Author name code: fox
ADS astronomy entries on 2022-09-14
author:"Fox, Peter"
------------------------------------------------------------------------
Title: A Next-Generation Liquid Xenon Observatory for Dark Matter
and Neutrino Physics
Authors: Aalbers, J.; Abe, K.; Aerne, V.; Agostini, F.; Maouloud,
S. Ahmed; Akerib, D. S.; Akimov, D. Yu.; Akshat, J.; Al Musalhi, A. K.;
Alder, F.; Alsum, S. K.; Althueser, L.; Amarasinghe, C. S.; Amaro,
F. D.; Ames, A.; Anderson, T. J.; Andrieu, B.; Angelides, N.; Angelino,
E.; Angevaare, J.; Antochi, V. C.; Antón Martin, D.; Antunovic, B.;
Aprile, E.; Araújo, H. M.; Armstrong, J. E.; Arneodo, F.; Arthurs,
M.; Asadi, P.; Baek, S.; Bai, X.; Bajpai, D.; Baker, A.; Balajthy, J.;
Balashov, S.; Balzer, M.; Bandyopadhyay, A.; Bang, J.; Barberio, E.;
Bargemann, J. W.; Baudis, L.; Bauer, D.; Baur, D.; Baxter, A.; Baxter,
A. L.; Bazyk, M.; Beattie, K.; Behrens, J.; Bell, N. F.; Bellagamba,
L.; Beltrame, P.; Benabderrahmane, M.; Bernard, E. P.; Bertone,
G. F.; Bhattacharjee, P.; Bhatti, A.; Biekert, A.; Biesiadzinski,
T. P.; Binau, A. R.; Biondi, R.; Biondi, Y.; Birch, H. J.; Bishara,
F.; Bismark, A.; Blanco, C.; Blockinger, G. M.; Bodnia, E.; Boehm,
C.; Bolozdynya, A. I.; Bolton, P. D.; Bottaro, S.; Bourgeois, C.;
Boxer, B.; Brás, P.; Breskin, A.; Breur, P. A.; Brew, C. A. J.;
Brod, J.; Brookes, E.; Brown, A.; Brown, E.; Bruenner, S.; Bruno,
G.; Budnik, R.; Bui, T. K.; Burdin, S.; Buse, S.; Busenitz, J. K.;
Buttazzo, D.; Buuck, M.; Buzulutskov, A.; Cabrita, R.; Cai, C.; Cai,
D.; Capelli, C.; Cardoso, J. M. R.; Carmona-Benitez, M. C.; Cascella,
M.; Catena, R.; Chakraborty, S.; Chan, C.; Chang, S.; Chauvin, A.;
Chawla, A.; Chen, H.; Chepel, V.; Chott, N. I.; Cichon, D.; Cimental
Chavez, A.; Cimmino, B.; Clark, M.; Co, R. T.; Colijn, A. P.; Conrad,
J.; Converse, M. V.; Costa, M.; Cottle, A.; Cox, G.; Creaner, O.;
Cuenca Garcia, J. J.; Cussonneau, J. P.; Cutter, J. E.; Dahl, C. E.;
D'Andrea, V.; David, A.; Decowski, M. P.; Dent, J. B.; Deppisch,
F. F.; de Viveiros, L.; Di Gangi, P.; Di Giovanni, A.; Di Pede, S.;
Dierle, J.; Diglio, S.; Dobson, J. E. Y.; Doerenkamp, M.; Douillet,
D.; Drexlin, G.; Druszkiewicz, E.; Dunsky, D.; Eitel, K.; Elykov, A.;
Emken, T.; Engel, R.; Eriksen, S. R.; Fairbairn, M.; Fan, A.; Fan,
J. J.; Farrell, S. J.; Fayer, S.; Fearon, N. M.; Ferella, A.; Ferrari,
C.; Fieguth, A.; Fieguth, A.; Fiorucci, S.; Fischer, H.; Flaecher,
H.; Flierman, M.; Florek, T.; Foot, R.; Fox, P. J.; Franceschini,
R.; Fraser, E. D.; Frenk, C. S.; Frohlich, S.; Fruth, T.; Fulgione,
W.; Fuselli, C.; Gaemers, P.; Gaior, R.; Gaitskell, R. J.; Galloway,
M.; Gao, F.; Garcia Garcia, I.; Genovesi, J.; Ghag, C.; Ghosh, S.;
Gibson, E.; Gil, W.; Giovagnoli, D.; Girard, F.; Glade-Beucke, R.;
Glück, F.; Gokhale, S.; de Gouvêa, A.; Gráf, L.; Grandi, L.; Grigat,
J.; Grinstein, B.; van der Grinten, M. G. D.; Grössle, R.; Guan, H.;
Guida, M.; Gumbsheimer, R.; Gwilliam, C. B.; Hall, C. R.; Hall, L. J.;
Hammann, R.; Han, K.; Hannen, V.; Hansmann-Menzemer, S.; Harata,
R.; Hardin, S. P.; Hardy, E.; Hardy, C. A.; Harigaya, K.; Harnik,
R.; Haselschwardt, S. J.; Hernandez, M.; Hertel, S. A.; Higuera,
A.; Hils, C.; Hochrein, S.; Hoetzsch, L.; Hoferichter, M.; Hood, N.;
Hooper, D.; Horn, M.; Howlett, J.; Huang, D. Q.; Huang, Y.; Hunt, D.;
Iacovacci, M.; Iaquaniello, G.; Ide, R.; Ignarra, C. M.; Iloglu, G.;
Itow, Y.; Jacquet, E.; Jahangir, O.; Jakob, J.; James, R. S.; Jansen,
A.; Ji, W.; Ji, X.; Joerg, F.; Johnson, J.; Joy, A.; Kaboth, A. C.;
Kamaha, A. C.; Kanezaki, K.; Kar, K.; Kara, M.; Kato, N.; Kavrigin,
P.; Kazama, S.; Keaveney, A. W.; Kellerer, J.; Khaitan, D.; Khazov,
A.; Khundzakishvili, G.; Khurana, I.; Kilminster, B.; Kleifges, M.;
Ko, P.; Kobayashi, M.; Kobayashi, M.; Kodroff, D.; Koltmann, G.;
Kopec, A.; Kopmann, A.; Kopp, J.; Korley, L.; Kornoukhov, V. N.;
Korolkova, E. V.; Kraus, H.; Krauss, L. M.; Kravitz, S.; Kreczko,
L.; Kudryavtsev, V. A.; Kuger, F.; Kumar, J.; López Paredes, B.;
LaCascio, L.; Laine, Q.; Landsman, H.; Lang, R. F.; Leason, E. A.;
Lee, J.; Leonard, D. S.; Lesko, K. T.; Levinson, L.; Levy, C.; Li,
I.; Li, S. C.; Li, T.; Liang, S.; Liebenthal, C. S.; Lin, J.; Lin,
Q.; Lindemann, S.; Lindner, M.; Lindote, A.; Linehan, R.; Lippincott,
W. H.; Liu, X.; Liu, K.; Liu, J.; Loizeau, J.; Lombardi, F.; Long,
J.; Lopes, M. I.; Lopez Asamar, E.; Lorenzon, W.; Lu, C.; Luitz, S.;
Ma, Y.; Machado, P. A. N.; Macolino, C.; Maeda, T.; Mahlstedt, J.;
Majewski, P. A.; Manalaysay, A.; Mancuso, A.; Manenti, L.; Manfredini,
A.; Mannino, R. L.; Marangou, N.; March-Russell, J.; Marignetti, F.;
Marrodán Undagoitia, T.; Martens, K.; Martin, R.; Martinez-Soler,
I.; Masbou, J.; Masson, D.; Masson, E.; Mastroianni, S.; Mastronardi,
M.; Matias-Lopes, J. A.; McCarthy, M. E.; McFadden, N.; McGinness,
E.; McKinsey, D. N.; McLaughlin, J.; McMichael, K.; Meinhardt, P.;
Menéndez, J.; Meng, Y.; Messina, M.; Midha, R.; Milisavljevic, D.;
Miller, E. H.; Milosevic, B.; Milutinovic, S.; Mitra, S. A.; Miuchi,
K.; Mizrachi, E.; Mizukoshi, K.; Molinario, A.; Monte, A.; Monteiro,
C. M. B.; Monzani, M. E.; Moore, J. S.; Morå, K.; Morad, J. A.;
Morales Mendoza, J. D.; Moriyama, S.; Morrison, E.; Morteau, E.;
Mosbacher, Y.; Mount, B. J.; Mueller, J.; Murphy, A. St. J.; Murra,
M.; Naim, D.; Nakamura, S.; Nash, E.; Navaieelavasani, N.; Naylor,
A.; Nedlik, C.; Nelson, H. N.; Neves, F.; Newstead, J. L.; Ni, K.;
Nikoleyczik, J. A.; Niro, V.; Oberlack, U. G.; Obradovic, M.; Odgers,
K.; O'Hare, C. A. J.; Oikonomou, P.; Olcina, I.; Oliver-Mallory, K.;
Oranday, A.; Orpwood, J.; Ostrovskiy, I.; Ozaki, K.; Paetsch, B.; Pal,
S.; Palacio, J.; Palladino, K. J.; Palmer, J.; Panci, P.; Pandurovic,
M.; Parlati, A.; Parveen, N.; Patton, S. J.; Pěč, V.; Pellegrini,
Q.; Penning, B.; Pereira, G.; Peres, R.; Perez-Gonzalez, Y.; Perry, E.;
Pershing, T.; Petrossian-Byrne, R.; Pienaar, J.; Piepke, A.; Pieramico,
G.; Pierre, M.; Piotter, M.; Pizella, V.; Plante, G.; Pollmann, T.;
Porzio, D.; Qi, J.; Qie, Y.; Qin, J.; Raj, N.; Rajado Silva, M.;
Ramanathan, K.; Ramírez García, D.; Ravanis, J.; Redard-Jacot, L.;
Redigolo, D.; Reichard, S.; Reichenbacher, J.; Rhyne, C. A.; Richards,
A.; Riffard, Q.; Rischbieter, G. R. C.; Rocchetti, A.; Rosenfeld,
S. L.; Rosero, R.; Rupp, N.; Rushton, T.; Saha, S.; Sanchez, L.;
Sanchez-Lucas, P.; Santone, D.; dos Santos, J. M. F.; Sarnoff,
I.; Sartorelli, G.; Sazzad, A. B. M. R.; Scheibelhut, M.; Schnee,
R. W.; Schrank, M.; Schreiner, J.; Schulte, P.; Schulte, D.; Schulze
Eissing, H.; Schumann, M.; Schwemberger, T.; Schwenk, A.; Schwetz,
T.; Scotto Lavina, L.; Scovell, P. R.; Sekiya, H.; Selvi, M.; Semenov,
E.; Semeria, F.; Shagin, P.; Shaw, S.; Shi, S.; Shockley, E.; Shutt,
T. A.; Si-Ahmed, R.; Silk, J. J.; Silva, C.; Silva, M. C.; Simgen, H.;
Šimkovic, F.; Sinev, G.; Singh, R.; Skulski, W.; Smirnov, J.; Smith,
R.; Solmaz, M.; Solovov, V. N.; Sorensen, P.; Soria, J.; Sparmann,
T. J.; Stancu, I.; Steidl, M.; Stevens, A.; Stifter, K.; Strigari,
L. E.; Subotic, D.; Suerfu, B.; Suliga, A. M.; Sumner, T. J.; Szabo,
P.; Szydagis, M.; Takeda, A.; Takeuchi, Y.; Tan, P. -L.; Taricco, C.;
Taylor, W. C.; Temples, D. J.; Terliuk, A.; Terman, P. A.; Thers,
D.; Thieme, K.; Thümmler, Th.; Tiedt, D. R.; Timalsina, M.; To,
W. H.; Toennies, F.; Tong, Z.; Toschi, F.; Tovey, D. R.; Tranter, J.;
Trask, M.; Trinchero, G. C.; Tripathi, M.; Tronstad, D. R.; Trotta,
R.; Tsai, Y. D.; Tunnell, C. D.; Turner, W. G.; Ueno, R.; Urquijo,
P.; Utku, U.; Vaitkus, A.; Valerius, K.; Vassilev, E.; Vecchi, S.;
Velan, V.; Vetter, S.; Vincent, A. C.; Vittorio, L.; Volta, G.;
von Krosigk, B.; von Piechowski, M.; Vorkapic, D.; Wagner, C. E. M.;
Wang, A. M.; Wang, B.; Wang, Y.; Wang, W.; Wang, J. J.; Wang, L. -T.;
Wang, M.; Wang, Y.; Watson, J. R.; Wei, Y.; Weinheimer, C.; Weisman,
E.; Weiss, M.; Wenz, D.; West, S. M.; Whitis, T. J.; Williams, M.;
Wilson, M. J.; Winkler, D.; Wittweg, C.; Wolf, J.; Wolf, T.; Wolfs,
F. L. H.; Woodford, S.; Woodward, D.; Wright, C. J.; Wu, V. H. S.;
Wu, P.; Wüstling, S.; Wurm, M.; Xia, Q.; Xiang, X.; Xing, Y.; Xu,
J.; Xu, Z.; Xu, D.; Yamashita, M.; Yamazaki, R.; Yan, H.; Yang, L.;
Yang, Y.; Ye, J.; Yeh, M.; Young, I.; Yu, H. B.; Yu, T. T.; Yuan, L.;
Zavattini, G.; Zerbo, S.; Zhang, Y.; Zhong, M.; Zhou, N.; Zhou, X.;
Zhu, T.; Zhu, Y.; Zhuang, Y.; Zopounidis, J. P.; Zuber, K.; Zupan, J.
