251W Altcode:
A complete halo coronal mass ejection (CME) was observed by the SOHO
Large-Angle and Spectrometric Coronagraph (LASCO) coronagraphs on May
12, 1997. It was associated with activity near Sun center, implying that
it was aimed earthward. Three days later on May 15 an interplanetary
shock and magnetic cloud/flux rope transient was detected at the Wind
spacecraft 190 RE upstream of Earth. The long enduring
southward magnetic fields associated with these structures triggered a
geomagnetic storm. The CME was associated with a small coronal arcade
that formed over a filament eruption with expanding double ribbons
in Hα emission. The flare was accompanied by a circular EUV wave,
and the arcade was flanked by adjacent dimming regions. We surmise
that these latter regions marked the feet of a flux rope that expanded
earthward into the solar wind and was observed as the magnetic cloud
at Wind. To test this hypothesis we determined key parameters of the
solar structures on May 12 and compared them with the modeled flux
rope parameters at Wind on May 15. The measurements are consistent
with the flux rope originating in a large coronal structure linked
to the erupting filament, with the opposite-polarity feet of the rope
terminating in the depleted regions. However, bidirectional electron
streaming was not observed within the cloud itself, suggesting that
there is not always a good correspondence between such flows and ejecta.

---------------------------------------------------------
Title: Polar Plumes
Authors: Deforest, C.
2000eaa..bookE2075D Altcode:
Polar plumes (figure 1) are thin, bright, linear structures that
are seen to emanate from the poles of the Sun during the `minimum'
phase of the solar cycle, when there are well-developed polar CORONAL
HOLES. They may be seen with the naked eye during a solar eclipse
or at any time with coronagraph instruments sensitive to visible or
ultraviolet light. When seen with visible light, they are often...

---------------------------------------------------------
Title: Solar Flares: Relation to Coronal Mass Ejections
Authors: Deforest, C.
2000eaa..bookE2294D Altcode:
SOLAR FLARES and SOLAR CORONAL MASS EJECTIONS have both been associated
with geomagnetic activity such as the AURORA, radio interference and
`geomagnetic storms' caused by large currents flowing through the
Earth's magnetosphere. They are also both associated with high fluxes
of energetic particles (`proton events') in near-Earth space. However,
they are different types of event....

---------------------------------------------------------
Title: Correction to “Change in photospheric magnetic flux during
coronal mass ejections”
Authors: Lara, Alejandro; Gopalswamy, Nat; DeForest, Craig
2000GeoRL..27.1863L Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Change in photospheric magnetic flux during coronal mass
ejections
Authors: Lara, Alejandro; Gopalswamy, Nat; DeForest, Craig
2000GeoRL..27.1435L Altcode:
We report on the variations of photospheric magnetic flux during
coronal mass ejections (CMEs). Using magneograms from the SOHO/MDI
instrument, we have computed the magnetic flux of 7 active regions and
one disappearing filament region associated with CMEs. When we plotted
the flux versus time over a period of few days before, during and after
the CME event, we found changes in the mean magnetic flux per pixel
(∼4 arcsec²), ranging from ∼0.4 to ∼3.1 × 1017 Mx,
in structures of size smaller than the active region. Flare onsets
and the filament disappearance clearly occurred during periods of
significant variations in the measured magnetic flux.

---------------------------------------------------------
Title: Magnetic Heating in Action: Life Cycles of Small Open Coronal
Structures
Authors: DeForest, C. E.
2000SPD....31.0202D Altcode: 2000BAAS...32..811D
Magnetic reconnection and the accompanying release of energy are
the prime candidate mechanism for coronal heating. Recent results
(e.g. Hagenaar, Schrijver, and Title) from the SOHO/MDI instrument
have shown that there is sufficient energy contained in the changing
small-scale magnetic field to heat the corona. However, it is not at
all clear that the continual reconnection of this “magnetic carpet”
actually releases sufficient energy into the corona. Small, isolated,
relatively long-lived structures such as coronal bright points and
polar plumes are ideal places to search for the hypothetical energy
deposition from the magnetic field into the quiet corona, because these
structures are relatively isolated from the more complex surrounding
corona. Polar plumes, in particular, require approximately continuous
input of energy to exist and hence are good model structures for the
quiet corona. High sensitivity 32-minute averaged around-the-clock
sequences of magnetograms from MDI have recently become available,
allowing the first detailed studies comparing the behavior of polar
plumes with their footpoints' detailed evolution over the complete life
cycle of several plumes. I will present data from joint TRACE/MDI and
EIT/MDI studies relating plume genesis, life, and death to changes
in the small scale magnetic configuration within the polar coronal
holes. This work was funded through the SEC Guest Investigator program
and via NASA grant NASG-5077.

---------------------------------------------------------
Title: Structure of a Large low-Latitude Coronal Hole
Authors: Bromage, B. J. J.; Alexander, D.; Breen, A.; Clegg, J. R.;
Del Zanna, G.; DeForest, C.; Dobrzycka, D.; Gopalswamy, N.; Thompson,
B.; Browning, P. K.
2000SoPh..193..181B Altcode:
Coronal holes on the Sun are the source of high-speed solar wind
streams that produce magnetic disturbances at the Earth. A series
of multi-wavelength, multi-instrument observations obtained during
the 1996 `Whole Sun Month' campaign examined a large coronal hole in
greater detail than ever before. It appeared on the Sun in August, and
extended from the north pole to a large active region in the southern
hemisphere. Its physical and magnetic structure and subsequent evolution
are described.

---------------------------------------------------------
Title: In-Flight Determination of the Plate Scale of the
Extreme-Ultraviolet Imaging Telescope
Authors: Auchère, F.; DeForest, C. E.; Artzner, G.
2000ApJ...529L.115A Altcode:
Using simultaneous observations of the Michelson Doppler Imager
and Extreme-Ultraviolet Imaging Telescope (EIT) on board the Solar
and Heliospheric Observatory spacecraft, we determined in flight
the plate scale of the EIT. We found a value of 2.629"+/-0.001"
pixel-1, in fair agreement with the 2.627"+/-0.001"
pixel-1 value deduced from recent laboratory measurements
of the focal length and much higher by 7 σ than the 2.622"
pixel-1 value of the preflight calibrations. The plate
scale is found to be constant across the field of view, confirming
the negligible distortion level predicted by the theoretical models
of the EIT. Furthermore, the 2 σ difference between our results and
the latest laboratory measurements, although statistically small, may
confirm a recent work suggesting that the solar photospheric radius
may be 0.5 Mm lower than the classically adopted value of 695.99 Mm.

---------------------------------------------------------
Title: 3-D Magnetic Configurations for Filaments and Flares: The
Role of “Magnetic Dips” and “Bald Patches”
Authors: Aulanier, G.; Schmieder, B.; van Driel-Gesztelyi, L.; Kucera,
T.; Démoulin, P.; Fang, C.; Mein, N.; Vial, J. -C.; Mein, P.; Tang,
Y. H.; Deforest, C.
2000AdSpR..26..485A Altcode:
The 3-D magnetic configuration of a filament and of a low energy
flare is reconstructed, using linear mag- netohydrostatic (lmhs)
extrapolations. In both cases, we find observational signatures
of energy release at the locations of computed “bald patches”
separatrices, characterised by field lines which are tangent to
the photosphere.The filament was observed on Sept. 25, 1996, in Hα
with the MSDP on the German VTT, Tenerife, as well as in Si IV with
SOHO/SUMER. It is modeled as a twisted flux-tube deformed by the
magnetic polarities observed with SOHO/MDI. The shape and location of
the computed dipped field lines are in good agreement with the shape of
the filament and its feet observed in Hα. Some “bald patches” (BPs)
are present where the distribution of dips reaches the photosphere. We
show that some of the large scale field lines rooted in BPs can be
related to bright fine structures in Si IV. We propose that the plasma
there is heated by ohmic dissipation from the currents expected to be
present along the BP separatrices.The flare was observed on May 18,
1994, in soft X-rays with Yohkoh/SXT, and in Hα at Mitaka (Japan). The
magnetic field is directly extrapolated from a photospheric magnetogram
from Kitt Peak Observatory. The intersections with the photosphere of
the computed separatrices match well the bright Hα ribbons. The later
are associated to three BPs, with overlaying dipped field lines. We
show that enhanced densities are present in these dips, which can be
correlated with dark Hα fibrils.Both cases show the importance of
dipped field lines and BPs in the solar atmosphere. Energy release
via ohmic dissipation as well as reconnection along BP separatrices
is proposed to provide heating observed as UV brightenings in filament
channels and even as small flares

