Author name code: fisher ADS astronomy entries on 2022-09-14 author:"Fisher, George H." ------------------------------------------------------------------------ Title: Boundary Data-driven MHD Simulation of the Eruptions of Active Region 11158 Authors: Fan, Yuhong; Fisher, George; Afanasev, Andrei; Kazachenko, Maria Bibcode: 2022cosp...44.2476F Altcode: We present data-driven MHD simulation of the evolution of Active Region (AR) 11158, using lower boundary driving electric fields inferred from the time sequence of vector magnetograms observed by the SDO/HMI. The lower boundary is driven with the horizontal component of the PDFI electric field (Fisher et al. 2020), and an additional twisting electric field derived based on the vertical electric current measured from the vector magnetograms. Our simulation shows the build-up of a coronal magnetic field with significant free magnetic energy and strongly sheared, sigmoid shaped loops above the PIL of the central delta-sunspot, showing morphology similar to that observed. The simulation also shows the development of a set of homologous eruptions. We discuss the structure of the 3D coronal magnetic field and the mechanisms for the onset of the eruptions. Title: How could we use observations to constrain and validate data-driven models of solar eruptions? Authors: Kazachenko, Maria; Fan, Yuhong; Fisher, George; Cheung, Mark; Afanasev, Andrei; Tremblay, Benoit; Kazachenko, Maria Bibcode: 2022cosp...44.2464K Altcode: Observations of vector magnetic fields, coronal loops, flare ribbons and coronal dimmings provide observational constraints for data-constrained and data-driven models of solar eruptions. In this talk I will review specific observational properties that we could use to evaluate the realism of these models: photospheric energy fluxes, reconnection fluxes, inferred flux rope properties and future coronal field measurements. I will also discuss possible ways to improve current models using more realistic photospheric boundary conditions. Title: Data-driven, time-dependent modeling of pre-eruptive coronal magnetic field configuration at the periphery of NOAA AR 11726 Authors: Lumme, E.; Pomoell, J.; Price, D. J.; Kilpua, E. K. J.; Kazachenko, M. D.; Fisher, G. H.; Welsch, B. T. Bibcode: 2022A&A...658A.200L Altcode: Context. Data-driven, time-dependent magnetofrictional modeling has proved to be an efficient tool for studying the pre-eruptive build-up of energy for solar eruptions, and sometimes even the ejection of coronal flux ropes during eruptions. However, previous modeling works have illustrated the sensitivity of the results on the data-driven boundary condition, as well as the difficulty in modeling the ejections with proper time scales.
Aims: We aim to study the pre- and post-eruptive evolution of a weak coronal mass ejection producing eruption at the periphery of isolated NOAA active region (AR) 11726 using a data-driven, time-dependent magnetofrictional simulation, and aim to illustrate the strengths and weaknesses of our simulation approach.
Methods: We used state-of-the-art data processing and electric field inversion methods to provide the data-driven boundary condition for the simulation. We analyzed the field-line evolution, magnetic connectivity, twist, as well as the energy and helicity budgets in the simulation to study the pre- and post-eruptive magnetic field evolution of the observed eruption from AR11726.
Results: We find the simulation to produce a pre-eruptive flux rope system consistent with several features in the extreme ultraviolet and X-ray observations of the eruption, but the simulation largely fails to reproduce the ejection of the flux rope. We find the flux rope formation to be likely driven by the photospheric vorticity at one of the footpoints, although reconnection at a coronal null-point may also feed poloidal flux to the flux rope. The accurate determination of the non-inductive (curl-free) component of the photospheric electric field boundary condition is found to be essential for producing the flux rope in the simulation.
Conclusions: Our results illustrate the applicability of the data-driven, time-dependent magnetofrictional simulations in modeling the pre-eruptive evolution and formation process of a flux rope system, but they indicate that the modeling output becomes problematic for the post-eruptive times. For the studied event, the flux rope also constituted only a small part of the related active region.

Movies are available at https://www.aanda.org Title: Boundary Data-driven MHD Simulations of the Emergence and Eruption of Active Region 11158 Authors: Fan, Yuhong; Kazachenko, Maria; Afanasev, Andrei; Fisher, George Bibcode: 2021AGUFMSH44A..02F Altcode: We present data-driven MHD simulations of the emergence and eruption of Active Region (AR) 11158, using a lower boundary driving electric field inferred from the time sequence of vector magnetograms observed by the SDO/HMI with the PDFI-SS inversion method (developed by Fisher et al. 2020), and an additional driving electric field that represents sunspot rotation and shearing at the polarity inversion line (PIL). We found that highly sheared, S-shaped sigmoid loops form above the PIL of the central delta-sunspot, showing morphology similar to the observation. We experiment with the additional electric field that drives the sunspot rotation and shearing at the PIL and examine the conditions for the development of the eruptive flares. Title: Validation of the PDFI_SS Method for Electric Field Inversions Using a Magnetic Flux Emergence Simulation Authors: Afanasyev, Andrey N.; Kazachenko, Maria D.; Fan, Yuhong; Fisher, George H.; Tremblay, Benoit Bibcode: 2021ApJ...919....7A Altcode: 2021arXiv210610579A Knowledge of electric fields in the photosphere is required to calculate the electromagnetic energy flux through the photosphere and set up boundary conditions for data-driven magnetohydrodynamic (MHD) simulations of solar eruptions. Recently, the PDFI_SS method for inversions of electric fields from a sequence of vector magnetograms and Doppler velocity measurements was improved to incorporate spherical geometry and a staggered-grid description of variables. The method was previously validated using synthetic data from anelastic MHD (ANMHD) simulations. In this paper, we further validate the PDFI_SS method, using approximately 1 hr long MHD simulation data of magnetic flux emergence from the upper convection zone into the solar atmosphere. We reconstruct photospheric electric fields and calculate the Poynting flux, and we compare those to the actual values from the simulations. We find that the accuracy of the PDFI_SS reconstruction is quite good during the emergence phase of the simulated ephemeral active region evolution and decreases during the shearing phase. Analyzing our results, we conclude that the more complex nature of the evolution (compared to the previously studied ANMHD case) that includes the shearing evolution phase is responsible for the obtained accuracy decrease. Title: Boundary data-driven MHD simulations of the evolution of AR 11158 Authors: Fan, Y.; Kazachenko, M.; Afanasev, A.; Fisher, G. Bibcode: 2021AAS...23831320F Altcode: We have performed initial data-driven MHD simulations of the emergence and evolution of Active Region (AR) 11158, using a lower boundary driving electric field inferred from the time sequence of vector magnetograms observed by the SDO/HMI with the PDFI-SS inversion method (developed by Fisher et al. 2020), and an additional driving electric field that represents sunspot rotation and shearing at the polarity inversion line (PIL). We found that highly sheared, S-shaped sigmoid loops form above the PIL of the central delta-sunspot, showing morphology similar to that seen in the SDO/AIA observations. We experiment with the additional electric field that drives the sunspot rotation and shearing at the PIL and examine the conditions for the development of the eruptive flares.

Acknowledgement: This work is supported in part by the NASA LWS grant 80NSSC19K0070 to NCAR. Title: Coupling a Global Heliospheric Magnetohydrodynamic Model to a Magnetofrictional Model of the Low Corona Authors: Hayashi, Keiji; Abbett, William P.; Cheung, Mark C. M.; Fisher, George H. Bibcode: 2021ApJS..254....1H Altcode: Recent efforts coupling our Sun-to-Earth magnetohydrodynamics (MHD) model and lower-corona magnetofrictional (MF) model are described. Our Global Heliospheric MHD (GHM) model uses time-dependent three-component magnetic field data from the lower-corona MF model as time-dependent boundary values. The MF model uses data-assimilation techniques to introduce the vector magnetic field data from the Solar Dynamics Observatory/Helioseismic and Magnetic Imager, hence as a whole this simulation coupling structure is driven with actual observations. The GHM model employs a newly developed interface boundary treatment that is based on the concept of characteristics, and it properly treats the interface boundary sphere set at a height of the sub-Alfvénic lower corona (1.15 R⊙ in this work). The coupled model framework numerically produces twisted nonpotential magnetic features and consequent eruption events in the solar corona in response to the time-dependent boundary values. The combination of our two originally independently developed models presented here is a model framework toward achieving further capabilities of modeling the nonlinear time-dependent nature of magnetic field and plasma, from small-scale solar active regions to large-scale solar wind structures. This work is a part of the Coronal Global Evolutionary Model project for enhancing our understanding of Sun-Earth physics to help improve space weather capabilities. Title: The Coronal Global Evolutionary Model: Using HMI Vector Magnetogram and Doppler Data to Determine Coronal Magnetic Field Evolution Authors: Kazachenko, Maria; Abbett, Bill; Liu, Yang; Fisher, George; Welsch, Brian; Bercik, Dave; DeRosa, Marc; Cheung, Mark; Sun, Xudong; Hoeksema, J. Todd; Erkka Lumme, .; Hayashi, Keiji; Lynch, Benjamin Bibcode: 2021cosp...43E1785K Altcode: The Coronal Global Evolutionary Model (CGEM) provides data-driven simulations of the magnetic field in the solar corona to better understand the build-up of magnetic energy that leads to eruptive events. The CGEM project has developed six capabilities. CGEM modules (1) prepare time series of full-disk vector magnetic field observations to (2) derive the changing electric field in the solar photosphere over active-region scales. This local electric field is (3) incorporated into a surface flux transport model that reconstructs a global electric field that evolves magnetic flux in a consistent way. These electric fields drive a (4) 3D spherical magnetofrictional (SMF) model, either at high resolution over a restricted range of solid angles or at lower resolution over a global domain to determine the magnetic field and current density in the low corona. An SMF-generated initial field above an active region and the evolving electric field at the photosphere are used to drive (5) detailed magnetohydrodynamic (MHD) simulations of active regions in the low corona. SMF or MHD solutions are then used to compute emissivity proxies that can be compared with coronal observations. Finally, a lower-resolution SMF magnetic field is used to initialize (6) a global MHD model that is driven by an SMF electric field time series to simulate the outer corona and heliosphere, ultimately connecting Sun to Earth. As a demonstration, this report features results of CGEM applied to observations of the evolution of NOAA Active Region 11158 in 2011 February. Title: Solar and Heliospheric Models at the CCMC - An Update Authors: MacNeice, P. J.; Chulaki, A.; Mendoza, A. M. M.; Mays, M. L.; Weigand, C.; Arge, C. N.; Jones, S. I.; Linker, J.; Downs, C.; Torok, T.; Fisher, G. H.; Cheung, C. M. M. Bibcode: 