Bibcode: 2022arXiv220302309A
Altcode:
The nature of dark matter and properties of neutrinos are among the
most pressing issues in contemporary particle physics. The dual-phase
xenon time-projection chamber is the leading technology to cover the
available parameter space for Weakly Interacting Massive Particles
(WIMPs), while featuring extensive sensitivity to many alternative dark
matter candidates. These detectors can also study neutrinos through
neutrinoless double-beta decay and through a variety of astrophysical
sources. A next-generation xenon-based detector will therefore be a true
multi-purpose observatory to significantly advance particle physics,
nuclear physics, astrophysics, solar physics, and cosmology. This
review article presents the science cases for such a detector.
Title: Methods and results of truly interdisciplinary data discovery
Authors: Eleish, Ahmed; Duerr, Ruth; Parsons, Mark; Bugbee, Kaylin;
Foshee, Emily; Acharya, Ashish; Berrios, Daniel; Bitner, David;
Fox, Peter
Bibcode: 2021AGUFMIN23B..09E
Altcode:
A fundamental first step of interdisciplinary science is finding
data from multiple disciplines. This remains a significant challenge
because of the many different ways disciplines conceive of and
represent information. NASA is facing this challenge head on in its
data strategy by calling for a data discovery system that reaches
across all NASA disciplines exploring the farthest reaches of space
down to the genomics of our own planet. This has proven to be a very
challenging task, but a multifaceted approach using modern informatics
methods has demonstrated initial success. We explicitly implement formal
information modeling, use-case requirements development, and formal
and informal community and institutional development. We began with an
in-depth landscape analysis by modeling how the many different NASA
systems present their data, by capturing the definitions of concepts
that can vary widely in meaning across disciplines, and by cataloging
the data services and standards that NASA deploys. This led to an
initial information model that harmonized terms across NASA while
maintaining their discipline specific meaning. We then developed two
very specific, but interdisciplinary, use cases through an established
iterative methodology. The first use case examined the effects of
solar particle events on living organisms; the second compared Earth
and other planetary atmospheres. The derived requirements enhanced the
information model and led to the development of functional prototypes. A
working group with representatives from all of NASAs five science
divisions has guided the overall process. This provides the critical
social glue that allows the technical systems to truly function. The
group has continually helped define the scope, identify relevant use
cases and requirements, and develop the institutional processes and
buy-in necessary to ensure ongoing success. Results of this work can
inform the development of similarly ambitious frameworks and systems,
while also informing the basic pragmatics of informatics.
Title: Mineral Informatics: Analysis and Visualization of Minerals
through Time and Space
Authors: Hazen, Robert; Morrison, Shaunna; Williams, Jason; Prabhu,
Anirudh; Eleish, Ahmed; Fox, Peter
Bibcode: 2021AGUFMIN13A..01H
Altcode:
Minerals provide the most robust, information-rich artifacts of
planetary origins and evolution. Each mineral specimen is a time
capsule that preserves a record of successive chemical, physical,
and ultimately biological environments. If we are to understand the
4.5-billion-year story of Earth and its neighboring planets and moons,
then minerals hold the most eloquent testimony of deep time and epic
change. Mineral classification is provided by rigorous protocols
of the IMA-CNMNC [1]. Each mineral species owes its identity to
its unique combination of idealized end-member composition and/or
chemical range, plus idealized crystal structure. In this regard,
the IMA-CNMNC approach employs the minimum information necessary to
unambiguously define each species. More than 5700 species have been
approved, while thousands more potential species await discovery and
description. However, these criteria do not lend themselves to an
exploration of planetary evolution, nor are the idealizations that
define IMA species equivalent to mineral natural kinds that represent
genuine divisions of nature. We propose a complementary evolutionary
system of mineralogy that strives to define mineral natural kinds based
on their positions in the evolutionary chronology of a planet, and the
process by which they formed. In this system, each mineral natural kind
has a distinctive temporal and paragenetic context, as manifest in its
unique combination of chemical, structural, physical, and contextual
attributes. The evolutionary system is thus data intensive, embracing
all of a minerals attributes in identifying natural kinds, for example
through cluster analysis [2,3]. Studies of all known minerals and their
paragenetic modes suggest that more than 10,000 mineral natural kinds
exist, many of which relate to IMA-approved species by lumping and/or
splitting criteria [4]. Analytical and visualization methods applied
to mineral data reveal striking temporal and spatial trends across the
Mineral Kingdom. The bipartite network graph shows 5659 blue nodes
representing mineral species linked to 57 green nodes representing
different formation processes. [1] Hawthorne et al. (2021) Min. Mag. 85,
125; [2] Hazen & Morrison (2021) Am.Min. 106, in press; [3] Hazen
(2019) Ibid. 104, 468; [4] Hazen & Morrison (2022) Ibid. 107,
in press.
Title: Reimagining Origins of Life Research: Innovation and Synthesis
via Experimentation, Instrumentation, and Data Analytics
Authors: Rogers, Karyn; Pedreira-Segade, Ulysse; Fox, Peter; Shelley,
Jacob T.; Steele, Andrew; Trail, Dustin
Bibcode: 2021BAAS...53d.215R
Altcode: 2021psad.rept..215R
Life's origin is one of the most compelling questions, yet synergy
between prebiotic chemistry and geology remains elusive. Experimental,
instrumental, and data science innovations are poised to propel the
origins community toward integration, consensus, and a central role in
the next decade of NASA's Planetary Science and Astrobiology portfolio.
Title: Thank You to Our 2020 Reviewers
Authors: Fox, Peter A.; Altintas, Ilkay; Diviacco, Paolo; Donnellan,
Andrea; Gentemann, Chelle; Glaves, Helen M.; Jiang, Jonathan H.;
Maute, Astrid; Pirenne, Benoit; Tiampo, Kristy
Bibcode: 2021E&SS....801735F
Altcode:
No abstract at ADS
Title: Affinity analysis of mineral co-occurrence: Predicting unknown
mineral occurrences with machine learning
Authors: Morrison, S. M.; Prabhu, A.; Eleish, A.; Narkar, S.; Fox,
P. A.; Golden, J. J.; Downs, R. T.; Perry, S.; Burns, P. C.; Ralph,
J.; Hazen, R. M.
Bibcode: 2020AGUFMED0440001M
Altcode:
The expansion of mineralogical data resources facilitates the
development of predictive methods, such as affinity analysis [1],
that identify the location of previously unknown mineral occurrences,
deposits or geologic environments, as well as the probabilistic
prediction of the likely mineral inventory at any given locality on
Earth's surface or, where suitable data is available, other planetary
bodies. Mineral Affinity Analysis [2-3] can be used to answer many
questions of scientific interest. The most basic application of mineral
association rules is to identify the most likely location to find a
new occurrence of a specific mineral species, with various probability
metrics. This can be expanded to identify the most likely location to
find a mineral assemblage - an assemblage that could correspond to a
certain geologic setting, planetary environment, or deposit type. This
will allow researchers interested in locating planetary analogy sites,
exploring and assessing resources, or even simply collecting mineral
specimens to identify locations that are not currently known to have
the mineral or mineral assemblage of interest, but are likely to. This
method goes well beyond querying a database to find a match to a list
of minerals - it predicts previously unknown information. Furthermore,
researchers can use this recommender system to predict what minerals
are likely to occur at a specific location of interest. This has
a broad range of applicability, from predicting which rare mineral
species, indicative of certain planetary conditions or history, are
likely to occur on the surface of Mars based on the broad mineralogy
detected by remote sensing to predicting the full mineral inventory
for mineral collectors who focus on particular localities. [1]
Brin S, Motwani R, Silverstein C (1997) Beyond Market Baskets, ACM
SIGMOD Record. [2] Prabhu et al. (2019) Predicting unknown mineral
localities based on mineral associations, AGU, Abstract EP23D-2286 [3] Morrison SM, Prabhu A, Eleish A, Narkar S, Fox P, Golden JJ,
Downs RT, Perry S, Burns PC, Ralph J & Hazen RM (2020) Mineral
Affinity Analysis: Predicting Unknown Mineral Occurrences with Machine
Learning, Goldschmidt annual meeting (virtual)
Title: Thank You to Our 2019 Reviewers
Authors: Fox, Peter A.; Diviacco, Paolo; Donnellan, Andrea; Glaves,
Helen M.; Jiang, Jonathan H.; Maute, Astrid; Pirenne, Benoit; Tiampo,
Kristy; Vernon, Frank
Bibcode: 2020E&SS....701195F
Altcode:
No abstract at ADS
Title: Predicting Multi-Component Mineral Compositions in Gale crater,
Mars with Label Distribution Learning
Authors: Morrison, S. M.; Pan, F.; Gagné, O. C.; Prabhu, A.; Eleish,
A.; Fox, P. A.; Downs, R. T.; Bristow, T.; Rampe, E. B.; Blake,
D. F.; Vaniman, D.; Achilles, C.; Ming, D. W.; Yen, A.; Treiman,
A. H.; Morris, R. V.; Chipera, S.; Craig, P.; Tu, V.; Castle, N.;
Sarrazin, P.; Des Marais, D. J.; Hazen, R.