---------------------------------------------------------
Title: Comparisons of Interplanetary Scintillation and Optical
Measurements of Solar Wind Acceleration with Model Results
Authors: Breen, A. R.; de Forest, C. F.; Thompson, B. J.; McKenzie,
J. F.; Modigliani, A.; Moran, P. J.; Williams, P. J. S.
2000AdSpR..26..781B Altcode:
Observations of the fast, high latitude solar wind show that
acceleration of the fast wind is complete by 10 solar radii (R),
while measurements from the LASCO instrument on SOHO show that most
of the acceleration takes place inside 5 R. A series of observations
were made in September 1997 using EISCAT and the C2 and C3 coronagraphs
aboard SOHO to measure the solar wind velocity profile from 3 R out to
beyond 30 R. The overlapping fields of view of the instruments allowed
direct comparisons to be made between IPS and optical estimations of
flow velocity. Together, these measurements provide strong constraints
on any model seeking to provide an explanation of the acceleration of
the fast solar wind. We present the results of a comparison between
out observations and the most recent version of the Lindau-Warsaw
solar wind acceleration model

---------------------------------------------------------
Title: Numerical Simulations of Trapped Slow Magnetosonic Waves in
Solar Coronal Plumes
Authors: Ofman, L.; Deforest, C. E.
2000AdSpR..25.1909O Altcode:
Recent observations of polar plumes in the southern solar coronal
hole by the Extreme ultraviolet Imaging Telescope (EIT) on board
the SOHO spacecraft show signatures of quasi-periodic compressional
waves. Here, we present the results of a nonlinear, 2D MHD simulation
of the slow magnetosonic waves in plumes for typical coronal conditions
consistent with observations. Our numerical simulations confirm the
interpretation of the observed intensity fluctuations as propagating
slow magnetosonic waves. On March 7 1996 DeForest and Gurman (1998)
detected quasi-periodic intensity variations of 10-20% in the EIT
Fe IX and X line emission at 171A&amp;ring that propagate outward
in several polar plumes at 75-150 km s-1 with a period of
10-15 minutes. The observed propagation velocity agrees well with the
expected sound velocity inside the plumes. The lower phase speed in
the plumes than in the ambient plasma leads to partial trapping of the
slow magnetosonic waves in the plumes. The slow magnetosonic waves may
contribute to the heating of the lower corona by compressive dissipation

---------------------------------------------------------
Title: In Flight Determination of the Plate Scale of the EIT
Authors: Auchere, F.; DeForest, C. E.; Artzner, G.
1999astro.ph.12213A Altcode:
Using simultaneous observations of the MDI and EIT instruments on
board the SoHO spacecraft, we determined in flight the plate scale
of the EIT. We found a value of 2.629+-0.001 arc seconds per pixel,
in fair agreement with the 2.627+-0.001 arc seconds per pixel value
deduced from recent laboratory measurements of the focal length, and
much higher by 7 sigma than the 2.622 arc seconds per pixel value of
the pre-flight calibrations. The plate scale is found to be constant
across the field of view, confirming the negligible distortion level
predicted by the theoretical models of the EIT. Furthermore, the 2 sigma
difference between our results and the latest laboratory measurements,
although statistically small, may confirm a recent work suggesting that
the solar photospheric radius may be 0.5 Mm lower than the classically
adopted value of 695.99 Mm.

---------------------------------------------------------
Title: Long-Term Evolution Of Emissivity And Heating In A Solar
Active Region
Authors: van Driel-Gesztelyi, L.; Thompson, B.; Démoulin, P.; Orlando,
S.; Bocchialini, K.; Oláh, K.; Kövári, Z.; Deforest, C.; Khan,
J.; Fludra, A.; Mandrini, C.
1999ESASP.446..663V Altcode: 1999soho....8..663V
We study the evolution of the heating and emissivity of an active
region from its birth throughout its decay during six solar rotations
(July-Nov. 1996). We analyse multi-wavelength and multi-instrument
data obtained from SOHO (EIT, SUMER, CDS, MDI), Yohkoh (SXT), GOES
and 10.7cm radio data from DRAO, Canada. We take one "snapshot" per
rotation at the time of the central meridian passage (CMP) of the
AR, outside of time of flares, which appears to be representative
enough to allow us to make some general conclusions about the
long-term evolution. Deriving physical parameters like intensity
(flux), temperature and emission measure of the entire AR vs. time,
we formulate mathematically the change in radiation emitted by the
decaying AR at several wavelengths. Combining the emissivity data with
the evolution of magnetic flux density as the flux is being dispersed
by small- and larger-scale convective motions, we make an attempt to
understand the physics behind the emission and heating. We also analyse
the effects of flaring on the heating of the AR, and study whether and
how the flare properties evolve during the life of the active region.

---------------------------------------------------------
Title: Polar Plumes Observed at Extreme Coronal Altitudes
Authors: Deforest, C. E.; Plunkett, S. P.
1999AAS...19410801D Altcode:
Polar plumes, unipolar high density structures in the polar coronal
holes, are key to our understanding of solar wind acceleration and
coronal heating. Because unipolar magnetic flux concentrations in
the coronal hole account for approximately 50 leaves the coronal
hole (DeForest et al., 1996), plumes (which arise from some such
concentrations) are tracers of a type of magnetic structure that
fills nearly half of the solar system at solar minimum. Plumes
have been observed up to altitudes of about 10 solar radii with the
LASCO instrument (DeForest et al., 1996), above which they fade into
the coronal background. There is some contention (Habbal and Woo,
1997; Paetzold and Bird, 1998) over whether plumes extend into the
interplanetary medium or become mixed with the interplume solar wind at
altitudes between 10 and 100 solar radii. Several mechanisms, including
the Kelvin-Helmholtz two-stream instability and cross-mode resonant
wave scattering near the alfvenic point in the wind's acceleration,
have been proposed that could break up the structure of the observed
plumes. Using the LASCO C-3 instrument aboard SOHO (Brueckner et al,
1995) to accumulate multiple images that we then recombine, we have
generated coronal images with effective exposure times in the thousands
of seconds and actual durations of less than four hours. These images
clearly show polar plumes extending to altitudes of 25 solar radii or
more, very close to the outer edge of the C-3 field of view and above
the likely alfvenic point of the wind flow.

---------------------------------------------------------
Title: Polar plumes observed at extreme coronal altitudes.
Authors: Deforest, C. E.; Plunkett, S. P.
1999BAAS...31.1241D Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Magnetic Field Evolution and Topology of an AR
Authors: Mandrini, C. H.; Deng, Y. Y.; Schmieder, B.; Démoulin, P.;
Rudawy, P.; Nitta, N.; Newmark, J.; de Forest, C.
1999ASPC..184..276M Altcode:
Active region 7968 was observed during runs of a coordinated SOHO,
Yohkoh and ground-based observatory program (Joint Observing Program,
JOP, 17). The region appeared and decayed in a seven day period (June 3
to 10, 1996). In this time, mainly during June 6, it presented a very
dynamical behaviour. Flux emerged in between the two main polarities
and Arch Filament Systems (AFS) were observed to be linked to this
emergence. We analyze the evolution of some over dark arches observed
during flux emergence, forming two systems of AFS. Modelling the
magnetic field, we find that these systems were associated to field
lines having dips tangent to the photosphere (the so called "bald
patches", BPs). We discuss their evolution in terms of emergence of
the dipped portion of the lines or of magnetic field reconnection.

---------------------------------------------------------
Title: Long-Term Magnetic Evolution of an AR and its CME Activity
Authors: van Driel-Gesztelyi, L.; Mandrini, C. H.; Thompson, B.;
Plunkett, S.; Aulanier, G.; Démoulin, P.; Schmieder, B.; de Forest, C.
1999ASPC..184..302V Altcode:
Using SOHO/MDI full-disc magnetic maps, we follow the magnetic
evolution of a solar active region for several months in the period of
July-November 1996. We extrapolate the photospheric magnetic fields in
the linear force-free approximation and match the modelled field lines
with the soft X-ray loops observed with the Yohkoh/SXT in order to
diagnose the coronal magnetic shear. We find that while the turbulent
motions diffuse the flux, the differential rotation, and possibly
twisted flux emergence, increase the magnetic shear. Flares are observed
during the first three rotations, while CME events (observed by SOHO/EIT
and LASCO) originate from this AR from its emergence throughout its
decay. Several early CMEs, while none of the late CMEs, are related to
flare events above the GOES B1 level. We find that the late CMEs occur
when the magnetic shear, after accumulating for four rotations, reaches
a high level and saturates. We propose that CME activity serves as a
valve through which the AR could get rid of excess shear and helicity.

---------------------------------------------------------
Title: Is the chromosphere hotter in coronal holes?
Authors: Gopalswamy, N.; Shibasaki, K.; Thompson, B. J.; Gurman,
J. B.; Deforest, C. E.
1999AIPC..471..277G Altcode: 1999sowi.conf..277G
Coronal holes are brighter than the quiet Sun in microwaves. Microwave
emission from the quiet Sun is optically thick thermal bremsstrahlung
from the upper chromosphere. Therefore, the optically thick layer in the
coronal hole chromosphere must be hotter than the corresponding layer
in the quiet chromosphere. We present microwave and SOHO observations
in support of this idea. Because of the availability of simultaneous
EUV and microwave images it is now possible to obtain more details
of this enigmatic phenomenon. In this paper, we highlight the primary
properties of the microwave enhancement in coronal holes and point out
some related phenomena. Finally, we summarize the possible explanations
of the radio enhancement.