2020AGUFMSH0030015M Altcode: The Community Coordinated Modeling Center (CCMC) at NASA Goddard Space Flight Center is the world largest repository of models dedicated to Space Weather Research and forecasting. In this presentation we provide an update on new additions and updates to the CCMC's inventory of Solar and Heliospheric models. In particular, we describe the latest version of WSA, the CORHEL TDM model, and the CGEM model suite. The latest version of WSA is now available to users through our Runs-On-Request websites as well as through its continuous near realtime execution. It can use input magnetograms from an extensive list of observatories, including maps processed using the ADAPT surface flux evolution model, and can return results and solar wind forecasts at all inner planets and most inner heliospheric spacecraft locations. The CORHEL TDM model enables users to design flux ropes embedded in coronal fields in derived from observed magnetograms, and then follow the evolution of the flux rope using a zero-beta MHD code. A future upgrade (currently in development at PredSci) w ill support full thermodynamic CME simulations. Finally, the CGEM model suite supports the generation and application of boundary conditions for realistic driving of coronal 3D field models based on times series observations of photospheric vector magnetogram data. Title: The Coronal Global Evolutionary Model: Using HMI Vector Magnetogram and Doppler Data to Determine Coronal Magnetic Field Evolution Authors: Hoeksema, J. Todd; Abbett, William P.; Bercik, David J.; Cheung, Mark C. M.; DeRosa, Marc L.; Fisher, George H.; Hayashi, Keiji; Kazachenko, Maria D.; Liu, Yang; Lumme, Erkka; Lynch, Benjamin J.; Sun, Xudong; Welsch, Brian T. Bibcode: 2020ApJS..250...28H Altcode: 2020arXiv200614579H The Coronal Global Evolutionary Model (CGEM) provides data-driven simulations of the magnetic field in the solar corona to better understand the build-up of magnetic energy that leads to eruptive events. The CGEM project has developed six capabilities. CGEM modules (1) prepare time series of full-disk vector magnetic field observations to (2) derive the changing electric field in the solar photosphere over active-region scales. This local electric field is (3) incorporated into a surface flux transport model that reconstructs a global electric field that evolves magnetic flux in a consistent way. These electric fields drive a (4) 3D spherical magnetofrictional (SMF) model, either at high resolution over a restricted range of solid angles or at lower resolution over a global domain to determine the magnetic field and current density in the low corona. An SMF-generated initial field above an active region and the evolving electric field at the photosphere are used to drive (5) detailed magnetohydrodynamic (MHD) simulations of active regions in the low corona. SMF or MHD solutions are then used to compute emissivity proxies that can be compared with coronal observations. Finally, a lower-resolution SMF magnetic field is used to initialize (6) a global MHD model that is driven by an SMF electric field time series to simulate the outer corona and heliosphere, ultimately connecting Sun to Earth. As a demonstration, this report features results of CGEM applied to observations of the evolution of NOAA Active Region 11158 in 2011 February. Title: The PDFI_SS Electric Field Inversion Software Authors: Fisher, George H.; Kazachenko, Maria D.; Welsch, Brian T.; Sun, Xudong; Lumme, Erkka; Bercik, David J.; DeRosa, Marc L.; Cheung, Mark C. M. Bibcode: 2020ApJS..248....2F Altcode: 2019arXiv191208301F We describe the PDFI_SS software library, which is designed to find the electric field at the Sun's photosphere from a sequence of vector magnetogram and Doppler velocity measurements and estimates of horizontal velocities obtained from local correlation tracking using the recently upgraded Fourier Local Correlation Tracking code. The library, a collection of FORTRAN subroutines, uses the "PDFI" technique described by Kazachenko et al., but modified for use in spherical, Plate Carrée geometry on a staggered grid. The domain over which solutions are found is a subset of the global spherical surface, defined by user-specified limits of colatitude and longitude. Our staggered grid approach, based on that of Yee, is more conservative and self-consistent compared to the centered, Cartesian grid used by Kazachenko et al. The library can be used to compute an end-to-end solution for electric fields from data taken by the HMI instrument aboard NASA's SDO mission. This capability has been incorporated into the HMI pipeline processing system operating at SDO's Joint Science Operations Center. The library is written in a general and modular way so that the calculations can be customized to modify or delete electric field contributions, or used with other data sets. Other applications include "nudging" numerical models of the solar atmosphere to facilitate assimilative simulations. The library includes an ability to compute "global" (whole-Sun) electric field solutions. The library also includes an ability to compute potential magnetic field solutions in spherical coordinates. This distribution includes a number of test programs that allow the user to test the software. Title: The PDFI_SS Electric Field Inversion Software Authors: Fisher, George H.; Kazachenko, Maria D.; Welsch, Brian T.; Lumme, Erkka Bibcode: 2020zndo...3711571F Altcode: This is a copy of the PDFI_SS electric field inversion software, as described in arXiv 1912.08301. Title: The FLCT local correlation tracking software Authors: Fisher, George H.; Welsch, Brian T. Bibcode: 2020zndo...3711569F Altcode: FLCT consists of a library of functions, written in C, for performing tasks associated with local correlation tracking, and the approximate inverse operation, the warping of an image by a two-dimensional displacement function. The library is written in such a way that it can be called easily from either C or Fortran. The software also includes source code for two standalone executables, flct and warp, which will perform the correlation tracking or warping by reading input files and then creating output files that can be read from other applications, such as IDL. Title: The Simple Data Format (SDF) library Authors: Fisher, George; Bercik, David; Vernetti, Jack Bibcode: 2020zndo...3711188F Altcode: The SDF library contains the ability to read and write binary output files in Fortran, C, and IDL. Title: Contribution of Doppler Velocity to Active Region Energy and Helicity Flux Estimate Authors: Sun, Xudong; Schuck, Peter W.; Fisher, George H. Bibcode: 2019AAS...23440204S Altcode: The advent of routine photospheric vector magnetograms now allows for realistic estimate of active region (AR) energy and helicity flux. Such estimate requires information of the surface velocity field. Here, we calculate the energy and helicity flux for AR 12673 where significant Doppler flows (Vl) were observed along the magnetic polarity inversion line. Results based on the DAVE4VM velocity estimate (without Vl information) and the CGEM electric field inversion (with Vl) algorithms differ significantly, mainly due to the additional constraint from Vl. We argue that Dopper velocity needs to be included for realistic flux estimate. We describe an updated DAVE4VMWDV velocity estimate algorithm that incorporates such contribution. Title: Probing the Effect of Cadence on the Estimates of Photospheric Energy and Helicity Injections in Eruptive Active Region NOAA AR 11158 Authors: Lumme, E.; Kazachenko, M. D.; Fisher, G. H.; Welsch, B. T.; Pomoell, J.; Kilpua, E. K. J. Bibcode: 2019SoPh..294...84L Altcode: 2019arXiv190700367L We study how the input-data cadence affects the photospheric energy and helicity injection estimates in eruptive NOAA Active Region 11158. We sample the novel 2.25-minute vector magnetogram and Dopplergram data from the Helioseismic and Magnetic Imager (HMI) instrument onboard the Solar Dynamics Observatory (SDO) spacecraft to create input datasets of variable cadences ranging from 2.25 minutes to 24 hours. We employ state-of-the-art data processing, velocity, and electric-field inversion methods for deriving estimates of the energy and helicity injections from these datasets. We find that the electric-field inversion methods that reproduce the observed magnetic-field evolution through the use of Faraday's law are more stable against variable cadence: the PDFI (PTD-Doppler-FLCT-Ideal, where PTD refers to Poloidal-Toroidal Decomposition, and FLCT to Fourier Local Correlation Tracking) electric-field inversion method produces consistent injection estimates for cadences from 2.25 minutes up to two hours, implying that the photospheric processes acting on time scales below two hours contribute little to the injections, or that they are below the sensitivity of the input data and the PDFI method. On other hand, the electric-field estimate derived from the output of DAVE4VM (Differential Affine Velocity Estimator for Vector Magnetograms), which does not fulfill Faraday's law exactly, produces significant variations in the energy and helicity injection estimates in the 2.25 minutes - two hours cadence range. We also present a third, novel DAVE4VM-based electric-field estimate, which corrects the poor inductivity of the raw DAVE4VM estimate. This method is less sensitive to the changes of cadence, but it still faces significant issues for the lowest of considered cadences (≥ two hours). We find several potential problems in both PDFI- and DAVE4VM-based injection estimates and conclude that the quality of both should be surveyed further in controlled environments. Title: Erratum: “Why Is the Great Solar Active Region 12192 Flare-rich but CME-poor?” (2015, ApJL, 804, L28) Authors: Sun, Xudong; Bobra, Monica G.; Hoeksema, J. Todd; Liu, Yang; Li, Yan; Shen, Chenglong; Couvidat, Sebastien; Norton, Aimee A.; Fisher, George H. Bibcode: 2017ApJ...850L..43S Altcode: No abstract at ADS Title: Global Evolving Models of Photospheric Flux as Driven by Electric Fields Authors: DeRosa, Marc L.; Cheung, Mark; Kazachenko, Maria D.; Fisher, George H. Bibcode: 2017SPD....4811105D Altcode: We present a novel method for modeling the global radial magnetic field that is based on the incorporation of time series of photospheric electric fields. The determination of the electric fields is the result of a recently developed method that uses as input various data products from SDO/HMI, namely vector magnetic fields and line-of-sight Doppler images. For locations on the sphere where electric field data are unavailable, we instead use electric fields that are consistent with measurements of the mean differential rotation, meridional flow, and flux dispersal profiles. By combining these electric fields, a full-Sun model of the photospheric radial magnetic field can be advanced forward in time via Faraday's Law. Title: The Circulation and Closure of Electric Currents in the Solar Atmosphere Authors: Kazachenko, M.; Fisher, G. H.; Bercik, D. J.; Welsch, B. T.; Lynch, B. J. Bibcode: 2016AGUFMSH31B2579K Altcode: How much information about vertical and horizontal currents flowing inthe solar atmosphere can we learn from a single vector magnetogramtaken at the photosphere? It is well-known that one can determine theradial current density by taking the curl of the magnetic fieldcomponents parallel to an idealised photospheric surface. Here, weinvestigate the additional information that can be learned abouthorizontal currents flowing in the atmosphere above the photosphere.In particular, we study the radially integrated horizontal currentdistribution, expressed as a surface current density. In ourformalism, this surface-current density is projected onto thephotospheric surface, even though it represents currents flowing atall