Bibcode: 2018AGUFM.P21I3438M
Altcode:
The CheMin X-ray diffraction (XRD) instrument onboard the Mars Science
Laboratory rover Curiosity analyzes drilled rock fines and scooped soils
in Gale crater, Mars. The CheMin team estimates mineral abundances and
unit-cell parameters of major crystalline phases found in each of the
CheMin samples with Rietveld refinement of the XRD patterns. The main
crystalline phases identified by CheMin include plagioclase, sanidine,
pyroxenes, olivine, magnetite, and alunite-jarosite group minerals. In
order to better understand the formational conditions and geologic
history of the minerals found in Gale crater, the CheMin team developed
a crystal-chemical method to predict limited chemical compositions of
the minerals observed in the CheMin samples [1,2]. However, limitations
in the statistical algorithms inhibited the prediction of chemical
compositions beyond three elements. In this study, we adapt a machine
learning technique, Label Distribution Learning (LDL) [3], to predict
multicomponent chemical compositions of Gale crater mineral phases,
thereby allowing for more detailed petrologic interpretation of the
geologic history of the martian surface. LDL is a novel framework
for classification problems with small datasets and has been widely
applied to facial recognition problems such as age estimation. In this
study, we adapt the LDL algorithm such that it can predict chemical
elements (labels) and their abundances (degrees) for each martian
mineral sample, based on crystallographic parameters. We evaluate
performance using distance and similarity between label distributions
as well as mean square error and also compare the results to
traditional machine learning methods. [1] Morrison et al. (2017) Relationships
between unit-cell parameters and composition for rock-forming
minerals on Earth, Mars, and other extraterrestrial
bodies, Am Min, 103(6): 848-856 [2] Morrison et al (2017) Crystal
chemistry of martian minerals from Bradbury Landing
through Naukluft Plateau, Gale crater, Mars,
Am Min, 103(6): 857-871 [3] Geng (2016) Label
distribution learning. IEEE Transactions on Knowledge and Data
Engineering, 28(7), 1734-1748
Title: TASI Lectures on WIMPs and Supersymmetry
Authors: Fox, P. J.
Bibcode: 2018tasi.confE...5F
Altcode: 2018PoS...333E...5F
No abstract at ADS
Title: Quantifying ecological impacts of mass extinctions with
network analysis of fossil communities
Authors: Muscente, A. D.; Prabhu, Anirudh; Zhong, Hao; Eleish, Ahmed;
Meyer, Michael B.; Fox, Peter; Hazen, Robert M.; Knoll, Andrew H.
Bibcode: 2018PNAS..115.5217M
Altcode:
Mass extinctions documented by the fossil record provide critical
benchmarks for assessing changes through time in biodiversity and
ecology. Efforts to compare biotic crises of the past and present,
however, encounter difficulty because taxonomic and ecological changes
are decoupled, and although various metrics exist for describing
taxonomic turnover, no methods have yet been proposed to quantify
the ecological impacts of extinction events. To address this issue,
we apply a network-based approach to exploring the evolution of
marine animal communities over the Phanerozoic Eon. Network analysis
of fossil co-occurrence data enables us to identify nonrandom
associations of interrelated paleocommunities. These associations,
or evolutionary paleocommunities, dominated total diversity during
successive intervals of relative community stasis. Community
turnover occurred largely during mass extinctions and radiations,
when ecological reorganization resulted in the decline of one
association and the rise of another. Altogether, we identify five
evolutionary paleocommunities at the generic and familial levels in
addition to three ordinal associations that correspond to Sepkoski's
Cambrian, Paleozoic, and Modern evolutionary faunas. In this context,
we quantify magnitudes of ecological change by measuring shifts in
the representation of evolutionary paleocommunities over geologic
time. Our work shows that the Great Ordovician Biodiversification
Event had the largest effect on ecology, followed in descending
order by the Permian-Triassic, Cretaceous-Paleogene, Devonian, and
Triassic-Jurassic mass extinctions. Despite its taxonomic severity,
the Ordovician extinction did not strongly affect co-occurrences of
taxa, affirming its limited ecological impact. Network paleoecology
offers promising approaches to exploring ecological consequences of
extinctions and radiations.
Title: Magnetometer Data for the Ages: Achieving complete FGM
instrument coverage of the multi-spacecraft Cluster mission (2000
to 2015+)
Authors: Alconcel, Leah-Nani; Fox, Peter; Colgan, Cary; Oddy, Tim;
Brown, Patrick; Carr, Chris
Bibcode: 2016EGUGA..18.1798A
Altcode:
The calibrated dataset from the Cluster magnetometer instruments
(FGMs) aboard the four Cluster spacecraft comprises an invaluable
contribution to magnetospheric physics. It is also essential for the
derivation of some datasets from other instruments, all of which have
been made available through ESA's Cluster Science Archive (CSA). The
FGM team at Imperial College - the PI institute that built and supports
operation of the magnetometers - has regularly provided validated
data to the CSA since its inception. Now that other multi-spacecraft
missions such as the Magnetospheric Multiscale Mission (MMS) have
come online, it will be possible to make inter-mission as well as
inter-spacecraft comparisons. The FGM team hopes to enable those
comparisons by delivering magnetic field data from periods when the
Cluster spacecraft are not otherwise taking science telemetry. These
periods are becoming more common as the spacecraft age. Accomplishing
this would also achieve near-complete magnetic field coverage throughout
the Cluster mission. Preparation of these data to archival standards
raises unusual challenges to be discussed in this presentation.
Title: The Evolution of Comet 67P as Seen by a Mass-Resolving Ion
Spectrometer
Authors: Stenberg Wieser, G.; Nilsson, H.; Behar, E.; Simon Wedlund,
C.; Kallio, E. J.; Gunell, H.; Edberg, N. J. T.; Eriksson, A. I.;
Yamauchi, M.; Koenders, C.; Wieser, M.; Lundin, R. N. A.; Mandt,
K.; Burch, J. L.; Goldstein, R.; Mokashi, P.; Carr, C.; Cupido, E.;
Fox, P. T.; Szego, K.; Nemeth, Z.; Fedorov, A.; Barbash, S.; Savaud,
J. A.; Koskinen, H. E. J.; Richter, I.; Lebreton, J. P.; Pierre, H.;
Volwerk, M.; Vallat, C.; Geiger, B.
Bibcode: 2015AGUFM.P31E2101S
Altcode:
We study comet 67P/Churyumov-Gerasimenko using the mass-resolving
ion spectrometer RPC-ICA (Rosetta Plasma Consortium-Ion Composition
Analyzer) onboard the Rosetta spacecraft. RPC-ICA measures both solar
wind ions and ions of cometary origin in the energy range 10 eV-40
keV with high angular resolution. We observe the evolution of the ion
environment close to the comet as the distance to the sun changes. At a
distance of 3.6 AU the instrument detects the first water ions from
the comet but the comet activity is still low and the solar wind
passes through the thin atmosphere without being much affected. The
situation gradually changes as the comet moves closer to the sun and
the cometary atmosphere develops. Mass loading becomes important,
the solar wind is deflected and large fluxes of accelerated cometary
ions are observed. We characterize the changes of the ion environment
in terms of ion fluxes and energy spectra as the comet moves from
3.6 AU through perihelion. We look at both long-term and short-term
variations and investigate which timescales are important.
Title: Evolution of the ion environment of comet
67P/Churyumov-Gerasimenko. Observations between 3.6 and 2.0 AU
Authors: Nilsson, H.; Stenberg Wieser, G.; Behar, E.; Simon Wedlund,
C.; Kallio, E.; Gunell, H.; Edberg, N. J. T.; Eriksson, A. I.;
Yamauchi, M.; Koenders, C.; Wieser, M.; Lundin, R.; Barabash, S.;
Mandt, K.; Burch, J. L.; Goldstein, R.; Mokashi, P.; Carr, C.; Cupido,
E.; Fox, P. T.; Szego, K.; Nemeth, Z.; Fedorov, A.; Sauvaud, J. -A.;
Koskinen, H.; Richter, I.; Lebreton, J. -P.; Henri, P.; Volwerk, M.;
Vallat, C.; Geiger, B.
Bibcode: 2015A&A...583A..20N
Altcode:
Context. The Rosetta spacecraft is escorting comet
67P/Churyumov-Gerasimenko from a heliocentric distance of >3.6
AU, where the comet activity was low, until perihelion at 1.24
AU. Initially, the solar wind permeates the thin comet atmosphere formed
from sublimation.
Aims: Using the Rosetta Plasma Consortium
Ion Composition Analyzer (RPC-ICA), we study the gradual evolution of
the comet ion environment, from the first detectable traces of water
ions to the stage where cometary water ions accelerated to about 1 keV
energy are abundant. We compare ion fluxes of solar wind and cometary
origin.
Methods: RPC-ICA is an ion mass spectrometer measuring
ions of solar wind and cometary origins in the 10 eV-40 keV energy
range.
Results: We show how the flux of accelerated water ions
with energies above 120 eV increases between 3.6 and 2.0 AU. The 24 h
average increases by 4 orders of magnitude, mainly because high-flux
periods become more common. The water ion energy spectra also become
broader with time. This may indicate a larger and more uniform source
region. At 2.0 AU the accelerated water ion flux is frequently of the
same order as the solar wind proton flux. Water ions of 120 eV-few keV
energy may thus constitute a significant part of the ions sputtering
the nucleus surface. The ion density and mass in the comet vicinity
is dominated by ions of cometary origin. The solar wind is deflected
and the energy spectra broadened compared to an undisturbed solar
wind.