---------------------------------------------------------
Title: Microwave enhancement and variability in the elephant's trunk
coronal hole: Comparison with SOHO observations
Authors: Gopalswamy, N.; Shibasaki, K.; Thompson, B. J.; Gurman, J.;
DeForest, C.
1999JGR...104.9767G Altcode:
We report on an investigation of the microwave enhancement and its
variability in the elephant's trunk coronal hole observed during the
Whole Sun Month campaign (August 10 to September 9, 1996). The microwave
images from the Nobeyama radioheliograph were compared with magnetograms
and EUV images obtained simultaneously by the Michelson Doppler imager
and the extreme ultraviolet imaging telescope (EIT) on board the SOHO
spacecraft. The combined data set allowed us to understand the detailed
structure of the microwave enhancement in the spatial and temporal
domains. We find that the radio enhancement is closely associated
with the enhanced unipolar magnetic regions underlying the coronal
hole. The radio enhancement consists of a smooth component originating
from network cell interiors and a compact component associated with
network magnetic elements. When a minority polarity is present near
a majority polarity element, within the coronal hole, the resulting
mixed polarity region is associated with a bright-point-like emission
in coronal EUV lines such as the Fe XII 195 Å. These coronal bright
points are also observed distinctly in the EIT 304 Å band, but not
in microwaves. On the other hand, the lower-temperature line emission
(304 Å) and the microwave enhancement are associated with the unipolar
magnetic flux elements in the network. We found strong time variability
of the radio enhancement over multiple timescales, consistent with the
initial results obtained by SOHO instruments. The microwave enhancement
is most probably due to temperature enhancement in the chromosphere
and may be related to the origin of solar wind.

---------------------------------------------------------
Title: Temporal Evolution and Physical Properties of North Polar
Coronal Hole from SPARTAN 201-05, SOHO, TRACE and Mk3
Authors: Guhathakurta, M.; Deforest, C.; Fisher, R. R.; Ofman, L.;
Kucera, T.; Gibson, S.; Spartan201 Team
1999AAS...194.3203G Altcode: 1999BAAS...31..870G
Polar coronal rays/plumes as long lived structures that extend out
to 6 R_sun were first observed during the first flight of SPARTAN 201
spacecraft during April 11-12 of 1993. In this paper we will present
detail observations from the WLC aboard Spartan 201 spacecraft (31
Oct.- 2 Nov.,1998) of the north polar coronal hole and comapre its
physical properties to the past three Spartan missions. We will present
comparisons of the Spartan WL observations with the Mk3 pB observations,
SOHO LASCO and EIT observations, and finally the high resolution TRACE
171 Angstroms observations, to characterize the north polar coronal
hole all the way from the base of the corona out to 30 R_sun. We will
also look for signatures of waves (quasi-period variations) in the
coronal hole plumes and interplume regions in the high cadence Spartan
pB observations obtained during this mission.

---------------------------------------------------------
Title: Slow Magnetosonic Waves in Coronal Plumes
Authors: Ofman, L.; Nakariakov, V. M.; DeForest, C. E.
1999ApJ...514..441O Altcode:
Recent observations of polar plumes in the southern solar coronal
hole by the Extreme-Ultraviolet Imaging Telescope (EIT) on board
the SOHO spacecraft show signatures of quasi-periodic compressional
waves with periods of 10-15 minutes. The relative wave amplitude
was found to increase with height in the plumes up to about 1.2
Rsolar. Using a one-dimensional linear wave equation for
the magnetosonic wave, we show that the waves are propagating and
that their amplitude increases with height. The observed propagation
velocity agrees well with the expected sound velocity inside the
plumes. We present the results of the first nonlinear, two-dimensional,
magnetohydrodynamic (MHD) simulation of the magnetosonic waves in
plumes for typical coronal conditions consistent with observations
and gravitationally stratified solar corona. We find numerically
that outward-propagating slow magnetosonic waves are trapped, and
nonlinearly steepen in the polar plumes. The nonlinear steepening of
the magnetosonic waves may contribute significantly to the heating of
the lower corona by compressive dissipation.

---------------------------------------------------------
Title: SOHO Observations of Density Fluctuations in Coronal Holes
Authors: Ofman, L.; Romoli, M.; Noci, G.; Poletto, G.; Kohl, J. L.;
Howard, R. A.; Cyr, C. St.; Deforest, C. E.
1999SSRv...87..287O Altcode:
In recent UVCS/SOHO White Light Channel (WLC) observations we found
quasi-periodic variations in the polarized brightness (pB) in the
polar coronal holes at heliocentric distances of 1.9 to 2.45 solar
radii. The motivation for the observation is the 2.5D MHD model of
solar wind acceleration by nonlinear waves, that predicts compressive
fluctuations in coronal holes. In February 1998 we performed new
observations using the UVCS/WLC in the coronal hole and obtained
additional data. The new data corroborate our earlier findings with
higher statistical significance. The new longer observations show that
the power spectrum peaks in the 10 12 minute range. These timescales
agree with EIT observations of brightness fluctuations in polar
plumes. We performed preliminary LASCO/C2 observations in an effort
to further establish the coronal origin of the fluctuations.

---------------------------------------------------------
Title: The Solar Minimum Active Region 7978, Its X2.6/1B Flare, CME,
and Interplanetary Shock Propagation of 9 July 1996
Authors: Dryer, M.; Andrews, M. D.; Aurass, H.; DeForest, C.; Galvin,
A. B.; Garcia, H.; Ipavich, F. M.; Karlický, M.; Kiplinger, A.;
Klassen, A.; Meisner, R.; Paswaters, S. E.; Smith, Z.; Tappin,
S. J.; Thompson, B. J.; Watari, S. I.; Michels, D. J.; Brueckner,
G. E.; Howard, R. A.; Koomen, M. J.; Lamy, P.; Mann, G.; Arzner, K.;
Schwenn, R.
1998SoPh..181..159D Altcode:
The first X-class flare in four years occurred on 9 July 1996. This
X2.6/1B flare reached its maximum at 09:11 UT and was located in active
region 7978 (S10° W30°) which was an old-cycle sunspot polarity
group. We report the SOHO LASCO/EIT/MDI and SOONSPOT observations before
and after this event together with Yohkoh SXT images of the flare,
radio observations of the type II shock, and GOES disk-integrated soft
X-ray flux during an extended period that included energy build-up in
this active region.

---------------------------------------------------------
Title: 3-D magnetic configurations supporting prominences. II. The
lateral feet as a perturbation of a twisted flux-tube
Authors: Aulanier, G.; Demoulin, P.; van Driel-Gesztelyi, L.; Mein,
P.; Deforest, C.
1998A&A...335..309A Altcode:
In a previous paper we have shown that a twisted flux-tube is the
most probable magnetic configuration supporting prominences. The
model interprets many observations in a natural way (in particular
the magnetic measurements in prominences and the chirality
properties). Moreover, prominence feet appear as a direct consequence
of the parasitic polarities present in the filament channel. Here we
investigate further the link between feet and parasitic polarities
by modelling explicitly these polarities. We show that the prominence
lateral feet appear naturally, above secondary photospheric inversion
lines and we describe the morphological change of feet as parasitic
polarities evolve. This approach is applied to an observed filament
in Hα with the MSDP on the German VTT (Tenerife) where SOHO/MDI
magnetograms are available. We show that the shape of the prominence
is defined by the distribution of the dips in the computed magnetic
configuration. Then we analyse the topology of the magnetic field using
the quasi-separatrix layers (QSLs) method. We describe the basic changes
in the topology as the parasitic polarities evolve, in particular
how the configuration pass from an OX to an OF topology. We find a
correspondance between the computed QSLs and some of the chromospheric
brightenings, observed around the feet of filaments in the y line (Ca
II, 8542 Angstroms). It confirms the deduced magnetic configuration
and shows that energy release is present at a low level in the complex
topology of the filament configuration.

---------------------------------------------------------
Title: Observation of Quasi-periodic Compressive Waves in Solar
Polar Plumes
Authors: DeForest, C. E.; Gurman, J. B.
1998ApJ...501L.217D Altcode:
On 1996 March 7, the Solar and Heliospheric Observatory spacecraft
conducted a multi-instrument campaign to observe polar plumes in the
south polar coronal hole. Recent time-domain analyses of EUV Imaging
Telescope images from that campaign show filamentary substructure in
the plumes, on a length scale of ~5", which changes on timescales
of a few minutes, and coherent quasi-periodic perturbations in
the brightness of Fe IX and Fe X line emission at 171 Å from the
plumes. The perturbations amount to 10%-20% of the plumes' overall
intensity and propagate outward at 75-150 km s-1, taking
the form of wave trains with periods of 10-15 minutes and envelopes
of several cycles. We conclude that the perturbations are compressive
waves (such as sound waves or slow-mode magnetosonic waves) propagating
along the plumes. Assuming that the waves are sonic yields a mechanical
energy flux of 150-400 W m-2 (1.5-4 ×105 ergs
cm-2 s-1) in the plumes.