heights in the atmosphere. Horizontal currents reflect twosources: (1) currents flowing around radial magnetic distributions;and (2) horizontal currents that originate as radial currents at thephotosphere, become horizontal above it, and return to the photosphereagain as radial currents. Our aim is to derive two-dimensional``maps'' of how currents flow through the solar atmosphere that can bederived from vector magnetic field measurements at a single height. Title: A model for stealth coronal mass ejections Authors: Lynch, B. J.; Masson, S.; Li, Y.; DeVore, C. R.; Luhmann, J. G.; Antiochos, S. K.; Fisher, G. H. Bibcode: 2016JGRA..12110677L Altcode: 2016arXiv161208323L Stealth coronal mass ejections (CMEs) are events in which there are almost no observable signatures of the CME eruption in the low corona but often a well-resolved slow flux rope CME observed in the coronagraph data. We present results from a three-dimensional numerical magnetohydrodynamics (MHD) simulation of the 1-2 June 2008 slow streamer blowout CME that Robbrecht et al. (2009) called "the CME from nowhere." We model the global coronal structure using a 1.4 MK isothermal solar wind and a low-order potential field source surface representation of the Carrington Rotation 2070 magnetogram synoptic map. The bipolar streamer belt arcade is energized by simple shearing flows applied in the vicinity of the helmet streamer's polarity inversion line. The flows are large scale and impart a shear typical of that expected from the differential rotation. The slow expansion of the energized helmet streamer arcade results in the formation of a radial current sheet. The subsequent onset of expansion-induced flare reconnection initiates the stealth CME while gradually releasing the stored magnetic energy. We present favorable comparisons between our simulation results and the multiviewpoint SOHO-LASCO (Large Angle and Spectrometric Coronagraph) and STEREO-SECCHI (Sun Earth Connection Coronal and Heliospheric Investigation) coronagraph observations of the preeruption streamer structure and the initiation and evolution of the stealth streamer blowout CME. Title: Unexpectedly Strong Lorentz-Force Impulse Observed During a Solar Eruption Authors: Sun, X.; Fisher, G.; Torok, T.; Hoeksema, J. T.; Li, Y.; CGEM Team Bibcode: 2016usc..confE..12S Altcode: For fast coronal mass ejections (CMEs), the acceleration phase takes place in the low corona; the momentum process is presumably dominated by the Lorentz force. Using ultra-high-cadence vector magnetic data from the Helioseismic and Magnetic Imager (HMI) and numerical simulations, we show that the observed fast-evolving photospheric field can be used to characterize the impulse of the Lorentz force during a CME. While the peak Lorentz force concurs with the maximum ejecta acceleration, the observed total force impulse surprisingly exceeds the CME momentum by over an order of magnitude. We conjecture that most of the Lorentz force impulse is "trapped" in the thin layer of the photosphere above the HMI line-formation height and is counter-balanced by gravity. This implies a consequent upward plasma motion which we coin "gentle photospheric upwelling". The unexpected effect dominates the momentum processes, but is negligible for the energy budget, suggesting a complex coupling between different layers of the solar atmosphere during CMEs. Title: Deriving Potential Coronal Magnetic Fields from Vector Magnetograms Authors: Welsch, Brian T.; Fisher, George H. Bibcode: 2016SoPh..291.1681W Altcode: 2016SoPh..tmp..120W; 2015arXiv150308754W The minimum-energy configuration for the magnetic field above the solar photosphere is curl-free (hence, by Ampère's law, also current-free), so can be represented as the gradient of a scalar potential. Since magnetic fields are divergence free, this scalar potential obeys Laplace's equation, given an appropriate boundary condition (BC). With measurements of the full magnetic vector at the photosphere, it is possible to employ either Neumann or Dirichlet BCs there. Historically, the Neumann BC was used with available line-of-sight magnetic field measurements, which approximate the radial field needed for the Neumann BC. Since each BC fully determines the 3D vector magnetic field, either choice will, in general, be inconsistent with some aspect of the observed field on the boundary, due to the presence of both currents and noise in the observed field. We present a method to combine solutions from both Dirichlet and Neumann BCs to determine a hybrid, "least-squares" potential field, which minimizes the integrated square of the residual between the potential and actual fields. We also explore weighting the residuals in the fit by spatially uniform measurement uncertainties. This has advantages both in not overfitting the radial field used for the Neumann BC, and in maximizing consistency with the observations. We demonstrate our methods with SDO/HMI vector magnetic field observations of active region 11158, and find that residual discrepancies between the observed and potential fields are significant, and they are consistent with nonzero horizontal photospheric currents. We also analyze potential fields for two other active regions observed with two different vector magnetographs, and find that hybrid-potential fields have significantly less energy than the Neumann fields in every case - by more than 1032erg in some cases. This has major implications for estimates of free magnetic energy in coronal field models, e.g., non-linear force-free field extrapolations. Title: Unexpectedly Large Lorentz-Force Impulse Observed During a Solar Eruption Authors: Sun, Xudong; Fisher, George; Torok, Tibor; Hoeksema, Todd; Li, Yan; CGEM Team Bibcode: 2016shin.confE.158S Altcode: For fast coronal mass ejections (CMEs), the acceleration phase takes place in the low corona; the momentum process is presumably dominated by the Lorentz force. Using ultra-high-cadence vector magnetic data from the Helioseismic and Magnetic Imager (HMI) and numerical simulations, we show that the observed fast-evolving photospheric field can be used to characterize the impulse of the Lorentz force during a CME. While the peak Lorentz force concurs with the maximum ejecta acceleration, the observed total force impulse surprisingly exceeds the CME momentum by over an order of magnitude. We conjecture that most of the Lorentz force impulse is "trapped" in the thin layer of the photosphere above the HMI line-formation height and is counter-balanced by gravity. This implies a consequent upward plasma motion which we coin "gentle photospheric upwelling". The unexpected effect dominates the momentum processes, but is negligible for the energy budget, suggesting a complex coupling between different layers of the solar atmosphere during CMEs. Title: Streamer Blowout CME Initiation: Not Loss-of-Equilibrium, Not Flux-Cancellation, Not the Kink Instability, and Not the Torus Instability Authors: Lynch, Benjamin J.; Masson, S.; Li, Y.; DeVore, C. R.; Luhmann, J. G.; Antiochos, S. K.; Fisher, G. H. Bibcode: 2016shin.confE..49L Altcode: We present results from a three-dimensional numerical magnetohydrodynamics (MHD) simulation of the 2008 June 1-2 slow streamer blowout CME that Robbrecht et al. [2009] called 'the CME from nowhere.'

We investigate the CME initiation mechanism in detail, showing definitely the eruption is *not* caused by loss-of-equilibrium, flux-cancellation, the kink instability or the torus instability, rather, the rising sheared arcade becomes a CME in the traditional sense only when the eruptive flare reconnection occurs at the radial current sheet, forming a flux rope structure *during* the eruption.

We present favorable comparisons between our simulation results and the multi-viewpoint SOHO-LASCO and STEREO-SECCHI coronagraph observations of the pre-eruption streamer structure and the initiation and evolution of the stealth streamer blowout CME. We also present synthetic in-situ time series at r=15Rs of the plasma and field signatures of the flux rope CME and show qualitative agreement to the ICME observed by STB on 2008 June 6-7. Title: A Potential Field Model for Spherical Sub-domains Authors: Fisher, George H.; Bercik, David; Welsch, Brian; Kazachenko, Maria D.; CGEM Team Bibcode: 2016SPD....47.0308F Altcode: Potential field models are used widely in Solar Physics to estimate coronal magnetic field geometry and connectivity, to provide lower limits on magnetic energies, and to provide initial configurations for time-dependent models of magnetic fields in the solar atmosphere. Potential field models in a spherical geometry can be global, covering the entire Sun, or confined to localized sub-volumes of the sphere. Here, we focus on the latter case.We describe an efficient potential field model for localized spherical sub-volumes (wedges consisting of upper and lower limits of radius, co-latitude, and longitude), employing a finite-difference approach for the solution. The solution is derived in terms of a "poloidal" potential, which can then be used to find either the scalar potential or the vector potential for the magnetic field (if desired), as well as all three magnetic field components. The magnetic field components are computed on the faces of spherical voxels, and the finite difference grid is consistent with the well-known "Yee" grid. The inner spherical boundary is defined by radial magnetic field measurements, and at the outer radius a source-surface boundary condition is imposed.Potential field solutions on active region scales, at full HMI resolution, and with the source surface located a solar radius above the photosphere, can be obtained on a laptop computer in just a few minutes. The three-dimensional finite difference equations are solved using NCAR's FISHPACK elliptic equation solver.The potential field model was developed by the Coronal Global Evolutionary Model (CGEM) project, funded by the NASA and NSF Strategic Capabilities program. The potential field model described here was motivated by CGEM's need for such a model. The model will be released as open-source code when the model details are published. Title: Unexpectedly Strong Lorentz-Force Impulse Observed During a Solar Eruption Authors: Sun, Xudong; Fisher, George H.; Torok, Tibor; Hoeksema, Jon Todd; Li, Yan; CGEM Team Bibcode: 2016SPD....47.0628S Altcode: For fast coronal mass ejections (CMEs), the acceleration phase takes place in the low corona; the momentum process is presumably dominated by the Lorentz force. Using ultra-high-cadence vector magnetic data from the Helioseismic and Magnetic Imager (HMI) and numerical simulations, we show that the observed fast-evolving photospheric field can be used to characterize the impulse of the Lorentz force during a CME. While the peak Lorentz force concurs with the maximum ejecta acceleration, the observed total force impulse surprisingly exceeds the CME momentum by over an order of magnitude. We conjecture that most of the Lorentz force impulse is "trapped" in the thin layer of the photosphere above the HMI line-formation height and is counter-balanced by gravity. This implies a consequent upward plasma motion which we coin "gentle photospheric upwelling". The unexpected effect dominates the momentum processes, but is negligible for the energy budget, suggesting a complex coupling between different layers of the solar atmosphere during CMEs. Title: A Model for Stealth Coronal Mass Ejections Authors: Lynch, Benjamin J.; Masson, Sophie; Li, Yan; DeVore, C. Richard; Luhmann, Janet; Antiochos, Spiro K.; Fisher, George H. Bibcode: 2016SPD....47.0616L Altcode: Stealth coronal mass ejections (CMEs) are events in which there are almost no observable signatures of the CME eruption in the low corona but often a well-resolved slow flux rope CME observed in the coronagraph data. We present results from a