Conclusions: The flux of accelerated water ions moving
from the upstream direction back toward the nucleus is a strongly
nonlinear function of the heliocentric distance.
Title: Integrated Payload Data Handling Demonstrator
Authors: FitzGeorge, T.; Wishart, A.; Hann, M.; Phan, N.; Carr, C. M.;
Cupido, E.; Fox, P.; Oddy, T.; McGregor, A.; Marshall, A.; Waltham, N.
Bibcode: 2013EPSC....8...57F
Altcode:
An integrated Payload Data Handling System (IPDHS) is one in which
multiple instruments share a central payload processor for their
on-board data processing tasks. This offers a number of advantages
over the conventional decentralised architecture. Savings in payload
mass and power can be realised because the total processing resource
is matched to the requirement, as opposed to the decentralised
architecture where the processing resource is in effect the sum of
all the applications. Overall development cost can be reduced using a
common processor. At individual instrument level the potential benefits
include a standardised application development environment, and the
opportunity to run the instrument data handling application on a fully
redundant and more powerful processor. This paper describes a joint
programme by Astrium Ltd, SCISYS UK Limited, Imperial College London
and RAL Space to implement a realistic demonstration of an I-PDHS using
engineering models of flight instruments (a magnetometer and a camera)
and a laboratory demonstrator of a central payload processor which
is functionally representative of a flight design. The objective is
to raise the Technology Readiness Level (TRL) of the centralised data
processing technique by addressing the key areas of task partitioning
to prevent fault propagation and the use of a common development
process for the instrument applications. The project is supported by
a UK Space Agency grant awarded under the National Space Technology
Programme SpaceCITI scheme. The demonstration system is set up at
the UK Space Agency's International Space Innovation Centre (ISIC)
at Harwell and makes use of the ISIC Concurrent Design Facility (CDF).
Title: Search for Dark Matter in Events with One Jet and Missing
Transverse Energy in pp¯ Collisions at s=1.96TeV
Authors: Aaltonen, T.; Álvarez González, B.; Amerio, S.; Amidei,
D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Appel,
J. A.; Arisawa, T.; Artikov, A.; Asaadi, J.; Ashmanskas, W.;
Auerbach, B.; Aurisano, A.; Azfar, F.; Badgett, W.; Bae, T.; Bai,
Y.; Barbaro-Galtieri, A.; Barnes, V. E.; Barnett, B. A.; Barria,
P.; Bartos, P.; Bauce, M.; Bedeschi, F.; Behari, S.; Bellettini,
G.; Bellinger, J.; Benjamin, D.; Beretvas, A.; Bhatti, A.; Bisello,
D.; Bizjak, I.; Bland, K. R.; Blumenfeld, B.; Bocci, A.; Bodek, A.;
Bortoletto, D.; Boudreau, J.; Boveia, A.; Brigliadori, L.; Bromberg,
C.; Brucken, E.; Budagov, J.; Budd, H. S.; Burkett, K.; Busetto,
G.; Bussey, P.; Buzatu, A.; Calamba, A.; Calancha, C.; Camarda, S.;
Campanelli, M.; Campbell, M.; Canelli, F.; Carls, B.; Carlsmith, D.;
Carosi, R.; Carrillo, S.; Carron, S.; Casal, B.; Casarsa, M.; Castro,
A.; Catastini, P.; Cauz, D.; Cavaliere, V.; Cavalli-Sforza, M.; Cerri,
A.; Cerrito, L.; Chen, Y. C.; Chertok, M.; Chiarelli, G.; Chlachidze,
G.; Chlebana, F.; Cho, K.; Chokheli, D.; Chung, W. H.; Chung, Y. S.;
Ciocci, M. A.; Clark, A.; Clarke, C.; Compostella, G.; Convery,
M. E.; Conway, J.; Corbo, M.; Cordelli, M.; Cox, C. A.; Cox, D. J.;
Crescioli, F.; Cuevas, J.; Culbertson, R.; Dagenhart, D.; d'Ascenzo,
N.; Datta, M.; de Barbaro, P.; Dell'Orso, M.; Demortier, L.; Deninno,
M.; Devoto, F.; d'Errico, M.; Di Canto, A.; Di Ruzza, B.; Dittmann,
J. R.; D'Onofrio, M.; Donati, S.; Dong, P.; Dorigo, M.; Dorigo, T.;
Ebina, K.; Elagin, A.; Eppig, A.; Erbacher, R.; Errede, S.; Ershaidat,
N.; Eusebi, R.; Farrington, S.; Feindt, M.; Fernandez, J. P.; Field,
R.; Flanagan, G.; Forrest, R.; Fox, P. J.; Frank, M. J.; Franklin, M.;
Freeman, J. C.; Funakoshi, Y.; Furic, I.; Gallinaro, M.; Garcia, J. E.;
Garfinkel, A. F.; Garosi, P.; Gerberich, H.; Gerchtein, E.; Giagu,
S.; Giakoumopoulou, V.; Giannetti, P.; Gibson, K.; Ginsburg, C. M.;
Giokaris, N.; Giromini, P.; Giurgiu, G.; Glagolev, V.; Glenzinski,
D.; Gold, M.; Goldin, D.; Goldschmidt, N.; Golossanov, A.; Gomez,
G.; Gomez-Ceballos, G.; Goncharov, M.; González, O.; Gorelov, I.;
Goshaw, A. T.; Goulianos, K.; Grinstein, S.; Grosso-Pilcher, C.; Group,
R. C.; Guimaraes da Costa, J.; Hahn, S. R.; Halkiadakis, E.; Hamaguchi,
A.; Han, J. Y.; Happacher, F.; Hara, K.; Hare, D.; Hare, M.; Harnik,
R.; Harr, R. F.; Hatakeyama, K.; Hays, C.; Heck, M.; Heinrich, J.;
Herndon, M.; Hewamanage, S.; Hocker, A.; Hopkins, W.; Horn, D.; Hou,
S.; Hughes, R. E.; Hurwitz, M.; Husemann, U.; Hussain, N.; Hussein, M.;
Huston, J.; Introzzi, G.; Iori, M.; Ivanov, A.; James, E.; Jang, D.;
Jayatilaka, B.; Jeon, E. J.; Jindariani, S.; Jones, M.; Joo, K. K.;
Jun, S. Y.; Junk, T. R.; Kamon, T.; Karchin, P. E.; Kasmi, A.; Kato,
Y.; Ketchum, W.; Keung, J.; Khotilovich, V.; Kilminster, B.; Kim,
D. H.; Kim, H. S.; Kim, J. E.; Kim, M. J.; Kim, S. B.; Kim, S. H.;
Kim, Y. K.; Kim, Y. J.; Kimura, N.; Kirby, M.; Klimenko, S.; Knoepfel,
K.; Kondo, K.; Kong, D. J.; Konigsberg, J.; Kotwal, A. V.; Kreps,
M.; Kroll, J.; Krop, D.; Kruse, M.; Krutelyov, V.; Kuhr, T.; Kurata,
M.; Kwang, S.; Laasanen, A. T.; Lami, S.; Lammel, S.; Lancaster, M.;
Lander, R. L.; Lannon, K.; Lath, A.; Latino, G.; LeCompte, T.; Lee,
E.; Lee, H. S.; Lee, J. S.; Lee, S. W.; Leo, S.; Leone, S.; Lewis,
J. D.; Limosani, A.; Lin, C. -J.; Lindgren, M.; Lipeles, E.; Lister,
A.; Litvintsev, D. O.; Liu, C.; Liu, H.; Liu, Q.; Liu, T.; Lockwitz,
S.; Loginov, A.; Lucchesi, D.; Lueck, J.; Lujan, P.; Lukens, P.; Lungu,
G.; Lys, J.; Lysak, R.; Madrak, R.; Maeshima, K.; Maestro, P.; Malik,
S.; Manca, G.; Manousakis-Katsikakis, A.; Margaroli, F.; Marino, C.;
Martínez, M.; Mastrandrea, P.; Matera, K.; Mattson, M. E.; Mazzacane,
A.; Mazzanti, P.; McFarland, K. S.; McIntyre, P.; McNulty, R.; Mehta,
A.; Mehtala, P.; Mesropian, C.; Miao, T.; Mietlicki, D.; Mitra, A.;
Miyake, H.; Moed, S.; Moggi, N.; Mondragon, M. N.; Moon, C. S.; Moore,
R.; Morello, M. J.; Morlock, J.; Movilla Fernandez, P.; Mukherjee,
A.; Muller, Th.; Murat, P.; Mussini, M.; Nachtman, J.; Nagai, Y.;
Naganoma, J.; Nakano, I.; Napier, A.; Nett, J.; Neu, C.; Neubauer,
M. S.; Nielsen, J.; Nodulman, L.; Noh, S. Y.; Norniella, O.; Oakes, L.;
Oh, S. H.; Oh, Y. D.; Oksuzian, I.; Okusawa, T.; Orava, R.; Ortolan,
L.; Pagan Griso, S.; Pagliarone, C.; Palencia, E.; Papadimitriou,
V.; Paramonov, A. A.; Patrick, J.; Pauletta, G.; Paus, C.; Pellett,
D. E.; Penzo, A.; Phillips, T. J.; Piacentino, G.; Pianori, E.; Pilot,
J.; Pitts, K.; Plager, C.; Pondrom, L.; Poprocki, S.; Potamianos,
K.; Prokoshin, F.; Pranko, A.; Ptohos, F.; Punzi, G.; Rahaman, A.;
Ramakrishnan, V.; Ranjan, N.; Redondo, I.; Renton, P.; Rescigno,
M.; Riddick, T.; Rimondi, F.; Ristori, L.; Robson, A.; Rodrigo, T.;
Rodriguez, T.; Rogers, E.; Rolli, S.; Roser, R.; Ruffini, F.; Ruiz,
A.; Russ, J.; Rusu, V.; Safonov, A.; Sakumoto, W. K.; Sakurai, Y.;
Santi, L.; Sato, K.; Saveliev, V.; Savoy-Navarro, A.; Schlabach, P.;
Schmidt, A.; Schmidt, E. E.; Schwarz, T.; Scodellaro, L.; Scribano, A.;
Scuri, F.; Seidel, S.; Seiya, Y.; Semenov, A.; Sforza, F.; Shalhout,
S. Z.; Shears, T.; Shepard, P. F.; Shimojima, M.; Shochet, M.;
Shreyber-Tecker, I.; Simonenko, A.; Sinervo, P.; Sliwa, K.; Smith,
J. R.; Snider, F. D.; Soha, A.; Sorin, V.; Song, H.; Squillacioti,
P.; Stancari, M.; St. Denis, R.; Stelzer, B.; Stelzer-Chilton, O.;
Stentz, D.; Strologas, J.; Strycker, G. L.; Sudo, Y.; Sukhanov, A.;
Suslov, I.; Takemasa, K.; Takeuchi, Y.; Tang, J.; Tecchio, M.; Teng,
P. K.; Thom, J.; Thome, J.; Thompson, G. A.; Thomson, E.; Toback,
D.; Tokar, S.; Tollefson, K.; Tomura, T.; Tonelli, D.; Torre, S.;
Torretta, D.; Totaro, P.; Trovato, M.; Ukegawa, F.; Uozumi, S.;
Varganov, A.; Vázquez, F.; Velev, G.; Vellidis, C.; Vidal, M.; Vila,
I.; Vilar, R.; Vizán, J.; Vogel, M.; Volpi, G.; Wagner, P.; Wagner,
R. L.; Wakisaka, T.; Wallny, R.; Wang, S. M.; Warburton, A.; Waters,
D.; Wester, W. C., III; Whiteson, D.; Wicklund, A. B.; Wicklund, E.;
Wilbur, S.; Wick, F.; Williams, H. H.; Wilson, J. S.; Wilson, P.;
Winer, B. L.; Wittich, P.; Wolbers, S.; Wolfe, H.; Wright, T.; Wu,
X.; Wu, Z.; Yamamoto, K.; Yamato, D.; Yang, T.; Yang, U. K.; Yang,
Y. C.; Yao, W. -M.; Yeh, G. P.; Yi, K.; Yoh, J.; Yorita, K.; Yoshida,
T.; Yu, G. B.; Yu, I.; Yu, S. S.; Yun, J. C.; Zanetti, A.; Zeng, Y.;
Zhou, C.; Zucchelli, S.