---------------------------------------------------------
Title: Multiwavelength Observations of a Coronal Hole
Authors: Gopalswamy, N.; Shibasaki, K.; Deforest, C. E.; Bromage,
B. J. I.; Del Zanna, G.
1998ASPC..140..363G Altcode: 1998ssp..conf..363G
No abstract at ADS

---------------------------------------------------------
Title: Evolution of the Magnetic Field and Chromospheric Fine
Structure in a Filament Channel
Authors: van Driel-Gesztelyi, L.; Mein, P.; Mein, N.; Schmieder,
B.; Malherbe, J. -M.; Aulanier, G.; Démoulin, P.; Deforest, C.;
Staiger, J.
1998ASPC..155..321V Altcode: 1998sasp.conf..321V
No abstract at ADS

---------------------------------------------------------
Title: Non potentiality of coronal loops above active regions
Authors: Aulanier, G.; Schmieder, B.; Démoulin, P.; van
Driel-Gesztelyi, L.; Deforest, C.
1998ASPC..155..105A Altcode: 1998sasp.conf..105A
No abstract at ADS

---------------------------------------------------------
Title: Filament Disparition Brusque and CME - September 25-26,
1996 Event
Authors: van Driel-Gesztelyi, L.; Schmieder, B.; Aulanier, G.;
Demoulin, P.; Martens, P. C. H.; Zarro, D.; Deforest, C.; Thompson,
B.; St. Cyr, C.; Kucera, T.; Burkepile, J. T.; White, O. R.; Hanaoka,
Y.; Nitta, N.
1998ASPC..150..366V Altcode: 1998IAUCo.167..366V; 1998npsp.conf..366V
No abstract at ADS

---------------------------------------------------------
Title: 3-D Modelling of a Filament Observed in Hα and with SOHO
Authors: Aulanier, G.; Schmieder, B.; Démoulin, P.; Mein, N.; van
Driel-Gesztelyi, L.; Mein, P.; Vial, J. C.; Deforest, C.
1998ESASP.417..217A Altcode: 1998cesh.conf..217A
No abstract at ADS

---------------------------------------------------------
Title: New Images of the Solar Corona
Authors: Gurman, Joseph B.; Thompson, Barbara J.; Newmark, Jeffrey A.;
Deforest, Craig E.
1998ASPC..154..329G Altcode: 1998csss...10..329G
In 1.5 years of operation, The Extreme Ultraviolet Imaging Telescope
(EIT) on SOHO has obtained over 40,000 images of the Sun in four
wavebands between 171 Angstroms and 304 Angstroms, with spatial
resolution limited only by the pixel scale of 2.59 arcsec. These
images, and in particular compilations of time series of images into
digital movies, have changed several of our ideas about the corona
at temperatures of 0.9 - 2.5 MK. For the first time, we are able to
see outflow in polar plumes and microjets inputting momentum into the
high-speed, polar wind flow. For the first time, in conjunction with the
LASCO coronagraphs and ground-based He I imagers, we have been able to
see all the structures involved in coronal mass ejections (CMEs), from
the surface of the Sun to 30 solar radii above it. In several cases, we
have been able to observe directly the dramatic Moreton waves emanating
from the active region where the CMEs originate, and radiating across
virtually the entire visible hemisphere of the Sun. We interpret these
large-scale coronal disturbances as fast-mode waves. Such events appear
in the SOHO-LASCO coronagraphs as earthward-directed, and several have
been detected by solar wind monitoring experiments on SOHO and other
spacecraft. We have been able to view a variety of small-scale phenomena
as well, including motions in prominences and filaments, macrospicular
and polar microjet eruptions, and fine structures in the polar crown
filament belt. The multi-wavelength capability of EIT makes it possible
to determine the temperature of the coronal plasma and, here, too,
we have been afforded a novel view: the heating in coronal active
regions occurs over a considerably larger area than the high-density
loops structures alone (i.e., bright features) would indicate.

---------------------------------------------------------
Title: 3-D Modelling of a Filament Observed in Hα and with SOHO/MDI
Authors: Aulanier, G.; Démoulin, P.; van Driel-Gesztelyi, L.; Mein,
P.; Deforest, C.
1998ASPC..155..326A Altcode: 1998sasp.conf..326A
No abstract at ADS

---------------------------------------------------------
Title: Polar plume dynamics: an observational overview
Authors: Deforest, C.
1998ESASP.421...63D Altcode: 1998sjcp.conf...63D
No abstract at ADS

---------------------------------------------------------
Title: Magnetic Flux in Modeled Magnetic Clouds at 1 AU and Some
Specific Comparisons to Associated Photospheric Flux
Authors: Lepping, R. P.; Szabo, A.; DeForest, C. E.; Thompson, B. J.
1997ESASP.415..163L Altcode: 1997cpsh.conf..163L
No abstract at ADS

---------------------------------------------------------
Title: The Structure and Evolution of Solar Coronal Holes Observed
by SOHO During August and September 1996
Authors: Bromage, B. J. I.; del Zanna, G.; Fludra, A.; DeForest, C.;
Thompson, B.
1997ESASP.415..307B Altcode: 1997cpsh.conf..307B
No abstract at ADS

---------------------------------------------------------
Title: Polar Plume Anatomy: Results of a Coordinated Observation
Authors: DeForest, C. E.; Hoeksema, J. T.; Gurman, J. B.; Thompson,
B. J.; Plunkett, S. P.; Howard, R.; Harrison, R. C.; Hasslerz, D. M.
1997SoPh..175..393D Altcode:
On 7 and 8 March 1996, the SOHO spacecraft and several other space-
and ground-based observatories cooperated in the most comprehensive
observation to date of solar polar plumes. Based on simultaneous
data from five instruments, we describe the morphology of the plumes
observed over the south pole of the Sun during the SOHO observing
campaign. Individual plumes have been characterized from the photosphere
to approximately 15 R⊙ yielding a coherent portrait of the features
for more quantitative future studies. The observed plumes arise from
small (∼ 2-5 arc sec diameter) quiescent, unipolar magnetic flux
concentrations, on chromospheric network cell boundaries. They are
denser and cooler than the surrounding coronal hole through which they
extend, and are seen clearly in both Feix and Fexii emission lines,
indicating an ionization temperature between 1.0-1.5 x 106
K. The plumes initially expand rapidly with altitude, to a diameter of
20-30 Mm about 30 Mm off the surface. Above 1.2 R⊙ plumes are observed
in white light (as `coronal rays') and extend to above 12 R⊙. They
grow superradially throughout their observed height, increasing their
subtended solid angle (relative to disk center) by a factor of ∼10
between 1.05 R⊙ and 4-5 R⊙ and by a total factor of 20-40 between
1.05 R⊙ and 12 R⊙. On spatial scales larger than 10 arc sec,
plume structure in the lower corona (R &lt; 1.3 R⊙) is observed to
be steady-state for periods of at least 24 hours; however, on spatial
scales smaller than 10 arc sec, plume XUV intensities vary by 10-20%
(after background subtraction) on a time scale of a few minutes.

---------------------------------------------------------
Title: Time Variability of Polar Plumes as observed with SoHO/EIT
and SoHO/MDI
Authors: Deforest, C. E.; Gurman, J. B.; Moses, J. D.
1997SPD....28.0803D Altcode: 1997BAAS...29..912D
Polar plumes are magnetically open high density structures that are
observed in the polar coronal holes. They arise from unipolar magnetic
footpoints in between chromospheric network cells, and expand as they
rise through the corona to altitudes of at least 15-20 solar radii. On
timescales of hours, plumes are remarkably stable, quiescent structures;
however, we find that plumes vary significantly in XUV intensity
on time scales of a few minutes and length scales of about an arc
minute, based on high cadence observations in the EIT 171A and 195A
passbands. The observed variations propagate outward with speeds of
about 300 km/sec. We demonstrate this effect in several plumes observed
during different EIT high cadence pole observations; compare observed
variations in the photospheric field, as measured simultaneously by
MDI, to the intensity variations in the plumes; and suggest whether
the outward motions represent physical structures or wave motion.

---------------------------------------------------------
Title: Initial Comparison of MDI Photospheric Magnetic Movies and
CDS Transition Region Movies in Quiet Sun
Authors: Tarbell, T.; Brekke, P.; Fludra, A.; Deforest, C.; Saba,
J.; Covington, J.
1997SPD....28.0111T Altcode: 1997BAAS...29..881T
We present simultaneous, coaligned movies of photospheric magnetic
fields and transition region (TR) intensities in very quiet sun near
disk center obtained by SOHO in January, 1997. For example, the 22 Jan
1997 CDS movies show He I 584 (2x10(4) K) and O V 630 (2.4 x 10(5) K)
from 16:51 to 19:54 UT, with a 310 x 240 arcsecond field of view, 105
second cadence, and 1.7 arcsecond pixels. MDI photospheric longitudinal
magnetograms, with 60 second cadence and 0.6 arcsecond pixels, have been
coaligned with these. Bright TR emission correlates more strongly with
close bipoles in the photospheric magnetic field than with magnetic
flux alone. Some strong photospheric flux tubes are barely visible
in the TR emission, appearing only occasionally in connections with
nearby weak opposite polarity fields. Bright transient emissions in
the TR are located at places of cancelling opposite polarities in
photospheric magnetic fields. The flux cancellation continues for tens
of minutes or hours in the magnetic movies. Searches for more rapid
magnetic counterparts to these TR transients and for emerging magnetic
flux regions in the movies are under way. This work was supported by
NASA grant NAG5-3077 at Stanford and Lockheed Martin.