three-dimensional numerical magnetohydrodynamics (MHD) simulation of the 2008 June 1-2 slow streamer blowout CME that Robbrecht et al. [2009] called “the CME from nowhere.” We model the global coronal structure using a 1.4 MK isothermal solar wind and a low-order potential field source surface representation of the Carrington Rotation 2070 magnetogram synoptic map. The bipolar streamer belt arcade is energized by simple shearing flows applied in the vicinity of the helmet streamer’s polarity inversion line. The slow expansion of the energized helmet-streamer arcade results in the formation of a radial current sheet. The subsequent onset of expansion-driven flare reconnection initiates the stealth CME while gradually releasing ~1.5E+30 erg of stored magnetic energy over the 20+ hour eruption duration. We show the energy flux available for flare heating and flare emission during the eruption is approximately two orders of magnitude below the energy flux required to heat the ambient background corona, thus confirming the “stealth” character of the 2008 June 1-2 CME’s lack of observable on disk signatures. We also present favorable comparisons between our simulation results and the multi-viewpoint SOHO-LASCO and STEREO-SECCHI coronagraph observations of the pre-eruption streamer structure and the initiation and evolution of the stealth streamer blowout CME. Title: Photospheric Electric Fields and Energy Fluxes in the Eruptive Active Region NOAA 11158 Authors: Kazachenko, Maria D.; Fisher, George H.; Welsch, Brian T.; Liu, Yang; Sun, Xudong Bibcode: 2015ApJ...811...16K Altcode: 2015arXiv150505974K How much electromagnetic energy crosses the photosphere in evolving solar active regions (ARs)? With the advent of high-cadence vector magnetic field observations, addressing this fundamental question has become tractable. In this paper, we apply the “PTD-Doppler-FLCT-Ideal” (PDFI) electric field inversion technique of Kazachenko et al. to a 6-day vector magnetogram and Doppler velocity sequence from the Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory to find the electric field and Poynting flux evolution in NOAA 11158, which produced an X2.2 flare early on 2011 February 15. We find photospheric electric fields ranging up to 2 V cm-1. The Poynting fluxes range from [-0.6 to 2.3] × {10}10 {erg} cm-2 s-1, mostly positive, with the largest contribution to the energy budget in the range of [{10}9-{10}10] erg cm-2 s-1. Integrating the instantaneous energy flux over space and time, we find that the total magnetic energy accumulated above the photosphere from the initial emergence to the moment before the X2.2 flare to be E=10.6× {10}32 {erg}, which is partitioned as 2.0×1032erg and 8.6× {10}32 {erg}, respectively, between free and potential energies. Those estimates are consistent with estimates from preflare nonlinear force-free field extrapolations and the Minimum Current Corona estimates, in spite of our very different approach. This study of photospheric electric fields demonstrates the potential of the PDFI approach for estimating Poynting fluxes and opens the door to more quantitative studies of the solar photosphere and more realistic data-driven simulations of coronal magnetic field evolution. Title: The Coronal Global Evolutionary Model: Using HMI Vector Magnetogram and Doppler Data to Model the Buildup of Free Magnetic Energy in the Solar Corona Authors: Fisher, G. H.; Abbett, W. P.; Bercik, D. J.; Kazachenko, M. D.; Lynch, B. J.; Welsch, B. T.; Hoeksema, J. T.; Hayashi, K.; Liu, Y.; Norton, A. A.; Dalda, A. Sainz; Sun, X.; DeRosa, M. L.; Cheung, M. C. M. Bibcode: 2015SpWea..13..369F Altcode: 2015arXiv150506018F The most violent space weather events (eruptive solar flares and coronal mass ejections) are driven by the release of free magnetic energy stored in the solar corona. Energy can build up on timescales of hours to days, and then may be suddenly released in the form of a magnetic eruption, which then propagates through interplanetary space, possibly impacting the Earth's space environment. Can we use the observed evolution of the magnetic and velocity fields in the solar photosphere to model the evolution of the overlying solar coronal field, including the storage and release of magnetic energy in such eruptions? The objective of CGEM, the Coronal Global Evolutionary Model, funded by the NASA/NSF Space Weather Modeling program, is to develop and evaluate such a model for the evolution of the coronal magnetic field. The evolving coronal magnetic field can then be used as a starting point for magnetohydrodynamic (MHD) models of the corona, which can then be used to drive models of heliospheric evolution and predictions of magnetic field and plasma density conditions at 1AU. Title: Why Is the Great Solar Active Region 12192 Flare-rich but CME-poor? Authors: Sun, Xudong; Bobra, Monica G.; Hoeksema, J. Todd; Liu, Yang; Li, Yan; Shen, Chenglong; Couvidat, Sebastien; Norton, Aimee A.; Fisher, George H. Bibcode: 2015ApJ...804L..28S Altcode: 2015arXiv150206950S; 2015ApJ...804L..28. Solar active region (AR) 12192 of 2014 October hosts the largest sunspot group in 24 years. It is the most prolific flaring site of Cycle 24 so far, but surprisingly produced no coronal mass ejection (CME) from the core region during its disk passage. Here, we study the magnetic conditions that prevented eruption and the consequences that ensued. We find AR 12192 to be “big but mild” its core region exhibits weaker non-potentiality, stronger overlying field, and smaller flare-related field changes compared to two other major flare-CME-productive ARs (11429 and 11158). These differences are present in the intensive-type indices (e.g., means) but generally not the extensive ones (e.g., totals). AR 12192's large amount of magnetic free energy does not translate into CME productivity. The unexpected behavior suggests that AR eruptiveness is limited by some relative measure of magnetic non-potentiality over the restriction of background field, and that confined flares may leave weaker photospheric and coronal imprints compared to their eruptive counterparts. Title: The Coronal Global Evolutionary Model (CGEM): Toward Routine, Time-Dependent, Data-Driven Modeling of the Active Corona Authors: Welsch, Brian T.; Cheung, Mark CM; Fisher, George H.; Kazachenko, Maria D.; Sun, Xudong Bibcode: 2015TESS....131106W Altcode: The Coronal Global Evolutionary Model (CGEM) is a model for the evolution of the magnetic field in the solar corona, driven using photospheric vector magnetic field and Doppler measurements by the HMI instrument on NASA's Solar Dynamics Observatory. Over days-long time scales, the coronal magnetic field configuration is determined quasi-statically using magnetofrictional relaxation. For a configuration that becomes unstable and erupts or undergoes rapid evolution, we can use the magnetofrictional configuration as the initial state for MHD simulations. The model will be run in both global configurations, covering the entire Sun, and local configurations, designed to model the evolution of the corona above active regions. The model uses spherical coordinates to realistically treat the large-scale coronal geometry. The CGEM project also includes the dissemination of other information derivable from HMI magnetogram data, such as (i) vertical and horizontal Lorentz forces computed over active region domains, to facilitate easier comparisons of flare/CME behavior and observed changes of the photospheric magnetic field, and (ii) estimates of the photospheric electric field and Poynting flux. We describe progress that we have made in development of both the coronal model and its input data, and discuss magnetic evolution in (i) the well-studied NOAA AR 11158 around the time of the 2011 February 15 X2.2 flare, and (ii) AR 11944 around the time of the 2014 January 7 X1.2 flare. Title: On the Relationship between Solar Magnetic Forces and CME Momenta Authors: Li, Yan; Lynch, Ben; Sun, Xudong; Welsch, Brian T.; Bercik, David J.; Fisher, George H. Bibcode: 2015TESS....130219L Altcode: Free magnetic energy is the energy source of solar flares and CMEs. At the initiation of a CME, the free magnetic energy converts to kinetic energy and few other types of energy. Observable magnetic field sudden changes have been found at the onset of flares. The Lorentz force around the onset of a flare have been formulated in recent studies and can be estimated using photospheric vector magnetic field data. It is proposed that outward Lorentz force impulses could be related to CME momenta. We analyze about 30 CMEs and their source region magnetic fields. The best vector magnetic field data are observed for active regions near the center of the solar disk. We first select CMEs that appear to be halo or partial halo CMEs in the LASCO images, and then we use STEREO SECCHI COR2 white light images to estimate CME mass and speed. We then estimate the Lorentz forces in the source active regions at the flare onset using SDO HMI photosheric vector magnetic field data. We report our studies and describe our analyses.This study is under the support of NSF grants. Title: Why Is the Great Solar Active Region 12192 CME-Poor? Authors: Sun, Xudong; Bobra, Monica G.; Hoeksema, Todd; Liu, Yang; Li, Yan; Shen, Chenglong; Couvidat, Sebastien; Norton, Aimee A.; Fisher, George H. Bibcode: 2015TESS....140802S Altcode: Solar active region (AR) 12192 of October 2014 hosts the largest sunspot group in 24 years. It is the most prolific flaring site of Cycle 24, but surprisingly produced no coronal mass ejection (CME) from the core region during its disk passage. Here, we study the magnetic conditions that prevented eruption and the consequences that ensued. We find AR 12192 to be "big but mild"; its core region exhibits weaker non-potentiality, stronger overlying field, and smaller flare-related field changes compared to two other major flare-CME-productive ARs (11429 and 11158). These differences are present in the intensive-type indices (e.g., means) but generally not the extensive ones (e.g., totals). AR 12192's large amount of magnetic free energy does not translate into CME productivity. The unexpected behavior suggests that AR eruptiveness is limited by some relative measure of magnetic non-potentiality over the restriction of background field, and that confined flares may leave weaker photospheric and coronal imprints compared to their eruptive counterparts. Title: Sign Singularity and Flares in Solar Active Region NOAA 11158 Authors: Sorriso-Valvo, L.; De Vita, G.; Kazachenko, M. D.; Krucker, S.; Primavera, L.; Servidio, S.; Vecchio, A.; Welsch, B. T.; Fisher, G. H.; Lepreti, F.; Carbone, V. Bibcode: 2015ApJ...801...36S Altcode: 2015arXiv150104279S Solar Active Region NOAA 11158 has hosted a number of strong flares, including one X2.2 event. The complexity of current density and current helicity are studied through cancellation analysis of their sign-singular measure, which features power-law scaling. Spectral analysis is also performed, revealing the presence of two separate scaling ranges with different spectral index. The time evolution of parameters is discussed. Sudden changes of the cancellation exponents at the time of large flares and the presence of correlation with Extreme-Ultra-Violet and X-ray flux suggest that eruption of large flares can be linked to the small-scale properties of the current structures. Title: Modeling the Convection Zone-to-Corona System over Global Spatial Scales Authors: Abbett, W. P.; Bercik, D. J.; Fisher, G. H. Bibcode: 2014AGUFMSH44A..01A Altcode: How magnetic energy and flux emerges from the turbulent convective interior of the Sun into the solar atmosphere is of great importance to a number of challenging problems in solar physics. With the wealth of data from missions such as SDO, Hinode, and IRIS, it is evident that the dynamic interaction