Bibcode: 2012PhRvL.108u1804A
Altcode: 2012arXiv1203.0742T
We present the results of a search for dark matter production
in the monojet signature. We analyze a sample of Tevatron pp¯
collisions at s=1.96TeV corresponding to an integrated luminosity of
6.7fb-1 recorded by the CDF II detector. In events with large
missing transverse energy and one energetic jet, we find good agreement
between the standard model prediction and the observed data. We set 90%
confidence level upper limits on the dark matter production rate. The
limits are translated into bounds on nucleon-dark matter scattering
rates which are competitive with current direct detection bounds on
spin-independent interaction below a dark matter candidate mass of
5GeV/c2, and on spin-dependent interactions up to masses
of 200GeV/c2.
Title: HELIO: The Heliophysics Integrated Observatory
Authors: Bentley, R. D.; Csillaghy, A.; Aboudarham, J.; Jacquey, C.;
Hapgood, M. A.; Bocchialini, K.; Messerotti, M.; Brooke, J.; Gallagher,
P.; Fox, P.; Hurlburt, N.; Roberts, D. A.; Duarte, L. Sanchez
Bibcode: 2011AdSpR..47.2235B
Altcode:
Heliophysics is a new research field that explores the Sun-Solar System
Connection; it requires the joint exploitation of solar, heliospheric,
magnetospheric and ionospheric observations.HELIO, the Heliophysics
Integrated Observatory, will facilitate this study by creating an
integrated e-Infrastructure that has no equivalent anywhere else. It
will be a key component of a worldwide effort to integrate heliophysics
data and will coordinate closely with international organizations to
exploit synergies with complementary domains.HELIO was proposed under a
Research Infrastructure call in the Capacities Programme of the European
Commission’s 7th Framework Programme (FP7). The project was selected
for negotiation in January 2009; following a successful conclusion to
these, the project started on 1 June 2009 and will last for 36 months.
Title: VOs and Heliophysics: Would anyone like some CASSIS?
Authors: Bentley, R. D.; Lapenta, G.; Blanc, M.; Fox, P.; Walker,
R. J.; Cassis Team
Bibcode: 2010AGUFMIN23B1358B
Altcode:
Virtual Observatories related to heliophysics have emerged in various
regions of the World. Partly because of their sources of funding the
emphasis they place on aspects of the problem differ and how well
they can be integrated with other capabilities varies to a greater or
lesser degree. We examine virtual observatories that are available in
heliophysics and related disciplines and compare their capabilities and
look at where their strengths lie. We also identify some of the steps
that are needed to improve interoperability between the VO initiatives
and propose that discussions under the auspices of CASSIS could
help us globally to move towards this overall objective. CASSIS, the
Coordination Action for the integration of Solar System Infrastructure
and Science, is funded under Capacities specific programme of the
European Commission' Seventh Framework Programme (FP7) and has the
objective of exploring ways to improve interoperability for all aspects
of Solar System Science. CASSIS grew out of the HELIO, Europlanet RI
and SOTERIA projects and also includes other key partners, including
NASA, ESA, and NOAA. We welcome participation by other interested
organisations.
Title: HELIO as a Space Weather tool
Authors: Bentley, Robert; Hapgood, Mike; Messerotti, Mauro; Aboudarham,
Jean; Jacquey, Christian; Fox, Peter
Bibcode: 2010cosp...38.4171B
Altcode: 2010cosp.meet.4171B
The Heliophysics Integrated Observatory, HELIO, is primarily designed
to support research into the connection between solar phenomena,
interplanetary disturbances and their effects on the planets. However,
many of the techniques that are being developed and standards that we
are proposing have direct relevance to the more immediate requirements
of the space weather community. HELIO is being developed around
a service-oriented architecture and the services that can be used
either independently or as part of a work flow. The HELIO event and
feature catalogues, context service and metadata evaluation service may
all be of use to the community as capa-bilities in their own right;
they could also be combined in workflows that are specific to the
needs of research into space-weather. We have been examining ways of
enhancing the quality of the output produced by the services by adding
annotation that is compliant with standards proposed by the IVOA,
IPDA and IAU; if adopted across the space weather community these
additions could improve the interoperability of our data products
with related communities. Of necessity HELIO has to address data
providers in a number of different and well estab-lished communities,
each with its own way of describing and handling the data; in addition,
the capabilities of the providers and means of access to the data also
vary considerably. We have therefore had to develop techniques to handle
this, including archives where interesting observations may be available
but not easily accessible. HELIO is a research infrastructure funded
under Capacities programme of the EC's 7th Frame-work Programme (FP7);
the project started in June 2009 and has a duration of 36 months. The
HELIO Consortium includes thirteen groups from the UK, France, Ireland,
Italy, Switzerland, Spain and the US.
Title: Unique Science Needs: CAWSES-II and Virtual Observatories
(Invited)
Authors: Kozyra, J. U.; Fox, P. A.; Avery, S. K.; Rodger, A. S.;
Melkers, J. E.; Paxton, L. J.; Barnes, R. J.
Bibcode: 2009AGUFMSH54A..03K
Altcode:
A focus on the interaction between Sun-Earth system elements in space
research is not new. However, two recent events have pushed us within
reach of a comprehensive attack on system-science frontiers. During the
last solar cycle, we acquired the capability to observe simultaneously
in regions from the Sun to the Earth, in the neighborhoods of other
solar system planets and even at locations approaching the boundary
between the heliosphere and interplanetary space. Simultaneity is
critical because only under these conditions can interactions between
components be observed and unraveled. Of equal importance is the
implementation (still ongoing) of open data policies in the US and in
other countries that has resulted in a worldwide flow of data served
through the Internet directly and by Virtual Observatories. These open
data sets and underlying cyber-infrastructure provide the framework
around which a system science observatory can be fashioned and directed
toward grand challenge investigations. This effort must be both
interdisciplinary and international in scope. The development of just
such a virtual environment is a major goal of the Climate and Weather of
the Sun-Earth System (CAWSES) - II effort (covering 2009-2013) within
SCOSTEP, which is a program of the International Council for Science
(ICSU) representing 113 member nations and 29 international scientific
unions. With the collaboration of ongoing programs in countries around
the world, this virtual environment is envisioned as a means to combine
worldwide capabilities inherent in virtual observatories and other
types of cyber-infrastructure in ways that support and enable system
science investigations, allow international and interdisciplinary
communities to develop focused system-level science objectives,
exchange information intuitively between discipline areas, share
resources, educate students, advise policy makers, and reach out
and inform a worldwide public of exciting new discoveries and their
implications. This presentation focuses on the developing vision for
virtual observatories as a major part of the infrastructure underlying
a dynamic CAWSES-II virtual Sun-Earth system-science environment.
Title: Solar Surface Magnetism and Irradiance on Time Scales from
Days to the 11-Year Cycle
Authors: Domingo, V.; Ermolli, I.; Fox, P.; Fröhlich, C.; Haberreiter,
M.; Krivova, N.; Kopp, G.; Schmutz, W.; Solanki, S. K.; Spruit, H. C.;
Unruh, Y.; Vögler, A.
Bibcode: 2009SSRv..145..337D
Altcode:
The uninterrupted measurement of the total solar irradiance during the
last three solar cycles and an increasing amount of solar spectral
irradiance measurements as well as solar imaging observations
(magnetograms and photometric data) have stimulated the development
of models attributing irradiance variations to solar surface
magnetism. Here we review the current status of solar irradiance
measurements and modelling efforts based on solar photospheric
magnetic fields. Thereby we restrict ourselves to the study of solar
variations from days to the solar cycle. Phenomenological models
of the solar atmosphere in combination with imaging observations of
solar electromagnetic radiation and measurements of the photospheric
magnetic field have reached high enough quality to show that a large
fraction (at least, about 80%) of the solar irradiance variability
can be explained by the radiative effects of the magnetic activity
present in the photosphere. Also, significant progress has been made
with magnetohydrodynamic simulations of convection that allow us to
relate the radiance of the photospheric magnetic structures to the
observations.
Title: Ontology-supported scientific data frameworks: The Virtual
Solar-Terrestrial Observatory experience
Authors: Fox, Peter; McGuinness, Deborah L.; Cinquini, Luca; West,
Patrick; Garcia, Jose; Benedict, James L.; Middleton, Don
Bibcode: 2009CG.....35..724F
Altcode:
We have developed a semantic data framework that supports
interdisciplinary virtual observatory projects across the fields of
solar physics, space physics and solar-terrestrial physics. This work
required a formal, machine understandable representation for concepts,
relations and attributes of physical quantities in the domains of
interest as well as their underlying data representations. To fulfill
this need, we developed a set of solar-terrestrial ontologies as formal
encodings of the knowledge in the Ontology Web Language-Description
Logic (OWL-DL) format. We present our knowledge representation and
reasoning needs motivated by the context of Virtual Observatories, from
fields spanning upper atmospheric terrestrial physics to solar physics,
whose intent is to provide access to observational datasets. The
resulting data framework is built upon semantic web methodologies
and technologies and provides virtual access to distributed and
heterogeneous sets of data as if all resources appear to be organized,
stored and retrieved from a local environment. Our conclusion is
that the combination of use case-driven, small and modular ontology
development, coupled with free and open-source software tools and
languages provides sufficient expressiveness and capabilities for
an initial production implementation and sets the stage for a more
complete semantic-enablement of future frameworks.