---------------------------------------------------------
Title: Structure and Rotation of the Solar Interior: Initial Results
from the MDI Medium-L Program
Authors: Kosovichev, A. G.; Schou, J.; Scherrer, P. H.; Bogart, R. S.;
Bush, R. I.; Hoeksema, J. T.; Aloise, J.; Bacon, L.; Burnette, A.; de
Forest, C.; Giles, P. M.; Leibrand, K.; Nigam, R.; Rubin, M.; Scott,
K.; Williams, S. D.; Basu, Sarbani; Christensen-Dalsgaard, J.; Dappen,
W.; Rhodes, E. J., Jr.; Duvall, T. L., Jr.; Howe, R.; Thompson, M. J.;
Gough, D. O.; Sekii, T.; Toomre, J.; Tarbell, T. D.; Title, A. M.;
Mathur, D.; Morrison, M.; Saba, J. L. R.; Wolfson, C. J.; Zayer, I.;
Milford, P. N.
1997SoPh..170...43K Altcode:
The medium-l program of the Michelson Doppler Imager instrument on board
SOHO provides continuous observations of oscillation modes of angular
degree, l, from 0 to ∽ 300. The data for the program are partly
processed on board because only about 3% of MDI observations can be
transmitted continuously to the ground. The on-board data processing,
the main component of which is Gaussian-weighted binning, has been
optimized to reduce the negative influence of spatial aliasing of the
high-degree oscillation modes. The data processing is completed in a
data analysis pipeline at the SOI Stanford Support Center to determine
the mean multiplet frequencies and splitting coefficients. The initial
results show that the noise in the medium-l oscillation power spectrum
is substantially lower than in ground-based measurements. This enables
us to detect lower amplitude modes and, thus, to extend the range of
measured mode frequencies. This is important for inferring the Sun's
internal structure and rotation. The MDI observations also reveal the
asymmetry of oscillation spectral lines. The line asymmetries agree
with the theory of mode excitation by acoustic sources localized in the
upper convective boundary layer. The sound-speed profile inferred from
the mean frequencies gives evidence for a sharp variation at the edge
of the energy-generating core. The results also confirm the previous
finding by the GONG (Gough et al., 1996) that, in a thin layer just
beneath the convection zone, helium appears to be less abundant than
predicted by theory. Inverting the multiplet frequency splittings from
MDI, we detect significant rotational shear in this thin layer. This
layer is likely to be the place where the solar dynamo operates. In
order to understand how the Sun works, it is extremely important to
observe the evolution of this transition layer throughout the 11-year
activity cycle.

---------------------------------------------------------
Title: The Solar Minimum X2. 6/1B Flare and CME of 9 July 1996;
Part 1: Solar Data
Authors: Andrews, M. D.; Dryer, M.; Aurass, H.; DeForest, C.;
Kiplinger, A. L.; Meisner, R.; Paswaters, S. E.; Smith, Z.; Tappipn,
S. J.; Thompson, B. J.; Watari, S. I.; Lamy, P.; Mann, G.; Schwenn,
R.; Michels, D. J.; Brueckner, G. E.; Howard, R. A.; Koomen, M.
1997ESASP.404..169A Altcode: 1997cswn.conf..169A
No abstract at ADS

---------------------------------------------------------
Title: Quasi-Periodic Compressive Waves in Polar Plumes
Authors: Deforest, C. E.; Gurman, J. B.
1997ESASP.404..775D Altcode: 1997cswn.conf..775D
No abstract at ADS

---------------------------------------------------------
Title: Solar Magnetic Field Events related to CMEs observed with SOHO
(MDI, EIT, SUMER, LASCO)
Authors: Schmieder, B.; van Driel-Gesztelyi, L.; Wiik, J. E.; Thompson,
B.; de Forest, C.; Saint Cyr, C.; Vial, J. -C.; Nitta, N.; Simnett, G.
1997IAUJD..19E..42S Altcode:
We shall present two CMEs observed by LASCO during the minimum of
activity of the Sun. These are associated with filament disparitions
brusques (DB). CME and DB definitively seem to be consequences of global
magnetic field instability, which causes reconnection of pre-existing
field lines in the corona. We shall demonstrate how cancelling flux
and converging magnetic field in photosphere may destabilize coronal
streamers overlying one or two filament channels.

---------------------------------------------------------
Title: The Solar Minimum X2. 6/1B Flare and CME of 9 July 1996;
Part 2: Propagation
Authors: Dryer, M.; Andrews, M. D.; Aurass, H.; DeForest, C.; Karlicky,
M.; Kiplinger, A.; Klassen, A.; Meisner, R.; Ipavich, F. M.; Galvin,
A. B.; Paswaters, S. E.; Smith, Z.; Tappin, S. J.; Thompson, B. J.;
Watari, S. -I.; Michels, D. J.; Brueckner, G. E.; Howard, R. A.;
Koomen, M. J.; Lamy, P.; Mann, G.; Arzner, K.; Schwenn, R.
1997ESASP.404..331D Altcode: 1997cswn.conf..331D
No abstract at ADS

---------------------------------------------------------
Title: Internal structure and rotation of the Sun: First results
from MDI data
Authors: Kosovichev, A. G.; Schou, J.; Scherrer, P. H.; Bogart, R. S.;
Bush, R. I.; Hoeksema, J. T.; Aloise, J.; Bacon, L.; Burnette, A.;
De Forest, C.; Giles, P. M.; Leibrand, K.; Nigam, R.; Rubin, M.;
Scott, K.; Williams, S. D.; Basu, Sarbani; Christensen-Dalsgaard,
J.; Däppen, W.; Rhodes, E. J., Jr.; Duvall, T. L., Jr.; Howe, R.;
Thompson, M. J.; Gough, D. O.; Sekii, T.; Toomre, J.; Tarbell, T. D.;
Title, A. M.; Mathur, D.; Morrison, M.; Saba, J. L. R.; Wolfson,
C. J.; Zayer, I.; Milford, P. N.
1997IAUS..181..203K Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Prominence Activity Related to CME Observed by SOHO, YOHKOH
and Ground-Based Observatories
Authors: Schmieder, B.; van Driel-Gesztelyi, L.; Wiik, J. E.; Kucera,
T.; Thompson, B.; de Forest, C.; Saint Cyr, C.; Simnett, G. M.
1997ESASP.404..663S Altcode: 1997cswn.conf..663S
No abstract at ADS

---------------------------------------------------------
Title: Time-Distance Helioseismology with the MDI Instrument:
Initial Results
Authors: Duvall, T. L., Jr.; Kosovichev, A. G.; Scherrer, P. H.;
Bogart, R. S.; Bush, R. I.; de Forest, C.; Hoeksema, J. T.; Schou,
J.; Saba, J. L. R.; Tarbell, T. D.; Title, A. M.; Wolfson, C. J.;
Milford, P. N.
1997SoPh..170...63D Altcode:
In time-distance helioseismology, the travel time of acoustic waves
is measured between various points on the solar surface. To some
approximation, the waves can be considered to follow ray paths that
depend only on a mean solar model, with the curvature of the ray
paths being caused by the increasing sound speed with depth below the
surface. The travel time is affected by various inhomogeneities along
the ray path, including flows, temperature inhomogeneities, and magnetic
fields. By measuring a large number of times between different locations
and using an inversion method, it is possible to construct 3-dimensional
maps of the subsurface inhomogeneities. The SOI/MDI experiment on SOHO
has several unique capabilities for time-distance helioseismology. The
great stability of the images observed without benefit of an intervening
atmosphere is quite striking. It has made it possible for us to detect
the travel time for separations of points as small as 2.4 Mm in the
high-resolution mode of MDI (0.6 arc sec pixel-1). This has
enabled the detection of the supergranulation flow. Coupled with the
inversion technique, we can now study the 3-dimensional evolution of
the flows near the solar surface.