of magnetic structures at the photosphere and in the solar atmosphere occurs over a vast range of spatial and temporal scales. Emerging active regions often develop magnetic connections to other regions of activity some distance away on the solar disk, and always emerge into a global coronal field whose structural complexity is a function of the solar cycle. Yet even small-scale dynamic interactions (e.g., processes at granular or supergranular scales in the photosphere) can trigger rapid changes in the large-scale coronal field sufficient to power eruptive events such as coronal mass ejections, or solar flares. The challenge of modeling this system in its entirety is that the magnetic field not only spans multiple scales, but also regions whose physical conditions vary dramatically. We will summarize recent progress in the effort to dynamically model the upper convection zone-to-corona system over large spatial scales, and will present the latest results from a new, global radiative-MHD model of the upper convection zone-to-corona system, RADMHD2S. We will characterize the flux of electromagnetic energy into the solar atmosphere as flux systems of different scales dynamically interact, and discuss how physics-based models of the convection zone-to-corona system can be used to guide the development and testing of data-driven models. Title: A Comprehensive Method of Estimating Electric Fields from Vector Magnetic Field and Doppler Measurements Authors: Kazachenko, Maria D.; Fisher, George H.; Welsch, Brian T. Bibcode: 2014ApJ...795...17K Altcode: 2014arXiv1404.4027K Photospheric electric fields, estimated from sequences of vector magnetic field and Doppler measurements, can be used to estimate the flux of magnetic energy (the Poynting flux) into the corona and as time-dependent boundary conditions for dynamic models of the coronal magnetic field. We have modified and extended an existing method to estimate photospheric electric fields that combines a poloidal-toroidal decomposition (PTD) of the evolving magnetic field vector with Doppler and horizontal plasma velocities. Our current, more comprehensive method, which we dub the "PTD-Doppler-FLCT Ideal" (PDFI) technique, can now incorporate Doppler velocities from non-normal viewing angles. It uses the FISHPACK software package to solve several two-dimensional Poisson equations, a faster and more robust approach than our previous implementations. Here, we describe systematic, quantitative tests of the accuracy and robustness of the PDFI technique using synthetic data from anelastic MHD (ANMHD) simulations, which have been used in similar tests in the past. We find that the PDFI method has less than 1% error in the total Poynting flux and a 10% error in the helicity flux rate at a normal viewing angle (θ = 0) and less than 25% and 10% errors, respectively, at large viewing angles (θ < 60°). We compare our results with other inversion methods at zero viewing angle and find that our method's estimates of the fluxes of magnetic energy and helicity are comparable to or more accurate than other methods. We also discuss the limitations of the PDFI method and its uncertainties. Title: Relationship between the photospheric Poynting flux and the active region luminosity Authors: Kazachenko, Maria D.; Canfield, Richard C.; Fisher, George H.; Hudson, Hugh S.; Welsch, Brian Bibcode: 2014AAS...22412349K Altcode: How does energy radiated by active regions compare with magnetic energy that propagates lower across the photosphere? This is a fundamental question for energy storage and release in active regions, yet it is presently poorly understood. In this work we quantify and compare both energy terms using SDO observations of the active region (AR) 11520. To quantify the magnetic energy crossing the photosphere, or the Poynting flux, we need to know both the magnetic field vector B and electric field vector E as well. Our current electric field inversion technique, PDFI, combines the Poloidal-Toroidal-Decomposition method with information from Doppler measurements, Fourier local correlation tracking (FLCT) results, and the ideal MHD constraint, to determine the electric field from vector magnetic field and Doppler data. We apply the PDFI method to a sequence of Helioseismic and Magnetic Imager (HMI/SDO) vector magnetogram data, to find the electric-field and hence the Poynting-flux evolution in AR 11520. We find that most of the magnetic energy in this AR is injected in the range of $10^7$ to $10^8$ $ergs/{cm^2 s}$, with the largest fluxes reaching $10^{10}$ $ergs/{cm^2 s}$. Integrating over the active region this yields a total energy of order $10^{28}$ ergs/s. To quantify the active region luminosity, we use EUV Variability Experiment (EVE) and Atmospheric Imaging Assembly (AIA) spectrally resolved observations. We find the active region luminosity of order $10^{28}$ ergs/s. We compare derived magnetic and radiated energy fluxes on different temporal and spatial scales and estimate their uncertainties. We also discuss the roles that potential/non-potential and emerging/shearing terms play in the total magnetic energy budget. Title: The Coronal Global Evolutionary Model (CGEM): Highlights of the First Year Authors: Fisher, George H. Bibcode: 2014AAS...22432318F Altcode: The Coronal Global Evolutionary Model (CGEM) is a model for the evolution of the magnetic field in the solar corona, driven by vector and line-of-sight magnetogram data, along with Doppler data, taken from HMI instrument on NASA's SDO Mission. On long time scales, the magnetic field evolution is computed quasi-statically using the magnetofrictional method. For a configuration which becomes unstable and erupts or undergoes rapid evolution, we will use the magnetofrictional configuration as the initial state for an MHD simulation. The model will be run in both global configurations, covering the entire Sun, and local configurations, designed to model the evolution of the corona above active regions. In both cases, the model will use spherical coordinates to enable a more realistic geometry in the outer corona. The CGEM project also includes the dissemination of other information derivable from HMI magnetogram data, such as the vertical and horizontal Lorentz-forces computed over active region domains, to facilitate easier comparisons of flare/CME behavior and observed changes of the photospheric magnetic field.We describe progress we have made both on the development of this new model, and our continued development of our prototype Cartesian model, which was the basis for the CGEM proposal. We will discuss updated simulations that use our prototype model to study the evolution of NOAA AR 11158 over the time period that includes the 2011 February 15 X-class flare. Title: Photospheric Flows, Lorentz Forces, and Solar-Eruption Initiation Authors: Fisher, George; Kazachenko, Maria Bibcode: 2014cosp...40E.874F Altcode: Eruptive Flares and coronal mass ejections (CMEs) are almost certainly magnetically driven. We discuss the role that the Lorentz force must play in driving an eruption, and how both the radial and horizontal components of this force can be related to changes that occur in observations of the vector magnetic field observed at the photosphere. We then review recent observational work on observed flows in the solar atmosphere, and how these flows might be related to changes in the Lorentz force observed during flares. Flows in magnetized regions of the photosphere also generate electric fields, which can affect the flux of magnetic energy transported across the photosphere and into the chromosphere and corona, and result in changes to the magnetic field there as well. We will discuss how such electric fields are incorporated into models of active-regions, to study the buildup of electric currents and the ejection of plasma in the context of our recently funded project, the ``Coronal Global Evolutionary Model (CGEM)'', a collaboration between UC Berkeley, Stanford University, and the Lockheed Martin Solar and Astrophysics Laboratory. Title: Obtaining Photospheric Electric Field Maps and Poynting Fluxes from vector magnetograms and Doppler data: Tests and Data Driving Applications Authors: Kazachenko, Maria; Fisher, George; Welsch, Brian Bibcode: 2014cosp...40E1439K Altcode: Quantitative studies of the flow of magnetic energy through the solar photosphere require a knowledge of the magnetic field vector B - and knowledge of the electric field E as well. We have modified and improved the technique Fisher et al. developed in 2012, which combines a poloidal-toroidal decomposition (PTD) to determine contributions to E from Faraday's law, with additional non-inductive contributions arising from flux emergence near polarity inversion lines, determined from Doppler measurements. The new technique, which we call the ``PTD Doppler FLCT Ideal'' (or PDFI) technique, incorporates Doppler information from non-normal viewing angles, and adopts the faster and more robust FISHPACK software for solutions of the two-dimensional Poisson equations. We demonstrate the performance using synthetic data from the anelastic pseudo-spectral ANMHD simulations that were used in the recent comparison of velocity inversion techniques (Welsch et al. 2007) and the PTD inversion (Fisher et al. 2012). We find that the PDFI method has roughly 10% reconstruction errors (it predicts roughly 100% of the photospheric Poynting flux and 110% of the helicity flux rate at normal viewing angles, consistent with Fisher et al. (2012) results, and 90% of Poynting flux and 110% helicity flux at theta=30 degrees). We conclude that the PDFI method can be routinely applied to observed magnetic field data and, as an example, apply it to the 6-day HMI/SDO vector magnetogram sequence centered at AR11158, where an X2.2 flare occurred. We discuss how our electric field maps are used to drive coronal magnetic field with a global evolutionary model, or CGEM, a collaborative effort from the UC Berkeley Space Sciences Laboratory (SSL), Stanford University, and Lockheed-Martin. Title: Estimating active region luminosity using EVE/SDO observations Authors: Kazachenko, Maria D.; Hudson, H. S.; Fisher, G. H.; Canfield, R. C. Bibcode: 2013SPD....44...44K Altcode: Do solar active regions typically radiate more coronal energy during flares than the quiescent periods between them? This is a fundamental question for storage and release models of flares and active regions, yet it is presently poorly answered by observations. The EUV Variability Experiment (EVE) on the Solar Dynamics Observatory (SDO) provides spectrally resolved observations of the Sun in the "Sun-as-a-point source" mode. It covers a wide range of temperatures and thus allows a detailed study of thermal emissions. Here we present two approaches for computing the active region luminosity, using EVE observations of fourteen Fe lines (FeIX-FeXXIV). In the first approach, we analyze EVE data in a time-series sense, when only one active region is present on the disk; this allows us to subtract the background due to the quiet sun and get the contribution from the active region alone. In the second approach, we analyze correlations of the radiative signatures with proxy indices (total solar magnetic and Poynting fluxes) during several months of data, when multiple active regions are present on the solar disk. We discuss capabilities of the two approaches, and what we can learn from them.Abstract (2,250 Maximum Characters): Do solar active regions typically radiate more coronal energy during flares than the quiescent periods between them? This is a fundamental question for storage and release models of flares and active regions, yet it is presently poorly answered by observations. The EUV Variability Experiment (EVE) on the Solar Dynamics Observatory (SDO) provides spectrally resolved observations of the Sun in the "Sun-as-a-point source" mode. It covers a wide range of temperatures and thus allows a detailed study of thermal emissions. Here we present two approaches for computing the active region luminosity, using EVE observations of fourteen Fe lines (FeIX-FeXXIV). In the first approach, we analyze EVE data in a time-series sense, when only one active region is present on the disk; this allows us to subtract the background due to the quiet sun and get the contribution from the active region alone. In the second approach, we analyze correlations of the radiative signatures with proxy indices (total solar magnetic and Poynting fluxes) during several months of data, when multiple active regions are present on the solar disk. We discuss capabilities of the two approaches, and what we can learn from them. Title: The Coronal Global Evolutionary Model (CGEM) Authors: Fisher, George H.; DeRosa, M. L.; Hoeksema, J. T. Bibcode: 2013SPD....4410102F Altcode: The Coronal Global Evolutionary Model, or CGEM, is a collaborative effort from the UC Berkeley Space Sciences Laboratory (SSL), Stanford University, and Lockheed-Martin. In work that led up to the selection of this project, the team demonstrated its capability to use sequences of vector magnetograms and Dopplergrams from the Helioseismic and Magnetic Imager (HMI) instrument aboard the SDO to drive a magnetofrictional (MF) model of the coronal magnetic field in AR 11158, which produced an X2.2 flare. We will implement this MF model in spherical coordinates to enable real-time, long-term modeling of the non-potential coronal magnetic field, both globally and for individual active region (ARs). The model's Earth-facing hemisphere will be driven using electric fields derived from the observed evolution of photospheric line-of-sight magnetic fields and electric currents. Far-side data inputs will be from an existing flux transport code, combined with HMI far-side observations of new active regions, with empirical parametrizations of orientation and flux. Because this model includes large-scale coronal electric currents, it is a substantial improvement over existing real-time global coronal models, which assume potential fields. Data products available from the model will include: 1) the evolving photospheric electric field, Poynting flux, and helicity flux; 2) estimates of coronal free energy and non-potential geometry and topology; 3) initial and time-dependent boundary conditions for MHD modeling of active regions; and 4) time-dependent boundary conditions and flux tube expansion factors for MHD and empirical solar wind models. Unstable configurations found from MF models will be dynamically evolved with local and global MHD codes. Modules used to derive surface electric fields from magnetic evolution will be incorporated into the SDO/HMI data pipeline, and data products will be distributed through the Joint Science Operations Center (JSOC) and directly to space weather forecasters and users. The electric field and MF codes will be delivered to the Community Coordinated Modeling Center (CCMC) for science analysis and use with other models. This project is being jointly funded by NASA and NSF. Title: A Magnetic Calibration of Photospheric Doppler Velocities Authors: Welsch, Brian T.; Fisher, George H.; Sun, Xudong Bibcode: 2013ApJ...765...98W Altcode: 2012arXiv1201.2451W The zero point of measured photospheric Doppler shifts is uncertain for at least two reasons: instrumental variations (from, e.g., thermal drifts); and the convective blueshift, a known correlation between intensity and upflows. Accurate knowledge of the zero point is, however, useful for (1) improving estimates of the Poynting flux of magnetic energy across the photosphere, and (2) constraining processes underlying flux cancellation, the mutual apparent loss of magnetic flux in closely spaced, opposite-polarity magnetogram features. We present a method to absolutely calibrate line-of-sight (LOS) velocities in solar active regions (ARs) near disk center using three successive vector magnetograms and one Dopplergram coincident with the central magnetogram. It exploits the fact that Doppler shifts measured along polarity inversion lines (PILs) of the LOS magnetic field determine one component of the velocity perpendicular to the magnetic field, and optimizes consistency between changes in LOS flux near PILs and the transport of transverse magnetic flux by LOS velocities, assuming that ideal electric fields govern the magnetic evolution. Previous calibrations fitted the center-to-limb variation of Doppler velocities, but this approach cannot, by itself, account for residual convective shifts at the limb. We apply our method to vector magnetograms of AR 11158, observed by the Helioseismic and Magnetic Imager aboard the Solar Dynamics Observatory, and find clear evidence of offsets in the Doppler zero point in the range of 50-550 m s-1. In addition, we note that a simpler calibration can be determined from an LOS magnetogram and Dopplergram pair from the median Doppler velocity among all near-disk-center PIL pixels. We briefly discuss shortcomings in our initial implementation, and suggest ways to address these. In addition, as a step in our data reduction, we discuss the use of temporal continuity in the transverse magnetic field direction to correct apparently spurious fluctuations in resolution of the 180° ambiguity. Title: Photospheric Drivers of Coronal Evolution Authors: Welsch, B. T.; Kazachenko, M.; Fisher, G. H.; Cheung, M. C. M.; DeRosa, M. L.; CGEM Team Bibcode: 2013enss.confE.108W Altcode: Flares and coronal mass ejections (CMEs) are driven by the release of free magnetic energy stored in the coronal magnetic field. While this energy is stored in the corona, photospheric driving must play a central role in its injection, storage, and release, since magnetic fields present in the corona originated within the solar interior, and are anchored at the photosphere. Also, the corona's low diffusivity and high Alfven speed (compared to that at the photosphere) imply that the large-scale coronal field essentially maintains equilibrium (outside of episodic flares and CMEs!), and therefore only evolves due to forcing from photospheric evolution. But fundamental questions about each stage of this "storage and release" paradigm remain open: How does free magnetic energy build up in the corona? How is this energy stored? And what triggers its release? The unprecedented combination of high cadence, resolution, and duty cycle of the HMI vector magnetograph enables modeling coronal magnetic evolution in response to photospheric driving, a powerful approach to addressing these questions. I will discuss our efforts to use HMI vector magneotgrams of AR 11158 to derive time-dependent boundary conditions for a data-driven coronal magnetic field model. These efforts will play a key role in the planned Coronal Global Evolutionary Model (CGEM), a data-driven, time-dependent model of the global coronal field. This work is supported by NASA's Living With a Star program and NSF's Division of Atmospheric and Geospace Sciences. Title: Evolution of the Photospheric Vector Magnetic Field in HMI Data Authors: Welsch, B. T.; Fisher, G. H. Bibcode: 2012AGUFMSH13A2243W Altcode: We discuss aspects of magnetic field structure and evolution in HMI data, including artifacts of the observation procedure and data reduction, and characterization of noise in the magnetic variables and their rates of change. Title: The evolution of the electric field and the Poynting and Helicity Fluxes in NOAA AR 11158 Authors: Kazachenko, Maria D.; Fisher, George H.; Welsch, Brian T. Bibcode: 2012shin.confE..44K Altcode: The existence of systematic measurements of vector magnetic fields and Doppler shifts allows us to estimate electric field in the photosphere, by solving Faraday's law, using a Poloidal-Toroidal Decomposition (PTD) of the magnetic field and its partial time derivative, as well as incorporating information from Doppler shifts (Fisher et al. 2012). The method is based on solving a set of two-dimensional Poisson equations. We have recently modified the method in the following two ways. First, we improvedthe speed and accuracy of the Poisson equation solver using the FISHPACK elliptic partial differential equation software developed at NCAR, employing Neumann boundary conditions appropriate for zero electric fields on the vector-magnetogram boundary. Second, we developed a more general procedure which allows us to calculate electric fields from magnetic fields observed at non-zero viewing angles. We apply the improved technique to ANMHD-simulation test case with a known electric field and find that it yields more accurate values of Electric field, Poynting and helicity fluxes than before. We then apply our method to three-days-long HMI data-set centered on AR 11158, which produced an X2.2 flare. We present our first results of electric field, helicity and Poynting flux evolutions in AR 11158. Title: Using Electric Fields to drive simulations of the solar coronal magnetic field Authors: Fisher, George H.; Cheung, Mark; DeRosa, Marc; Kazachenko, Maria; Welsch, Brian; Hoeksema, Todd; Sun, Xudong Bibcode: 2012shin.confE..47F Altcode: The availability of high-cadence vector magnetograms and Doppler flow information measured from the HMI instrument on SDO make it possible to determine the electric field at the solar photosphere. This electric field, in turn, can be used to drive time-dependent simulations of the magnetic field in the solar corona, employing the MHD equations, or simpler time-dependent models such as the magneto-frictional (MF) model. Here, we demonstrate these concepts by using electric fields determined from HMI data to drive a time-dependent MF model of the solar corona in the volume overlying the photosphere near NOAA AR 11158. Title: Global Forces in Eruptive Solar Flares: The Lorentz Force Acting on the Solar Atmosphere and the Solar Interior Authors: Fisher, George H.; Bercik, D. J.; Welsch, B. T.; Hudson, H. S. Bibcode: 2012AAS...22020440F Altcode: We compute the change in the Lorentz force integrated over the outer solar atmosphere implied by observed changes in vector magnetograms that occur during large, eruptive solar flares. This force perturbation should be balanced by an equal and opposite force perturbation acting on the solar photosphere and solar interior. The resulting expression for the estimated force change in the solar interior generalizes the earlier expression presented by Hudson, Fisher, and Welsch, providing horizontal as well as vertical force components, and provides a more accurate result for the vertical component of the perturbed force. We show that magnetic eruptions should result in the magnetic field at the photosphere becoming more horizontal, and hence should result in a downward (toward the solar interior) force change acting on the photosphere and solar interior, as recently argued from an analysis of magnetogram data by Wang and Liu. We suggest the existence of an observational relationship between the force change computed from changes in the vector magnetograms, the outward momentum carried by the ejecta from the flare, and the properties of the helioseismic disturbance driven by the downward force change. We use the impulse driven by the Lorentz-force change in the outer solar atmosphere to derive an upper limit to the mass of erupting plasma that can escape from the Sun. Finally, we compare the expected Lorentz-force change at the photosphere with simple estimates from flare-driven gasdynamic disturbances and from an estimate of the perturbed pressure from radiative backwarming of the photosphere in flaring conditions. Title: Finding Electric Fields, Poynting and Helicity Fluxes from Vector Magnetograms Authors: Kazachenko, Maria; Fisher, G. H.; Welsch, B. T. Bibcode: 2012AAS...22020210K Altcode: Existence of systematic measurements of vector magnetic fields allows us to estimate electric field in the photosphere, using Poloidal-Toroidal Decomposition of the magnetic field and its partial time derivative (Fisher et l. 2011). The PTD method is based on solving a set of Poisson equations which in the past has been done using Fast Fourier Transform techniques. We modify the existing PTD method by improving the poisson solver using a package of solvers for elliptic partial differential equations called Fishpack. We apply the PTD with a new Poisson equation solver to several test cases with a known electric field. We find that for the ANMHD simulation test case application of the new poisson solver yields a more accurate values of electric field, Poisson and helicity fluxes than before. We further investigate the applicability of our method to other test cases using simulations of M. Cheung and Y. Fan and also HMI vector magnetograms. Title: A First Look at Magnetic Field Data Products from SDO/HMI Authors: Liu, Y.; Scherrer, P. H.; Hoeksema, J. T.; Schou, J.; Bai, T.; Beck, J. G.; Bobra, M.; Bogart, R. S.; Bush, R. I.; Couvidat, S.; Hayashi, K.; Kosovichev, A. G.; Larson, T. P.; Rabello-Soares, C.; Sun, X.; Wachter, R.; Zhao, J.; Zhao, X. P.; Duvall, T. L., Jr.; DeRosa, M. L.; Schrijver, C. J.; Title, A. M.; Centeno, R.; Tomczyk, S.; Borrero, J. M.; Norton, A. A.; Barnes, G.; Crouch, A. D.; Leka, K. D.; Abbett, W. P.; Fisher, G. H.; Welsch, B. T.; Muglach, K.; Schuck, P. W.; Wiegelmann, T.; Turmon, M.; Linker, J. A.; Mikić, Z.; Riley, P.; Wu, S. T. Bibcode: 2012ASPC..455..337L Altcode: The Helioseismic and Magnetic Imager (HMI; Scherrer & Schou 2011) is one of the three instruments aboard the Solar Dynamics Observatory (SDO) that was launched on February 11, 2010 from Cape Canaveral, Florida. The instrument began to acquire science data on March 24. The regular operations started on May 1. HMI measures the Doppler velocity and line-of-sight magnetic field in the photosphere at a cadence of 45 seconds, and the vector magnetic field at a 135-second cadence, with a 4096× 4096 pixels full disk coverage. The vector magnetic field data is usually averaged over 720 seconds to suppress the p-modes and increase the signal-to-noise ratio. The spatial sampling is about 0".5 per pixel. HMI observes the Fe i 6173 Å absorption line, which has a Landé factor of 2.5. These data are further used to produce higher level data products through the pipeline at the HMI-AIA Joint Science Operations Center (JSOC) - Science Data Processing (Scherrer et al. 2011) at Stanford University. In this paper, we briefly describe the data products, and demonstrate the performance of the HMI instrument. We conclude that the HMI is working extremely well. Title: Search and study of lightnings on planets of the Solar System Authors: Zakharenko, V.; Konovalenko, A.; Kolyadin, V.; Zarka, P.; Grissmeier, J. -M.; Mylostna, K.; Litvinenko, G.; Sidorchuk, M.; Rucker, H.; Cecconi, B.; Coffre, A.; Denis, L.; Shevchenko, V.; Nikolaenko, V.; Fisher, G. Bibcode: 2012EGUGA..14.8341Z Altcode: Following the recent successful identification of lightning on Saturn recorded by ground-based radio telescope UTR-2 and spasecraft Cassini, we continued to study and search for electrostatic discharges on other planets of the Solar System. With the help of the receiving equipment with high frequency and time resolution the dispersion delay of short powerful discharges was fixed in the frequency band 16.5...33.0 MHz, that uniquely allows as to distinguish the lightnings and terrestrial broadband interference. We also defined other parameters of their radio emission. Uranus, Jupiter and Venus were selected as the following objects for searching. Observations were carried out and are currently under processing. Title: Global Forces in Eruptive Solar Flares: The Lorentz Force Acting on the Solar Atmosphere and the Solar Interior Authors: Fisher, G. H.; Bercik, D. J.; Welsch, B. T.; Hudson, H. S. Bibcode: 2012SoPh..277...59F Altcode: 2010arXiv1006.5247F; 2011SoPh..tmp..419F; 2011SoPh..tmp..415F We compute the change in the Lorentz force integrated over the outer solar atmosphere implied by observed changes in vector magnetograms that occur during large, eruptive solar flares. This force perturbation should be balanced by an equal and opposite force perturbation acting on the solar photosphere and solar interior. The resulting expression for the estimated force change in the solar interior generalizes the earlier expression presented by Hudson, Fisher, and Welsch (Astron. Soc. Pac. CS-383, 221, 2008), providing horizontal as well as vertical force components, and provides a more accurate result for the vertical component of the perturbed force. We show that magnetic eruptions should result in the magnetic field at the photosphere becoming more horizontal, and hence should result in a downward (toward the solar interior) force change acting on the photosphere and solar interior, as recently argued from an analysis of magnetogram data by Wang and Liu (Astrophys. J. Lett. 716, L195, 2010). We suggest the existence of an observational relationship between the force change computed from changes in the vector magnetograms, the outward momentum carried by the ejecta from the flare, and the properties of the helioseismic disturbance driven by the downward force change. We use the impulse driven by the Lorentz-force change in the outer solar atmosphere to derive an upper limit to the mass of erupting plasma that can escape from the Sun. Finally, we compare the expected Lorentz-force change at the photosphere with simple estimates from flare-driven gasdynamic disturbances and from an estimate of the perturbed pressure from radiative backwarming of the photosphere in flaring conditions. Title: Radiative Cooling in MHD Models of the Quiet Sun Convection Zone and Corona Authors: Abbett, W. P.; Fisher, G. H. Bibcode: 2012SoPh..277....3A Altcode: 2011arXiv1102.1035A We present a series of numerical simulations of the quiet-Sun plasma threaded by magnetic fields that extend from the upper convection zone into the low corona. We discuss an efficient, simplified approximation to the physics of optically thick radiative transport through the surface layers, and investigate the effects of convective turbulence on the magnetic structure of the Sun's atmosphere in an initially unipolar (open field) region. We find that the net Poynting flux below the surface is on average directed toward the interior, while in the photosphere and chromosphere the net flow of electromagnetic energy is outward into the solar corona. Overturning convective motions between these layers driven by rapid radiative cooling appears to be the source of energy for the oppositely directed fluxes of electromagnetic energy. Title: Can We Determine Electric Fields and Poynting Fluxes from Vector Magnetograms and Doppler Measurements? Authors: Fisher, G. H.; Welsch, B. T.; Abbett, W. P. Bibcode: 2012SoPh..277..153F Altcode: 2011arXiv1101.4086F The availability of vector-magnetogram sequences with sufficient accuracy and cadence to estimate the temporal derivative of the magnetic field allows us to use Faraday's law to find an approximate solution for the electric field in the photosphere, using a Poloidal-Toroidal Decomposition (PTD) of the magnetic field and its partial time derivative. Without additional information, however, the electric field found from this technique is under-determined - Faraday's law provides no information about the electric field that can be derived from the gradient of a scalar potential. Here, we show how additional information in the form of line-of-sight Doppler-flow measurements, and motions transverse to the line-of-sight determined with ad-hoc methods such as local correlation tracking, can be combined with the PTD solutions to provide much more accurate solutions for the solar electric field, and therefore the Poynting flux of electromagnetic energy in the solar photosphere. Reliable, accurate maps of the Poynting flux are essential for quantitative studies of the buildup of magnetic energy before flares and coronal mass ejections. Title: Momentum Distribution in Solar Flare Processes Authors: Hudson, H. S.; Fletcher, L.; Fisher, G. H.; Abbett, W. P.; Russell, A. Bibcode: 2012SoPh..277...77H Altcode: We discuss the consequences of momentum conservation in processes related to solar flares and coronal mass ejections (CMEs), in particular describing the relative importance of vertical impulses that could contribute to the excitation of seismic waves ("sunquakes"). The initial impulse associated with the primary flare energy transport in the impulsive phase contains sufficient momentum, as do the impulses associated with the acceleration of the evaporation flow (the chromospheric shock) or the CME itself. We note that the deceleration of the evaporative flow, as coronal closed fields arrest it, will tend to produce an opposite impulse, reducing the energy coupling into the interior. The actual mechanism of the coupling remains unclear at present. Title: Preface Authors: Fan, Yuhong; Fisher, George; Leibacher, John Bibcode: 2012SoPh..277....1F Altcode: 2011SoPh..tmp..423F No abstract at ADS Title: Electric Fields and Poynting Fluxes from Vector Magnetograms Authors: Fisher, G. H.; Welsch, B. T.; Abbett, W. P. Bibcode: 2012decs.confE..75F Altcode: The availability of vector-magnetogram sequences with sufficient accuracy and cadence to estimate the temporal derivative of the magnetic field allows us to use Faraday's law to find an approximate solution for the electric field in the photosphere, using a Poloidal-Toroidal Decomposition (PTD) of the magnetic field and its partial time derivative. Without additional information, however, the electric field found from this technique is under-determined - Faraday's law provides no information about the electric field that can be derived from the gradient of a scalar potential. Here, we show how additional information in the form of line-of-sight Doppler-flow measurements, and motions transverse to the line-of-sight determined with ad-hoc methods such as local correlation tracking, can be combined with the PTD solutions to provide much more accurate solutions for the solar electric field, and therefore the Poynting flux of electromagnetic energy in the solar photosphere. Reliable, accurate maps of the Poynting flux are essential for quantitative studies of the buildup of magnetic energy before flares and coronal mass ejections. Title: Determining electric fields from vector magnetograms. Authors: Kazachenko, M.; Fisher, G. H.; Welsch, B. T. Bibcode: 2012decs.confE..98K Altcode: Existence of systematic measurements of vector magnetic fields allows us to estimate electric field in the photosphere, using Poloidal-Toroidal Decomposition of the magnetic field and its partial time derivative (Fisher et l. 2011). The PTD method is based on solving a set of Poisson equations which in the past has been done using Fast Fourier Transform techniques. We modify the existing PTD method by improving the poisson solver using a package of solvers for elliptic partial differential equations called Fishpack. We apply the PTD with a new Poisson equation solver to several test cases with a known electric field. We find that for the ANMHD simulation test case application of the new poisson solver yields a more accurate values of electric field than before. We further investigate the applicability of our method to other test cases using simulations of M. Cheung and Y. Fan. Title: Roles for Data Assimilation in Studying Solar Flares & CMEs Authors: Welsch, B. T.; Abbett, W. P.; Fisher, G. H. Bibcode: 2011AGUFMSH54A..05W Altcode: Solar flares and coronal mass ejections (CMEs) are driven by the sudden release of free magnetic energy stored in electric currents the solar