Title: The Revolution in Astronomy Education: Data Science for
the Masses
Authors: Borne, Kirk D.; Jacoby, Suzanne; Carney, Karen; Connolly,
Andy; Eastman, Timothy; Raddick, M. Jordan; Wallin, John; Becla,
Jacek; Castelez, Michael; Connors, Allana; Hamilton, Tim; Lintott,
Chris; McCollum, Bruce; Fox, Peter; Mahabal, Ashish; Olsen, Julia;
Pesenson, Misha; Ptak, Andrew; Ross, Nic; Schweitzer, Andrea; Teays,
Terry; Way, Michael; Wood-Vasey, Michael
Bibcode: 2009astro2010P...7B
Altcode: 2009arXiv0909.3895B
As our capacity to study ever-expanding domains of our science has
increased (including the time domain, non-electromagnetic phenomena,
magnetized plasmas, and numerous sky surveys in multiple wavebands with
broad spatial coverage and unprecedented depths), so have the horizons
of our understanding of the Universe been similarly expanding. This
expansion is coupled to the exponential data deluge from multiple
sky surveys, which have grown from gigabytes into terabytes during
the past decade, and will grow from terabytes into Petabytes (even
hundreds of Petabytes) in the next decade. With this increased
vastness of information, there is a growing gap between our awareness
of that information and our understanding of it. Training the next
generation in the fine art of deriving intelligent understanding from
data is needed for the success of sciences, communities, projects,
agencies, businesses, and economies. This is true for both specialists
(scientists) and non-specialists (everyone else: the public, educators
and students, workforce). Specialists must learn and apply new data
science research techniques in order to advance our understanding of
the Universe. Non-specialists require information literacy skills
as productive members of the 21st century workforce, integrating
foundational skills for lifelong learning in a world increasingly
dominated by data. We address the impact of the emerging discipline
of data science on astronomy education within two contexts: formal
education and lifelong learners.
Title: Enabling Science Research with Coordinated Data From SuperDARN
and VITMO
Authors: Barnes, R. J.; Morrison, D.; Weiss, M.; Immer, E.; Potter,
M.; Holder, R.; Patrone, D.; Colclough, C.; McGuire, R.; Candey, R.;
Bilitza, D.; Harris, B.; Kozyra, J.; Fox, P.; Heelis, R.; Russell, J.
Bibcode: 2008AGUFMSA53A1578B
Altcode:
One of the important capabilities introduced with Virtual Observatories
is the ability to seamlessly obtain data from multiple sites/instruments
at simultaneous times. This facilitates coordinated research,
particularly involving ground and satellite based data sets. In this
presentation we will show how the ground based SuperDARN network data
have been integrated into the Virtual ITM Observatory (VITMO). These
data can be used with coordinated observations from satellites
(e.g. TIMED). In this presentation we will show how coordinated data
sets can be selected through the VITMO interface and all products
downloaded to the user in a single zip file, greatly facilitating
coordinated research. We will show how new elements from SuperDARN
have been brought over into the VITMO interface allowing for the full
fidelity provided by SuperDARN to be available for data selection
through VITMO as well. We will also demonstrate possible future data
products that can be generated using VITMO to combine multiple data
sets.
Title: Performing Science Research with the Virtual ITM Observatory
Authors: Morrison, D.; Weiss, M.; Immer, L.; Patrone, D.; Potter, M.;
Holder, R.; Barnes, R.; Colclough, C.; Nylund, S.; Yee, J.; Talaat,
E.; Bilitza, D.; McGuire, R.; Candey, R.; Harris, B.; Russell, J.;
Heelis, R.; Kozyra, J.; Fox, P.
Bibcode: 2008AGUFMSA53A1575M
Altcode:
The Virtual ITM Observatory (VITMO) is a system that integrates
data providers and other virtual observatories together to give the
appearance of a seamless system. This seamless appearance allows the
user to create a virtual observing system dedicated to the individual's
research interests. VITMO has reached operational status with additional
capabilities and datasets being rolled out over time. The design of
the Virtual ITM Observatory (VITMO) was developed out of a series of
use cases for ITM science data analysis. To enhance the capability of
the scientist in studying the ITM region and its response to energetic
inputs as a system, the need existed for an ability to approach problems
using coordinated observations. This provided the basis for developing
tools to identify coordinated observations, geophysics condition based
searches, and an ability to provide these capabilities across multiple
data sets. This talk will focus on examples of how these capabilities
allow the scientist to perform "what-if" based searches of data for
analysis along with a discussion of the types of scientific analysis
that may be possible through this system.
Title: Next Generation Virtual Observatories
Authors: Fox, P.; McGuinness, D. L.
Bibcode: 2008AGUFMIN22A..01F
Altcode:
Virtual Observatories (VO) are now being established in a variety
of geoscience disciplines beyond their origins in Astronomy and Solar
Physics. Implementations range from hydrology and environmental sciences
to solid earth sciences. Among the goals of VOs are to provide search/
query, access and use of distributed, heterogeneous data resources. With
many of these goals being met and usage increasing, new demands and
requirements are arising. In particular there are two of immediate
and pressing interest. The first is use of VOs by non-specialists,
especially for information products that go beyond the usual data, or
data products that are sought for scientific research. The second area
is citation and attribution of artifacts that are being generated by
VOs. In some sense VOs are re-publishing (re-packaging, or generating
new synthetic) data and information products. At present only a few VOs
address this need and it is clear that a comprehensive solution that
includes publishers is required. Our work in VOs and related semantic
data framework and integration areas has lead to a view of the next
generation of virtual observatories which the two above-mentioned needs
as well as others that are emerging. Both of the needs highlight a
semantic gap, i.e. that the meaning and use for a user or users beyond
the original design intention is very often difficult or impossible
to bridge. For example, VOs created for experts with complex, arcane
or jargon vocabularies are not accessible to the non-specialist and
further, information products the non-specialist may use are not created
or considered for creation. In the second case, use of a (possibly
virtual) data or information product (e.g. an image or map) as an
intellectual artifact that can be accessed as part of the scientific
publication and review procedure also introduces terminology gaps, as
well as services that VOs may need to provide. Our supposition is that
formalized methods in semantics and semantic web technologies are ideal
to meet and solve both of these semantic gaps. In this presentation
we highlight both of the emerging needs, and current and emerging
semantic web solutions that will enable the next generation of virtual
observatories. Our work is funded under NSF/OCI and NASA/ACCESS/ESTO
projects to the High Altitude Observatory at the National Center for
Atmospheric Research (NCAR) and McGuinness Associates Consulting.
Title: Reactive transport modeling of U(VI) in small-scale tracer
tests
Authors: Curtis, G. P.; Kohler, M.; Davis, J. A.; Fox, P. M.
Bibcode: 2008GeCAS..72R.192C
Altcode:
No abstract at ADS
Title: Provenance in Observational Solar Physics Data Pipelines
Authors: McGuinness, D.; Fox, P.; Garcia, J.; Zednik, S.
Bibcode: 2008AGUSMIN44A..02M
Altcode:
A limiting factor for virtual observatories which intend to make diverse
data sets available to a diverse user base is that the following
use cases are very difficult to implement: 1. Determine which flat
field calibration was applied to the image taken on January, 26,
2005 around 2100UT by the ACOS Mark IV polarimeter. 2. What processing
steps were completed to obtain the ACOS PICS limb image of the day for
January 26, 2005. 3. What was the cloud cover and atmospheric seeing
conditions during the local morning of January 26, 2005 at MLSO. Key to
addressing these use cases often requires information that was either
not collected from different stages in the data processing pipeline or
it was but was not carried forward when the datasets were made available
on-line. Collectively, this information is called provenance and in a
semantic web data framework; knowledge provenance. In this presentation,
we describe the knowledge provenance requirements that have emerged
in our previous work on virtual observatories as well as requirements
identified from a series of uses cases collected from scientific data
users and instrument scientists. We will describe the progress we are
making on meeting these requirements in the context of solar physics
image data processing pipelines. The Semantic Provenance Capture
in Data Ingest Systems (SPCDIS) is a NSF OCI/SDCI-funded project to
implement an extensible meta data provenance scheme within the Virtual
Solar-Terrestrial Observatory.
Title: Enabling Visual Search and Discovery with the Virtual ITM
Observatory
Authors: Morrison, D.; Immer, L.; Daley, R.; Patrone, D.; Potter, M.;
Holder, R.; Barnes, R.; Colclough, C.; Nylund, S.; Yee, J.; Talaat,
E.; Russell, J.; Heelis, R.; Kozyra, J.; Bilitza, D.; McGuire, R.;
Candey, R.; Fox, P.
Bibcode: 2008AGUSMSM21A..03M
Altcode:
The Virtual ITM Observatory (VITMO) is one of the recently selected NASA
domain specific virtual observatories designed to facilitate study of
the ionosphere, thermosphere, and mesosphere (ITM) regions. VITMO sits
above mission datacenters and provide outside users with the ability to
find data sets across multiple datacenters and more importantly, find
those datasets that overlap in time and/or space allowing coordinated
observations of phenomena. VITMO provides many methods by which the
user can search for and select data of interest including restricting
selections based on geophysical conditions (solar wind speed, Kp,
etc). A recent addition to VITMO is the support for "summary images"
that many instrument teams use to allow the user to identify data
sets of interest. VITMO has expanded this capability by automatically
tying together summary images and the data sets they are derived
from. This facility allows the user to "thumb through" the summary
images, indicating those of interest, automatically selecting all of
the appropriate data products for download. This gives the user an
ability to select based on "identified features" that the user finds
in the visual representations of the data sets.
Title: Enabling New Discovery with the Virtual ITM Observatory
Authors: Morrison, D.; Immer, L.; Dailey, R.; Patrone, D.; Potter, M.;
Holder, R.; Barnes, R.; Colclough, C.; Nylund, S.; Yee, J.; Talaat,
E.; Russell, J.; Heelis, R.; Kozyra, J.; Bilitza, D.; McGuire, R.;
Candey, R.; Fox, P.