---------------------------------------------------------
Title: An Equatorial Coronal Hole at Solar Minimum
Authors: Bromage, B. J. I.; Del Zanna, G.; DeForest, C.; Thompson,
B.; Clegg, J. R.
1997ESASP.404..241B Altcode: 1997cswn.conf..241B
No abstract at ADS

---------------------------------------------------------
Title: Coordinated SOHO Observations of Polar Plumes
Authors: Deforest, C. E.; Scherrer, P. H.; Tarbell, T.; Harrison,
R. A.; Fludra, A.; Delaboudiniere, J. P.; Gurman, J. B.; Wilhelm,
K.; Lemaire, P.; Hassler, D. M.; Kohl, J. L.; Noci, G.; Fineschi,
S.; Brueckner, G. E.; Howard, R. A.; Cyr, O. C. St.
1996AAS...188.4909D Altcode: 1996BAAS...28R.898D
On 7 and 8 March 1996, SOHO instruments engaged in their first
joint science operation, a 12-hr observation of polar plumes
over the South polar coronal hole. The observing mini-campaign
included observations from SOHO, other spacecraft, and ground-based
observatories. Contributing SOHO instruments -- in order of altitude,
MDI, CDS, SUMER, EIT, UVCS, and LASCO -- made overlapping, simultaneous
observations of plume structures from the photosphere out to the
LASCO C3 limit of 32 solar radii. MDI provided line-of-sight surface
magnetograms with a one-min cadence and 0.6 arcsec resolution;
CDS, SUMER, and EIT supplied temperature-sensitive images of the
lower corona with varying cadences and resolutions; UVCS measured
fluctuations in Ly B intensity across the coronal hole with a one-min
cadence at 1.4 R0; and LASCO imaged the entire corona out to 30 R0 in
various visible passbands. Plume footpoints in the lower corona are
observed by EIT and CDS to vary by a factor of two in EUV brightness
with a timescale of tens of minutes, while the structures above are
(as as been previously observed) quiescent on at least a ten-hr time
scale. We present preliminary results of cross-instrument analysis
of the observed plumes, and suggest how this and similar future data
sets can be used to constrain quiet-sun wind acceleration and coronal
heating models for the coronal hole. This research is supported by
the SOI-MDI NASA contract NAG5-3077 at Stanford University. SOHO is
project of international cooperation between NASA and ESA.

---------------------------------------------------------
Title: Initial Results from SOI/MDI High Resolution Magnetograms
Authors: Title, A.; Tarbell, T.; Frank, Z.; Schrijver, C.; Shine,
R.; Wolfson, J.; Zayer, I.; Scherrer, P.; Bush, R.; Deforest, C.;
Hoeksema, T.
1996AAS...188.6915T Altcode: 1996BAAS...28..938T
The Michelson Doppler Imager (MDI) on SoHO takes magnetogram
s with resolutions of 1.2 (high resolution) and 4 (full disk)
arcseconds. Movies of 16 hour duration have been constructed in full
disk and high resolution mode. High resolution movies of the south
polar region also have been obtained. In sums of nine high resolution
magnetograms it is possible to detect fields as low as 5 gauss and
total fluxes as low as 5 10(1) 6 Mx. In mid latitude regions new flux
is observed to emerge everywhere. At all latitudes below 60 degrees
flux is mixed on the scale of supergranulation. In the polar region
above 60 degrees only fields of a single polarity are observed above
the detection limit.

---------------------------------------------------------
Title: SOI/MDI Measurements of Horizontal Flows in the South Polar
Region of the Sun by Correlation Tracking and Doppler Shifts
Authors: Simon, G.; Frank, Z.; Hurlburt, N.; Schrijver, C.; Shine,
R.; Tarbell, T.; Title, A.; Deforest, C.
1996AAS...188.6913S Altcode: 1996BAAS...28R.937S
On 7 March 1996, the SOHO spacecraft was offset from its usual
disk center pointing for an 11-hour observation of the South
Polar region. MDI took a continuous time series of high resolution
longitudinal magnetograms during this period, in support of the
SOHO-wide Joint Observing Program on polar plumes. It also ran several
hours each of two other programs: one to map the horizontal flows near
the pole by correlation tracking and Doppler shifts, and another to
study wave propagation (e.g., by time-distance helioseismology) at
these high latitudes. In this poster we present preliminary results
from the first program. Both techniques yield measurements of the
differential rotation profile near the pole and of horizontal flows of
supergranulation. These results are compared with each other and with
corresponding measurements in low latitudes. The location of magnetic
features in the horizontal flows is also shown. The SOI/MDI program
is supported by NASA grant NAG5-3077.

---------------------------------------------------------
Title: Multi-Spectral Solar Telescope Array IX: quantitative
measurements of the solar corona
Authors: DeForest, Craig E.; Walker, Arthur B.; Allen, Maxwell J.;
Hoover, Richard B.; Barbee, Troy W.
1995SPIE.2515..273D Altcode:
The Multi-Spectral Solar Telescope Array (MSSTA) is a rocket borne
cluster of normal- incidence multilayer coated telescopes for the
high-resolution study of the solar atmosphere and corona. In previous
papers, we have described the design, calibration, and flight of the
MSSTA, and reported qualitative results of those solar observations. In
the present paper, we describe the MSSTA's measured quantitative
instrument response to the optically thin solar coronal plasma, and
present an example of the derivation of solar temperature and density
diagnostic information from four photographic images obtained during
the instrument's successful inaugural flight in 1991.

---------------------------------------------------------
Title: Design and performance of thin foil XUV filters for the
Multi-Spectral Solar Telescope Array II
Authors: Plummer, James E.; DeForest, Craig E.; Martinez-Galarce,
Dennis S.; Kankelborg, Charles C.; Gore, David B.; O'Neal, Ray H.;
Walker, Arthur B.; Powell, Forbes R.; Hoover, Richard B.; Barbee,
Troy W.; Weed, J. W.
1995SPIE.2515..565P Altcode:
The redesigned payload of the Multi-Spectral Solar Telescope Array
(MSSTA), the MSSTA II, was successfully flown on November 3, 1994. The
multilayer mirrors used in the normal incidence optical systems of the
MSSTA II are efficient reflectors for soft x-ray/extreme ultraviolet
(EUV) radiation at wavelengths that satisfy the Bragg condition,
thus allowing a narrow band of the soft x-ray/EUV spectrum to be
isolated. When applied to solar observations the temperature response
of an optical system is quite sensitive to telescope bandpass because
of the high density of lines in the coronal spectrum. We have designed
a set of thin foil filters in conjunction with our multilayer optics to
eliminate contaminant lines and specular reflectivity, thus enhancing
the temperature diagnostic capabilities of our instruments. Extensive
measurements have recently been carried out on the thin foil filters
at the Stanford Synchrotron Radiation Laboratory. We describe here the
design and performance of thin foil filters developed for the MSSTA II.

---------------------------------------------------------
Title: Multi-Spectral Solar Telescope Array VIII: the second flight
Authors: Walker, Arthur B.; Allen, Maxwell J.; DeForest, Craig E.;
Kankelborg, Charles C.; Martinez-Galarce, Dennis S.; Plummer, James
E.; Hoover, Richard B.; Barbee, Troy W.; Gore, David B.
1995SPIE.2515..182W Altcode:
The Multi Spectral Solar Telescope Array (MSSTA) is a rocket borne
observatory that utilizes an array of multi-layer and interference film
coated telescopes to observe the solar atmosphere from the chromosphere
to the corona, over a broad spectral range (VUV - soft x rays). The
MSSTA is continuously evolved to incorporate new instruments, and
to improve its ability to investigate specific topics related to
the structure and dynamics of the solar atmosphere. We describe
chromospheric and coronal observations recorded during the second
flight of the MSSTA on November 3, 1994 at 1915 UT.

---------------------------------------------------------
Title: Calibration of multilayer mirrors for the Multi-Spectral
Solar Telescope Array II
Authors: Kankelborg, Charles C.; Plummer, James E.; Martinez-Galarce,
Dennis S.; O'Neal, Ray H.; DeForest, Craig E.; Walker, Arthur B.;
Barbee, Troy W.; Weed, J. W.; Hoover, Richard B.; Powell, Forbes R.
1995SPIE.2515..436K Altcode:
The Multi-Spectral Solar Telescope Array II (MSSTA II), a rocket-borne
solar observatory, was successfully flown on November 3, 1994 obtaining
solar images in multiple XUV and FUV bands with an array of compact
multilayer telescopes. Extensive measurements have recently been carried
out on some of the multilayer telescopes at the Stanford Synchrotron
Radiation Laboratory. These measurements are the first high spectral
resolution calibrations of newly introduced MSSTA II instruments and
instruments with lambda0 less than 130 angstrom. Previous
measurements and/or calculations of telescope throughputs have been
confirmed with greater accuracy. Results are presented on Mo/Si
multilayer bandpasses, and multilayer bandpass changes with time.