corona. While there is a consensus that free energy enters the corona from the solar interior, there is ongoing debate about the physical processes primarily responsible for transporting free energy into the corona and / or triggering its release once there. Since direct measurements of the coronal vector magnetic field, necessary to quantify coronal currents, are currently not feasible, it is hoped that modeling of the coronal field can improve our understanding of processes that drive the corona to flare and produce CMEs. Many coronal modeling efforts employ spectropolarimetric observations of the photosphere, which can be used to infer magnetic fields and flows there; the model then relates these photospheric measurements to coronal currents. Observations of coronal emission structures might also usefully inform coronal field models. Here, I will discuss different approaches to modeling the coronal magnetic field, using both photospheric and other data sets, and possible roles for data assimilation. Title: Can we Determine Electric Fields and Poynting Fluxes from Vector Magnetograms and Doppler Measurements? Authors: Fisher, G. H.; Welsch, B. T.; Abbett, W. P. Bibcode: 2011AGUFMSH33C..07F Altcode: The availability of vector magnetogram sequences with sufficient accuracy and cadence to estimate the time derivative of the magnetic field allows us to use Faraday's law to find an approximate solution for the electric field in the photosphere, using a Poloidal-Toroidal Decomposition (PTD) of the magnetic field and its partial time derivative. Without additional information, however, the electric field found from this technique is under-determined -- Faraday's law provides no information about the electric field that can be derived the gradient of a scalar potential. Here, we show how additional information in the form of line-of-sight Doppler flow measurements, and motions transverse to the line-of-sight determined with ad-hoc methods such as local correlation tracking, can be combined with the PTD solutions to provide much more accurate solutions for the solar electric field, and therefore the Poynting flux of electromagnetic energy in the solar photosphere. Reliable, accurate maps of the Poynting flux are essential for quantitative studies of the buildup of magnetic energy before flares and coronal mass ejections. This work was supported by the NASA Heliophysics Theory Program, the NASA Living-With-a-Star Program, and the NSF Geosciences Directorate Title: Decorrelation Times of Photospheric Fields and Flows Authors: Welsch, B. T.; Kusano, K.; Yamamoto, T. T.; Fisher, G. H. Bibcode: 2011AGUFMSH31A1989W Altcode: We use autocorrelation to investigate evolution in flow fields inferred by applying Fourier Local Correlation Tracking (FLCT) to a sequence of high-resolution (0.3''), high-cadence (≃ 2 min.) line-of-sight magnetograms of NOAA AR 10930 recorded by SOT/NFI aboard the Hinode satellite over 12-13 December 2006. To baseline the timescales of flow evolution, we also autocorrelated the magnetograms, at several spatial binnings, to characterize the lifetimes of active region magnetic structure as a function of spatial scale. Autocorrelation of flow maps can be used to optimize tracking parameters, to understand tracking algorithms' susceptibility to noise, and to estimate flow lifetimes. Tracking parameters varied include: time interval Δ t between magnetogram pairs tracked; spatial binning applied to the magnetograms; and windowing parameter σ used in FLCT. In addition, we tracked both boxcar-averaged and unaveraged magnetograms. Because flow structures are thought to vary over a range of spatial and temporal scales in the photospheric plasma (including unresolved scales), we suggest that estimated flows necessarily represent a local average of the flow pattern over space and time, and argue that flow decorrelation times should be at least as long as Δ t to meaningfully estimate plasma velocities. When Δ t exceeds the flow decorrelation time, then displacements inferred from tracking represent the average velocity over more than one flow lifetime. We also analyze decorrelation times of flow components, divergences, and curls as functions of spatial scale and magnetic field strength. Title: Evolution and Activity of Solar Active Regions with STEREO Full Sun Imaging Authors: Li, Y.; Welsch, B. T.; Lynch, B. J.; Luhmann, J. G.; Fisher, G. H. Bibcode: 2011AGUFMSH13A1927L Altcode: Solar active regions emerge from the interior of the Sun. It is believed that the solar dynamo at the shear layer at the bottom of the convection zone generates flux ropes, which emerge to the photosphere as active regions. The active regions emerge with stressed and concentrated magnetic field up to a few thousand Gauss. Following the emerging phase, the field evolves and decays. The decay process of active regions is not fully understood. Active regions usually have multiple flares and CMEs. Solar eruptions consume magnetic free energy in active regions and eject field and mass away from the Sun. Solar eruptions may play a role in the decay of the magnetic field in active regions. The lifetime of active regions range from hours to perhaps a few months. Stronger active regions usually live longer than the earth view pass. We had always a single view of the Sun before STEREO. Using the full sun imaging of the STEREO mission, we study a few recent active regions on the rise phase of solar cycle 24. When the regions are in earth view, we analyze HMI magnetograms for the field and energy evolution. By observing the total number of flares and CMEs from each region using STEREO coronal images, we estimate the released energy through the lifetime of these active regions. We discuss the implications to active region energy budget and active region decay. Title: Numerical Simulation of a "Stealth" CME: Why Slow and Simple is Not Mysterious Authors: Lynch, B. J.; Li, Y.; Antiochos, S. K.; DeVore, C. R.; Luhmann, J. G.; Fisher, G. H. Bibcode: 2011AGUFMSH43A1937L Altcode: The stereoscopic viewing and improvements in coronagraph observations by STEREO/SECCHI and low corona EUV and X-ray observations at multiple wavelengths by STEREO, Hinode, and SDO -- combined with this solar minimum's exceptionally low activity -- have given rise to the community's interest in so-called "stealth" CMEs. A "stealth" CME is one in which there are almost no low coronal signatures of the CME eruption but often a very well resolved slow, flux-rope like eruption seen in the coronagraph data. The fact that the in situ observations of "stealth" CMEs have shown many of the signatures of magnetic clouds (including the interplanetary flux rope structure) poses the question, "Just how different these events are from normal CMEs?" We present a 3D numerical MHD simulation of the 2008 Jun 2 gradual streamer blowout CME which had virtually no identifiable low coronal signatures. We energize the field by simple footpoint shearing along the source region's polarity inversion line (PIL) and model the background solar wind structure using an ~2MK isothermal wind and a low-order PFSS representation of the CR2070 synoptic magnetogram. Our results will show that the CME "initiation" is obtained by slowly disrupting the quasi-steady-state configuration of the helmet streamer, resulting in the standard eruptive flare picture (albeit, on a large scale) that ejects the sheared fields and lowers the magnetic energy stored in filament channel. We obtain a relatively slow CME eruption and argue that these "stealth" CMEs are no different than the standard quasi-2D picture but are simply at the low end of the CME energy distribution. We will show preliminary comparisons between the simulation results and the coronagraph observations of the low coronal evolution of the CME. Title: Observational Analysis of Photospheric Magnetic Field Restructuring During Energetic Solar Flares Authors: Alvarado, J. D.; Buitrago, J. C.; Martinez Oliveros, J.; Lindsey, C. A.; Abbett, W. P.; Fisher, G. H. Bibcode: 2011AGUFMSH13B1944A Altcode: The magnetic field has proven to be the main driver in the behavior, dynamics and evolution of several solar atmospheric phenomena including sunspots, plages, faculae, CME's and flares. Observational evidence of photospheric magnetic field restructuring during energetic flares have shown an enhancement of the transversal field component suggesting an apparent relation between this process with the generation of ``sunquakes'', expanding ripples on the solar photosphere as a result of the momentum-energy transfer into the solar photosphere and subphotosphere. In this work we present a doppler and magnetic observational study of some recent energetic flaring events (X and M type of the 24th solar cycle) trying to find possible acoustic signatures and make a characterization of the photospheric magnetic field evolution during those flares, being this the observational basis of a future numerical modeling of the field restructuring during this phenomenon. Title: Momentum Balance in Eruptive Solar Flares: The Lorentz Force Acting on the Solar Atmosphere and the Solar Interior Authors: Fisher, George H.; Bercik, David J.; Welsch, Brian T.; Hudson, Hugh S. Bibcode: 2011sdmi.confE...9F Altcode: We compute the change in the Lorentz force integrated over the outer solar atmosphere implied by observed changes in vector magnetograms that occur during large, eruptive solar flares. This force perturbation should be balanced by an equal and opposite force perturbation acting on the solar photosphere and solar interior. The resulting expression for the estimated force change in the solar interior generalizes the earlier expression presented by Hudson, Fisher & Welsch (2008), providing horizontal as well as vertical force components, and provides a more accurate result for the vertical component of the perturbed force. We show that magnetic eruptions should result in the magnetic field at the photosphere becoming more horizontal, and hence should result in a downward (towards the solar interior) force change acting on the photosphere and solar interior, as recently argued from an analysis of magnetogram data by Wang & Liu. We suggest that there should be an observational relationship between the force change computed from changes in the vector magnetograms, the outward momentum carried by the ejecta from the flare, and the amplitude of the helioseismic disturbance driven by the downward force change. We use the impulse driven by the Lorentz force change in the outer solar atmosphere to derive an upper limit to the mass of erupting plasma that can escape from the Sun. Finally, we compare the expected Lorentz force change at the photosphere with simple estimates from flare-driven gasdynamic disturbances and from an estimate of the perturbed pressure from radiative backwarming of the photosphere in flaring conditions. Title: Radiative Cooling in MHD Models of the Quiet Sun Convection Zone and Corona Authors: Abbett, William; Fisher, George Bibcode: 2011shin.confE..10A Altcode: We present a series of numerical simulations of the quiet Sun plasma threaded by magnetic fields that extend from the upper convection zone into the low corona. We discuss an efficient, simplified approximation to the physics of optically thick radiative transport through the surface layers, and investigate the effects of convective turbulence on the magnetic structure of the Sun's atmosphere in an initially unipolar (open field) region. We find that the net Poynting flux below the surface is on average directed toward the interior, while in the photosphere and chromosphere the net flow of electromagnetic energy is outward into the solar corona. Overturning convective motions between these layers driven by rapid radiative cooling appears to be the source of energy for the oppositely directed fluxes of electromagnetic energy.