Bibcode: 2008AGUSMSM31A..01M
Altcode:
While a Virtual Observatory can be thought of as a software system
that provides uniform access to multiple data sets, it can also be
considered a system that allows the user to create a virtual observing
system dedicated to the individual's research interests. This latter
approach was the goal of the Virtual ITM Observatory (VITMO) which
has now reached operational status. The design of the Virtual ITM
Observatory (VITMO) was developed out of a series of use cases for
ITM science data analysis. To enhance the capability of the scientist
in studying the ITM region and its response to energetic inputs as a
system, the need was shown for an ability to approach problems using
coordinated observations. This systems approach required the Virtual
ITM Observatory to allow the user to locate data files that overlap
in time and space, creating a virtual satellite to make coordinated
observations of phenomena. VITMO provides tools to take the drudgery
out of locating simultaneous overlapping datasets from multiple
satellites and satellite-ground site conjunctions. Many of these
tools are integrated into the search system allowing the user to find
files automatically when certain geophysical conditions are present,
a satellite observes a region at the same time a ground based radar
system is operating, or other conditions are met. A recent addition to
VITMO is the support for "summary images" that many instrument teams
use to allow the user to identify data sets of interest. VITMO has
expanded this capability by automatically tying together summary images
and the data sets they are derived from. This facility allows the user
to "thumb through" the summary images, indicating those of interest,
automatically selecting all of the appropriate data products for
download. This gives the user an ability to select based on "identified
features" that the user finds in the visual representations of the data
sets. Examples of how these capabilities allow the scientist to perform
"what-if" based searches of data for analysis will be presented in a
demo along with a discussion of the types of scientific analysis that
may be possible through this system.
Title: Handling knowledge via Concept Maps: a space weather use case
Authors: Messerotti, Mauro; Fox, Peter
Bibcode: 2008cosp...37.2019M
Altcode: 2008cosp.meet.2019M
Concept Maps (Cmaps) are powerful means for knowledge coding in
graphical form. As flexible software tools exist to manipulate the
knowledge embedded in Cmaps in machine-readable form, such complex
entities are suitable candidates not only for the representation of
ontologies and semantics in Virtual Observatory (VO) architectures,
but also for knowledge handling and knowledge discovery. In this work,
we present a use case relevant to space weather applications and we
elaborate on its possible implementation and adavanced use in Semantic
Virtual Observatories dedicated to Sun-Earth Connections. This analysis
was carried out in the framework of the Electronic Geophysical Year
(eGY) and represents an achievement synergized by the eGY Virtual
Observatories Working Group.
Title: The World Informatics Scene: ICSU, International Unions and
Associations, Professional Society Activities
Authors: Fox, Peter
Bibcode: 2008cosp...37..924F
Altcode: 2008cosp.meet..924F
In the lead up to, and during, the Electronic Geophysical Year
(2007-2008), a substantial number of new coordinated efforts under
the heading of informatics (defined as: ) have emerged. These efforts
range from the formation of divisions/ sections in societies such as the
Geological Society of America, the American Geophysical Union and the
European Geosciences Union devoted to all aspects of informatics and
have seen strong community response at their regular meetings. These
society efforts are closer to the working scientists, technologists
and data producers, and managers. At the same time, in a recognition
for the need of a sustained activity such as eGY, two ad-hoc committees
produced proposals for a) the formation of a Union Commission for Data
and Information within the International Union of Geodesy and Geophysics
(IUGG) and b) the Committee on Data for Science and Technology (CODATA)
approved a Working Group on XX, with the intent that it will become a
Task Group after the 2008 CODATA general assembly. The International
Council of Science's (ICSU) Strategic Committee on Information and
Data (SCID) will deliver its report on implementation ICSU's priority
area assessment strategy for ICSU to play a leadership role in the
coordination of data and information efforts world-wide. This report
will influence entities such as CODATA, the World Data Centres, the
Federation of Astrophysical and Geophysical Data Services (FAGS) and,
most likely, all ICSU Unions. This presentation will give details on
the abovementioned activities and indicate an emerging synergy for
Informatics across many discipline and the advancement of science and
societal goals. The presentation will also include suggestions for
the COSPAR community to engage in on-going activities.
Title: Virtual Observatories in Earth and Space Science
Authors: Fox, Peter
Bibcode: 2008cosp...37..925F
Altcode: 2008cosp.meet..925F
This presentation will define the virtual observatory (VO), explain
its general concepts and the paradigm it has introduced. We then survey
some existing and planned virtual observatories, describe their goals,
design, current implementations and technical infrastructure. We
present what has been learned about building such VOs and what the
future holds for the general paradigm and what potential technical
challenges need to be addressed concerning (at least) representations
and interoperability of data, access, and usability across the wide
variety of disciplines in geosciences.
Title: The Rosetta Model: Can the Different Physical Science Data
Models be Reconciled?
Authors: King, T. A.; McGuinness, D. L.; Walker, R. J.; Fox, P.;
Roberts, D. A.; Harvey, C.
Bibcode: 2007AGUFMIN53B1209K
Altcode:
There are a variety of data models in the physical sciences, some of
which are in overlapping domains. Each of the data models have been
derived in different ways. Some have been based on formal ontologies,
others on informal ontologies and others on relational schemas. An
additional complication is that different international agencies have
divided the physical science domains into different sub-domains leading
to some confusion as to which data model to adopt. The most prevalent
data models in use today are the Planetary Data System (PDS), Space
Physics Archive Search and Extract (SPASE), Virtual Solar Terrestrial
Observatory (VSTO), the International Virtual Observatory Alliance
(IVOA) and the Global Change Master Directory (GCMD). We take a
comparative look at the various data models and ask the questions:
Can they be reconciled? Is it possible to have a Rosetta Model to
translate between each of the models? What role can ontologies play
in defining a Rosetta Model?
Title: Current and future uses of OWL for Earth and Space science
data frameworks: successes and limitations
Authors: West, P.; McGuinness, D.; Fox, P.; Cinquini, L.
Bibcode: 2007AGUFMIN53B1207W
Altcode:
Based on almost three years of experience in developing and deploying
scientific data frameworks built using semantic technologies, we
now have a production virtual observatory in operation, serving two
broad communities: solar physics and terrestrial upper atmospheric
physics. Within this application, a data framework provides online
location, retrieval, and analysis services to a variety of heterogeneous
scientific data sources distributed over the internet. We describe
selected current and planned uses of our ontologies in OWL-DL, and tools
involved in development and deployment. We describe both successes
and limitations we have found to date using OWL- based technologies,
especially tool support. We also indicate the important components we
require from a robust technical infrastructure as we move forward with
expanding the functionality of the frameworks. This expansion includes
additional semantic representation and reasoning/query services as
well as broadening the scope of our scientific disciplines.
Title: Enabling Science with the Virtual ITM Observatory
Authors: Morrison, D.; Weiss, M.; Immer, L.; Holder, R.; Barnes,
R.; Colclough, C.; Potter, M.; Daley, R.; Hashemian, M.; Nylund, S.;
Yee, S.; Talaat, E.; Russell, J.; Heelis, R.; Kozyra, J.; Bilitza,
D.; McGuire, R.; Candey, R.; Fox, P.
Bibcode: 2007AGUFMSH54C..02M
Altcode:
While a Virtual Observatory can be thought of as a software system
that provides uniform access to multiple data sets, it can also be
considered a system that allows the user to create a virtual observing
system dedicated to the individual's research interests. This latter
approach is the goal of the Virtual ITM Observatory (VITMO) which
has now reached operational status. The design of the Virtual ITM
Observatory (VITMO) was developed out of a series of use cases for
ITM science data analysis. To enhance the capability of the scientist
in studying the ITM region and its response to energetic inputs as a
system, the need was shown for an ability to approach problems using
coordinated observations. This systems approach required the Virtual
ITM Observatory to allow the user to locate data files that overlap
in time and space, creating a virtual satellite to make coordinated
observations of phenomena. VITMO provides tools to take the drudgery
out of locating simultaneous overlapping datasets from multiple
satellites and satellite-ground site conjunctions. Many of these
tools are integrated into the search system allowing the user to find
files automatically when certain geophysical conditions are present,
a satellite observes a region at the same time a ground based radar
system is operating, or other conditions are met. These and future
enhanced capabilities such as selecting data sets for study based
on model/data comparisons will be presented. Also included, will be
examples of how these capabilities allow the scientist to perform
"what-if" based searches of data for analysis and a discussion of
the types of scientific analysis that may be feasible through the
VITMO. VITMO can be found at http://vitmo.jhuapl.edu/.
Title: The Virtual Solar-Terrestrial Observatory: interdisciplinary
data-driven science
Authors: Fox, P. A.; McGuinness, D. L.; Middleton, D.; Cinuini, L.;
Garcia, J.; West, P.; Darnell, J. A.; Benedict, J.
Bibcode: 2007HiA....14..628F
Altcode: 2006IAUSS...3E..78F
Virtual Observatories can provide access to vast stores of
scientific data: observations and models. As these electronic stores
become widely used, there is potential to improve the efficiency,
interoperability, collaborative potential, and impact of a wide range
of interdisciplinary scientific research. In order to realize this
potential, technical challenges need to be addressed concerning
(at least) representations and interoperability of data, access,
and usability. In the Virtual Solar Terrestrial Observatory (VSTO)
project, we are providing an electronic repository of observational data
spanning the solar-terrestrial physics domain. We are also implementing
semantic web tools and infrastructure for accessing and using the
data. Our main contributions include the repository, infrastructure,
and tools for the particular solar terrestrial physics as well as
the design and infrastructure that may be broadened to cover more
diverse science areas and communities of use. In this presentation,
we describe the goals, design, current and planned prototypes, and
technical infrastructure. We present what we have learned about the
processes involved in developing VSTO and the required semantics,
how they affect the framework architecture, choice of technologies
and service interfaces. VSTO is an NSF-funded joint effort between
the High Altitude Observatory and the Scientific Computing Division
at the National Center for Atmospheric Research (NCAR) and McGuinness
Associates Consulting.
Title: VITMO: The Virtual Observatory for the ITM Community
Authors: Morrison, D.; Weiss, M.; Daley, R.; Immer, L.; Colclough, C.;
Holder, R.; Jen, J.; Hashemian, M.; Meckel, P.; Potter, M.; Barnes,
R.; Nylund, S.; Yee, J.; Talaat, E.; Russell, J.; Heelis, R.; Kozyra,
J.; Bilitza, D.; McGuire, R.; Candey, R.; Fox, P.