---------------------------------------------------------
Title: Multi-Spectral Observation and Modeling of Polar Plumes in
the Solar Corona
Authors: Deforest, C. E.; Walker, A. B. C., Jr.; Hoover, R. B.;
Barbee, T. W., Jr.
1995SPD....26..604D Altcode: 1995BAAS...27..961D
No abstract at ADS

---------------------------------------------------------
Title: High-Resolution Multi-Spectral Observations of Solar Coronal
Open Structures: Polar and Equatorial Plumes and Rays.
Authors: Deforest, Craig Edward
1995PhDT........10D Altcode:
XUV emissions from the lower corona (R ~1.5 R odot) have been observed
by the Multi-Spectral Solar Telescope Array (MSSTA), a cluster of
normal-incidence XUV telescopes that flew in 1991 and 1994, and by the
MSSTA's predecessor, the Stanford/MSFC/LLNL Rocket Spectroheliograph,
in 1987. In 1987 and 1994, observations of the Sun at 173 A and
comparison with concurrent magnetogram images, show narrow ( ~10 arc
sec), radially expanding polar plumes with unipolar footpoints in the
polar coronal holes. The 1991 observation, taken near solar maximum,
does not show these features over the poles of the Sun, though plume
-like footpoints are observed. The 1991 observation does show another
class of plume, "Equatorial plumes", that have narrow (~10 arc sec)
footpoints which appear to be unipolar, and that expand super-radially
with a solid angle expansion factor of ~25 at R = 2 R odot. In this
dissertation, I provide a brief overview of some previous observations
and of our instruments (Chap. I), describe the MSSTA instruments'
theoretical response to the coronal plasma (Chap. II), and present
quantitative results of these observations (Chaps. III and IV). A brace
of appendices describe some details of the MSSTA film calibration, and
illustrate the filter design process that was used for the 1994 flight.

---------------------------------------------------------
Title: High-resolution multi-spectral observations of solar coronal
open structures: Polar and equatorial plumes and rays
Authors: DeForest, Craig Edward
1995PhDT.......173D Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Performance of the multilayer-coated mirrors for the
MultiSpectral Solar Telescope Array
Authors: Allen, Maxwell J.; Willis, Thomas D.; Kankelborg, Charles
C.; O'Neal, Ray H.; Martinez-Galarce, Dennis S.; Deforest, Craig
E.; Jackson, Lisa R.; Plummer, James D.; Walker, Arthur B.; Barbee,
Troy W.; Weed, J. W.; Hoover, Richard B.
1994SPIE.2011..381A Altcode:
The Multi-Spectral Solar Telescope Array, a rocket-borne solar
observatory, was successfully flown in May, 1991, obtaining solar images
in eight XUV and FUV bands with 12 compact multilayer telescopes. We
report on recent measurements of the performance of multilayer coated
mirrors for the Multi Spectral Solar Telescope Array, carried out at
the Stanford Synchrotron Radiation Laboratory.

---------------------------------------------------------
Title: X-ray/EUV/FUV calibration of photographic films for solar
research
Authors: Hoover, Richard B.; Walker, Arthur B.; Deforest, Craig E.;
Allen, Maxwell J.; Gore, David B.
1994SPIE.2011..504H Altcode:
Film was chosen as the detector for the Multi-Spectral Solar Telescope
Array (MSSTA), a sub-orbital solar observatory designed to operate over
the entire soft x-ray, extreme ultraviolet (EUV), and far ultraviolet
(FUV) spectral regime. In order to accurately calibrate the solar images
obtained on the initial May 13, 1991 MSSTA flight, and to optimize the
film loads for the diverse telescopes being developed for the MSSTA
re-flight, we performed extensive calibrations at the NIST SURF II and
the Stanford Synchrotron Radiation Laboratory synchrotrons. In addition
to detailed studies of the MSSTA flight films (XUV-100 and 649),
we also measured the performance characteristics of Kodak Technical
Pan 2415 film, and the Agfa 10E56, 10E75 and Ilford HOTEC holographic
emulsions. These measurements yielded valuable information concerning
the soft x-ray/EUV/FUV response of the films and provided important
insights into the physical properties of the films and their behavior
after prolonged exposure to high vacuum.

---------------------------------------------------------
Title: Thermal and Density Structure of Polar Plumes
Authors: Walker, A. B. C., Jr.; Deforest, C. E.; Hoover, R. B.;
Barbee, T. W., Jr.
1993SoPh..148..239W Altcode:
Normal incidence multilayer coated EUV/XUV optical systems provide
a powerful technique for the study of the structure of the solar
corona. Such systems permit the imaging of the full solar disk and
corona with high angular resolution in narrow wavelength bands that
are dominated by a single line or a line multiplet excited over a
well defined range of temperatures. We have photometrically analysed,
and derived temperature and density information from, images of polar
plumes obtained with a multilayer Cassegrain telescope operating in
the wavelength interval λ = 171 to 175 å, which is dominated by
FeIX and FeX emission. This observation was obtained in October 1987,
and is the first high resolution observation of an astronomical object
obtained with normal incidence multilayer optics techniques. We find
that photometric data taken from this observation, applied to a simple,
semi-empirical model of supersonic solar wind flow, are consistent with
the idea that polar plumes are a source of the solar wind. However, we
are not able to uniquely trace high speed streams to polar plumes. The
temperatures that we observed are typically ∼ 1 500 000 K for both
the plumes and the interplume regions, with the plume temperatures
slightly higher than those of the surrounding atmosphere. Typical
electron densities of the plume and interplume regions, respectively,
are 5 × 109 cm−3 and 1 × 108
cm−3 at the limb of the Sun.

---------------------------------------------------------
Title: Thermal and Density Structure of Polar Polumes II: Analysis
of the Transition to the Solar Wind, using EUV and Visible Light
Observations
Authors: Deforest, C. E.; Walker, A. B. C., Jr.; Sime, D.; Hoover,
R. B.; Barbee, T. W., Jr.
1993BAAS...25.1203D Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Ultrahigh-resolution photographic films for x-ray/EUV/FUV
astronomy
Authors: Hoover, Richard B.; Walker, Arthur B. C., Jr.; Deforest,
Craig E.; Watts, Richard; Tarrio, Charles
1993SPIE.1742..549H Altcode:
The quest for ultrahigh resolution full-disk images of the Sun
at soft x-ray/EUV/FUV wavelengths has increased the demand for
photographic films with broad spectral sensitivity, high spatial
resolution, and wide dynamic range. These requirements were made
more stringent by the recent development of multilayer telescopes
and coronagraphs capable of operating at normal incidence at soft
x-ray/EUV wavelengths. Photographic films are the only detectors now
available with the information storage capacity and dynamic range
such as is required for recording images of the solar disk and corona
simultaneously witharc second spatial resolution. During the
Stanford/MSFC/LLNL Rocket X-Ray Spectroheliograph and Multi-Spectral
Solar Telescope Array (MSSTA) programs, we utilized photographic
films to obtain high resolution full-disk images of the Sun at
selected soft x-ray/EUV/FUV wavelengths. In order to calibrate our
instrumentation for quantitative analysis of our solar data and to
select the best emulsions and processing conditions for the MSSTA
reflight, we recently tested several photographic films. These studies
were carried out at the NIST SURF II synchrotron and the Stanford
Synchrotron Radiation Laboratory. In this paper, we provide the results
of those investigations.

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Title: Calibration of the multispectral solar telescope array
multilayer mirrors and XUV filters
Authors: Allen, Maxwell J.; Willis, Thomas D.; Kankelborg, Charles
C.; O'Neal, Ray H.; Martinez-Galarce, Dennis S.; Deforest, Craig E.;
Jackson, Lisa R.; Lindblom, Joakim F.; Walker, Arthur B.; Barbee,
Troy W., Jr.; Weed, J. W.; Hoover, Richard B.; Powell, Forbes R.
1993SPIE.1742..562A Altcode:
The Multi-Spectral Solar Telescope Array (MSSTA), rocket-borne
solar observatory, was successfully flown in May, 1991, obtaining
solar images in eight XUV and FUV bands with 12 compact multilayer
telescopes. Extensive measurements have recently been carried out on the
multilayer telescopes and thin film filters at the Stanford Synchrotron
Radiation Laboratory. These measurements are the first high spectral
resolution calibrations of the MSSTA instruments. Previous measurements
and/or calculations of telescope throughputs have been confirmed with
greater accuracy. Results are presented on Mo/Si multilayer bandpass
changes with time and experimental potassium bromide and tellurium
filters.

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Title: The density structure of polar plumes.
Authors: Walker, A. B. C., Jr.; Deforest, C. E.; Barbee, T. W., Jr.;
Hoover, R. B.
1992BAAS...24.1073W Altcode:
No abstract at ADS

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Title: Solar observations with the Multi-Spectral Solar Telescope
Array
Authors: Hoover, Richard B.; Walker, Arthur B. C., Jr.; Lindblom,
Joakim; Allen, Maxwell; O'Neal, Ray; Deforest, Craig; Barbee, Troy
W., Jr.
1992SPIE.1546..175H Altcode:
The Multi-Spectral Solar Telescope Array (MSSTA) is a sounding
rocket-borne solar observatory which was succesfully launched on May 13,
1991, from the White Sands Missile Range, NM. Ultrahigh resolution,
full-disk solar X-ray, EUV, and FUV images were obtained with the
MSSTA Herschelian, Cassegrain, and Ritchey-Chretien telescopes. We
describe the payload and provide some preliminary scientific results
from the flight.

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Title: The Multi-Spectral Solar Telescope Array. II - Soft X-ray/EUV
reflectivity of the multilayer mirrors
Authors: Barbee, Troy W., Jr.; Weed, J. W.; Hoover, Richard B. C., Jr.;
Allen, Max J.; Lindblom, Joakim F.; O'Neal, Ray H.; Kankelborg, Charles
C.; Deforest, Craig E.; Paris, Elizabeth S.; Walker, Arthur B. C.
1992SPIE.1546..432B Altcode: 1992SPIE.2011..432B
We have developed seven compact soft X-ray/EUV (XUV) multilayer
coated and two compact FUV interference film coated Cassegrain and
Ritchey-Chretien telescopes for a rocket borne observatory, the
Multi-Spectral Solar Telescope Array. We report here on extensive
measurements of the efficiency and spectral bandpass of the XUV
telescopes carried out at the Stanford Synchrotron Radiation Laboratory.

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Title: Photographic films for the Multi-Spectral Solar Telescope Array
Authors: Hoover, Richard B.; Walker, Arthur B. C., Jr.; Deforest,
Craig E.; Allen, Maxwell J.; Lindblom, Joakim F.; Gilliam, Lou;
November, Larry; Brown, Todd; Dewan, Clyde A.
1992SPIE.1546..188H Altcode: 1992SPIE.2011..188H
The rocketborne Multi-Spectral Solar Telescope Array (MSSTA) uses an
array of Ritchey-Chretien, Cassegrain, and Herschelian telescopes to
produce ultrahigh-resolution full-disk images of the sun within the soft
X-ray, EUV, and FUV ranges. Such imaging of the solar disk and corona
out to several solar radii placed great demands on the MSSTA's data
storage capabilities; in addition, its photographic films required
very low outgassing rates. Results are presented from calibration
tests conducted on the MSSTA's emulsions, based on measurements at
NIST's synchrotron facility.

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Title: Performance of the Multi-Spectral Solar Telescope
Array. Pt. 3. Optical characteristics of the Ritchey-Chrétien and
Cassegrain telescopes.
Authors: Hoover, Richard B.; Baker, Phillip C.; Hadaway, James B.;
Johnson, R. B.; Peterson, Cynthia; Gabardi, David R.; Walker, Arthur
B., Jr.; Lindblom, J. F.; Deforest, Craig; O'Neal, R. H.
1991SPIE.1343..189H Altcode:
The Multi-Spectral Solar Telescope Array (MSSTA) is a sounding rocket
borne observatory for investigations of the Sun in the soft X-ray/EUV
and FUV regimes of the electromagnetic spectrum. At soft X-ray
wavelengths (λλ &lt; 100 Å), the MSSTA utilizes single reflection
multilayer coated Herschelian telescopes. For selected wavelengths
in the EUV (100 - 1000 Å) the MSSTA employs five doubly reflecting,
multilayer coated Ritchey-Chrétien and two Cassegrain telescopes. In
the FUV (λλ &gt; 1000 Å) the MSSTA utilizes two Ritchey-Chrétien
telescopes, with optics coated with thin film interference coatings. The
authors describe the interferometric alignment, testing, focusing,
visible light testing, and optical performance characteristics of the
Ritchey-Chrétien and Cassegrain telescopes.

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Title: Multi-spectral solar telescope array. V. Temperature diagnostic
response to the optically thin solar plasma.
Authors: Deforest, C. E.; Krankelborg, C. C.; Allen, M. J.; Paris,
E. S.; Willis, T. D.; Lindblom, J. F.; O'Neal, R. H.; Walker, A. B. C.,
Jr.; Barbee, T. W., Jr.; Hoover, R. B.; Barbee, T. W., III
1991OptEn..30.1125D Altcode:
The authors have developed compact soft X-ray, extreme ultraviolet
(EUV), and far-ultraviolet multilayer coated telescopes for the
study of the solar chromosphere, corona, and corona/solar wind
interface. In addition to permitting traditional normal incidence
optical configurations to be used at soft X-ray/EUV wavelengths,
multilayer coatings also allow a narrow wavelength band (λ/Δλ ≡
15 - 100) to be selected for imaging. The resulting telescopes provide
a very powerful and flexible diagnostic instrument for the study of
both the fine-scale structure of the chromosphere/corona interface
and the large-scale structure of the corona and corona/solar wind
interface. The authors report on the ability of the MSSTA payload to
obtain temperature diagnostic information about the optically thin
solar plasma. They also discuss applications of this information to
studies of coronal structure.

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Title: EUV/FUV response characteristics of photographic films for
the multi-spectral solar telescope array.
Authors: Hoover, Richard B.; Walker, Arthur B. C., Jr.; Deforest,
Craig E.; Allen, Maxwell J.; Lindblom, Joakim F.
1991OptEn..30.1116H Altcode:
The Multi-Spectral Solar Telescope Array (MSSTA) is a sounding
rocket-borne observatory designed to produce ultrahigh-resolution
full-disk images of the sun. The desire for ultrahigh-resolution
(≡0.1 to 0.3″ images of the solar disk and corona out to 1.5
Rsun demands an information storage capacity that
at the present time can be met only by the highest quality photographic
emulsions. The authors describe the performance and characteristics
required of the MSSTA photographic films for solar observations in the
soft X-ray/EUV and FUV wavelength regimes. They discuss the properties
of the important new emulsions selected for flight.

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Title: Multi-spectral solar telescope array II: Soft X-ray/EUV
reflectivity of the multilayer mirrors.
Authors: Barbee, T. W., Jr.; Weed, J. W.; Hoover, R. B.; Allen,
M. J.; Lindblom, J. F.; O'Neal, R. H.; Kankelborg, C. C.; Deforest,
C. E.; Paris, E. S.; Walker, A. B. C., Jr.; Willis, T. D.; Gluskin,
E.; Pianetta, P.; Baker, P. C.
1991OptEn..30.1067B Altcode:
The authors have developed seven compact soft X-ray/EUV (XUV)
multilayer-coated and two compact FUV interference-film-coated
Cassegrain and Ritchey-Chrétien telescopes for a rocket-borne
observatory, the Multi-Spectral Solar Telescope Array. They report on
extensive measurements of the efficiency and spectral bandpass of the
XUV telescopes.

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Title: The Density Structure of Polar Plumes
Authors: Walker, A. B. C., Jr.; Lindblom, J. F.; Deforest, C. E.;
Paris, E. S.; Allen, M. J.; Hoover, R. B.; Barbee, T. W., Jr.
1991BAAS...23.1264W Altcode:
No abstract at ADS

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Title: The Ultra High Resolution XUV
Spectroheliograph. Pt. 2. Predicted performance.
Authors: Walker, A. B. C., Jr.; Lindblom, J. F.; Timothy, J. G.;
Allen, M. J.; Deforest, C. E.; Kankelborg, C.; O'Neal, R. H.; Paris,
E. S.; Willis, T.; Barbee, T. W., Jr.; Hoover, R. B.
1991SPIE.1343..319W Altcode:
The authors have developed an Ultra High Resolution XUV
Spectroheliograph (UHRXS) for flight among the initial scientific
instruments to be placed on the Space Station "Freedom". The principal
UHRXS instruments are nine multilayer Ritchey-Chrétien telescopes
covering the spectral range from ≡70 Å to ≡300 Å. The XUV images
will be recorded on high resolution photographic film, allowing angular
resolutions as high as 0.1″to be achieved for a 1.0° field. The
authors present an analysis of the expected sensitivity and resolving
power of the UHRXS telescopes, and the diagnostic response of the
various UHRXS instruments to structures in the solar atmosphere between
10,000K and 100,000,000K.

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Title: Performance of the Multi-Spectral Solar Telescope Array VI:
performance and characteristics of the photographic films
Authors: Hoover, Richard B.; Walker, Arthur B.; Deforest, Craig E.;
Allen, Maxwell J.; Lindblom, Joakim F.
1991SPIE.1343..175H Altcode:
No abstract at ADS

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Title: Performance of the Multi-Spectral Solar Telescope Array V:
temperature diagnostic response to the optically thin solar plasma
Authors: Deforest, Craig E.; Kankelborg, Charles C.; Allen, Maxwell
J.; Paris, Elizabeth S.; Willis, Thomas D.; Lindblom, Joakim F.;
O'Neal, Ray H.; Walker, Arthur B.; Barbee, Troy W.; Hoover, Richard
B.; Barbee, Troy W.; Gluskin, Efim S.
1991SPIE.1343..404D Altcode:
No abstract at ADS

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Title: Performance of compact multilayer coated telescopes at soft
x-ray/EUV and far-ultraviolet wavelengths I
Authors: Hoover, Richard B.; Barbee, Troy W.; Baker, Phillip C.;
Lindblom, Joakim F.; Allen, Maxwell J.; Deforest, Craig E.; Kankelborg,
Charles C.; O'Neal, Ray H.; Paris, Elizabeth S.; Walker, Arthur B.
1990SPIE.1235..821H Altcode:
No abstract at ADS

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Title: Multi-Spectral Solar Telescope Array
Authors: Walker, A. B. C., Jr.; Allen, M. J.; Deforest, C.; Kankelborg,
C.; Lindblom, J. F.; O'Neal, R. H.; Paris, E.; Hoover, R. B.; Barbee,
T. W., Jr.
1990BAAS...22..808W Altcode:
No abstract at ADS