Bibcode: 2007AGUSMSM23A..03M
Altcode:
The Virtual ITM Observatory (VITMO) is one of the recently selected
NASA domain specific virtual observatories designed to facilitate study
of the ionosphere, thermosphere, and mesosphere (ITM) regions. The ITM
domain studies an area of the atmosphere that is a transition region
between the atmosphere and space, where many important physical and
chemical processes change dramatically temporally and spatially. As
a result, the areas of studies within the ITM community span a wide
spectrum of scientific subjects in geophysics and space physics. The
VITMO will sit above mission datacenters and provide outside users
with the ability to find data sets across multiple datacenters and
more importantly, find those datasets that overlap in time and/or space
allowing coordinated observations of phenomena. This will create a "true
virtual observatory" that utilizes many different instruments to study a
given system or phenomena. The design incorporates a modular framework
that accepts distributed data and services from across the community
and encourages widespread participation. The current and planned state
of the VITMO, which is to begin operation at the end of 2007, will be
presented along with a demonstration of some of its unique capabilities.
Title: The Virtual Solar-Terrestrial Observatory; access to and use
of diverse solar and solar-terrestrial data
Authors: Fox, P.
Bibcode: 2007AGUSMSM23A..02F
Altcode:
This presentation will demonstrate how users and other data providers
can utilize the Virtual Solar-Terrestrial Observatory (VSTO) to find,
access and use diverse data holdings from the disciplines of solar,
solar-terrestrial and space physics. VSTO provides a web portal, web
services and a native applications programming interface for various
levels of users. Since these access methods are based on semantic
web technologies and refer to the VSTO ontology, users also have the
option of taking advantage of value added services when accessing and
using the data. We present example of both conventional use of VSTO
as well as the advanced semantics use. Finally, we present our future
directions for VSTO and semantic data frameworks in general.
Title: VITMO: A Virtual Observatory for the ITM Community
Authors: Morrison, D.; Weiss, M.; Daley, R.; Immer, L.; Nylund, S.;
Yee, J.; Talaat, E.; Russell, J.; Heelis, R.; Kozyra, J.; Bilitza,
D.; McGuire, B.; Candey, R.; Fox, P.
Bibcode: 2006AGUFMSM21A0252M
Altcode:
The ionosphere, thermosphere, and mesosphere (ITM) is a transition
region between the atmosphere and space, where many important
physical and chemical processes change dramatically both temporally
and spatially. As a result, the areas of studies within the ITM
community span a wide spectrum of scientific subjects in geophysics
and space physics. The relevant data for the community collected
during the past few decades consequently come from a variety of
sources including ground and space-based instruments as well as
from modeling and data assimilation. This data has a number of
differences from data in other domains. The ITM region is observed
using a variety of techniques and data sources, including ground
based remote sensing instruments, satellite based remote sensing
instruments, and in-situ satellite instruments. In addition, there
are external drivers in solar radiation and the solar wind and
magnetospheric particle inputs. A Virtual Observatory that covers
the ITM region needs to deal with the large diversity of data types
and data formats in the study of this region. In this paper we will
present the design for the Virtual ITM Observatory (VITMO). The VITMO
will sit above mission datacenters and provide outside users with
the ability to find data sets across multiple datacenters and more
importantly, find those datasets that overlap in time and/or space
allowing coordinated observations of phenomena. This will create a
"true virtual observatory" that utilizes many different instruments to
study a given system or phenomena. The design incorporates a modular
framework that accepts distributed data and services from across the
community and encourages widespread participation. Data can be added
as both new missions and historical holdings become available, and
services added or replaced as technologies and standards evolve. The
core VITMO system is based upon a set of services: centralized browse
and query/retrieval of distributed resources, access to data reader
software and other tools, and integration of current data with data
from previous missions and long-term data sets. The VITMO will allow
vastly improved complex data search and location capabilities allowing
multidisciplinary and multisatellite studies to be performed. The
VITMO approach is easily extensible to future data sets and will be
able to tie into Virtual Observatories in other domains as either a
peer node or a service. The VITMO will also organize tools, whether
plotting, subsetting, or analysis tools by the type of data they
are to be applied to as well as the types of operations that are
to be performed. Relevant tools and models will be presented to the
user through a tabbed browser interface. This interface is generated
dynamically based on the metadata in the VITMO catalog that describes
the data, tools, and models available through it. The VITMO will
initially organize data from TIMED, AIM, C/NOFS, UARS, and SuperDARN
data sets as well as CDAWeb, SSCWeb, and ModelWeb web services.
Title: The Virtual Observatory as Critical Scientific Cyber
Infrastructure.
Authors: Fox, P.
Bibcode: 2006AGUFMSA43A..03F
Altcode:
Virtual Observatories can provide access to vast stores of scientific
data: observations and models as well as services to analyze, visualize
and assimilate multiple data sources. As these electronic resource
become widely used, there is potential to improve the efficiency,
interoperability, collaborative potential, and impact of a wide range
of interdisciplinary scientific research. In addition, we know that
as the diversity of collaborative science and volume of accompanying
data and data generators/consumers grows so do the challenges. In
order for Virtual Observatories to realize their potential and become
indispensible infrastructure, social, political and technical challenges
need to be addressed concerning (at least) roles and responsibilities,
data and services policies, representations and interoperability of
services, data search, access, and usability. In this presentation, we
discuss several concepts and instances of the Virtual Observatory and
related projects that may, and may not, be meeting the abovementioned
challanges. We also argue that science driven needs and architecture
development are critical in the development of sustainable (and
thus agile) cyberinfrastructure. Finally we some present or emerging
candidate technologies and organizational constructs that will need
to be pursued.
Title: Education and Public Outreach for eGY: Virtual Observatories
that connect teachers with authentic science data
Authors: Cobabe-Ammann, E.; Fox, P. A.
Bibcode: 2006IAUSS...2E.101C
Altcode:
The development of the virtual observatories for the eGY offers an
unprecedented educational opportunity to connect teachers throughout the
world to authentic data, both real-time and archived, in a standards-
and inquiry-based context. The goal of the eGY Education and Outreach is
to create an education portal that connects teachers, in a well-defined
way, to the virtual observatories. The programming developed would allow
teachers to use the virtual observatories and its data in an educational
context, with supporting materials and activities. In addition, and
perhaps as important, the portal would support virtual educational
communities, both synchronously and asynchronously. There would be
virtual seminars, not only on science content, but on the educational
technology and assessment, for example. We would provide multimedia
assets for teachers, including scientific talks, computer-based
animations and interactives. The educational portal would support the
interface to several virtual observatories from a wide variety of areas,
including for example, the carbon-cycle, the geospace environment,
and perhaps either the geological or oceanographic world, expanding
on the intellectual themes of all of the I*Ys and Planet Earth. We
partner with the other commemorative years, leveraging their network
of teachers worldwide and their educational programming while offering
them the portal as an opportunity for collaboration. While the active
programming might only exist for the eGY, the portal could be continued
indefinitely. 448
Title: Virtual Observatories in Earth and Space Sciences
Authors: Fox, P. A.
Bibcode: 2006IAUSS...6E..12F
Altcode:
This presentation will illustrate how the virtual observatory (VO)
concept has been implemented in a variety of earth and space science
discipline areas. We will describe their goals, design, current
implementations and technical infrastructure. We present what has
been learned about building such VOs and compare and contrast with
the astronomy VOs. We also outline what the future holds for the
general paradigm and what potential technical challenges need to be
addressed concerning (at least) representations and interoperability
of data, access, and usability across the wide variety of disciplines
in geosciences.
Title: A Virtual Observatory for the
Ionosphere-Mesosphere-Thermosphere Community
Authors: Morrison, D.; Weiss, M.; Daley, R.; Immer, E.; Nylund, S.;
Yee, J.; Talaat, E.; Russell, J.; Heelis, R.; Kozyra, J.; Bilitza,
D.; McGuire, R.; Candey, R.; Fox, P.
Bibcode: 2006AGUSMSM23A..06M
Altcode:
The ionosphere, thermosphere, and mesosphere (ITM) community studies
an area of the atmosphere that is a transition region between the
atmosphere and space, where many important physical and chemical
processes change dramatically temporally and spatially. As a result,
the areas of studies within the ITM community span a wide spectrum of
scientific subjects in geophysics and space physics. The relevant data
for the community collected during the past few decades consequently
come from a variety of sources including ground and space-based
instruments as well as from modeling and data assimilation. This
data has a number of differences from data in other domains. The ITM
region is observed using a variety of techniques and data sources,
including ground based remote sensing instruments, satellite based
remote sensing instruments, and in-situ satellite instruments. In
addition, there are external drivers in solar radiation and the
solar wind and magnetospheric particle inputs. A Virtual Observatory
that covers the ITM region needs to deal with the large diversity of
data types and data formats in the study of this region. We present a
Virtual ITM Observatory (VITMO) implementation for such a data system
that leverages current resources. The VITMO that is proposed here
will sit above mission datacenters and provide outside users with
the ability to find data sets across multiple datacenters and more
importantly, find those datasets that overlap in time and/or space
allowing coordinated observations of phenomena. This will create a
"true virtual observatory" that utilizes many different instruments to
study a given system or phenomena. The design incorporates a modular
framework that accepts distributed data and services from across the
community and encourages widespread participation. Data can be added
as both new missions and historical holdings become available, and
services added or replaced as technologies and standards evolve. The
core VITMO system is based upon a set of services: centralized browse
and query/retrieval of distributed resources, access to data reader
software and other tools, and integration of current data with data
from previous missions and long-term data sets. The VITMO will allow
vastly improved complex data search and location capabilities allowing
multidisciplinary and multisatellite studies to be performed. The
VITMO approach is easily extensible to future data sets and will be
able to tie into Virtual Observatories in other domains as either a
peer node or a service. The VITMO will also organize tools, whether
plotting, subsetting, or analysis tools by the type of data they
are to be applied to as well as the types of operations that are
to be performed. Relevant tools and models will be presented to the
user through a tabbed browser interface. This interface is generated
dynamically based on the metadata in the VITMO catalog that describes
the data, tools, and models available through it. The VITMO will
initially organize data from TIMED, AIM, C/NOFS, UARS, and SuperDARN
data sets as well as CDAWeb, SSCWeb, and ModelWeb web services.
Title: Open exchange of data: the eGY pathway towards capacity
building.
Authors: Barton, C.; Baker, D.; Cobabe-Ammann, E.; Fox, P.; Kihn,
E.; Peterson, W. K.
Bibcode: 2006cosp...36.2387B
Altcode: 2006cosp.meet.2387B
The Electronic Geophysical Year 2007-2008 eGY uses the 50-year
anniversary of the acclaimed International Geophysical Year to
advance open access to data information and services The International
Polar Years of 1882-1882 and 1932-1933 taught us that free and open
exchange of data between nations is cost effective The International
Geophysical Year 1957-1958 taught us that free and open exchange
of data between scientific disciplines generates new and exciting
research The worldwide network of data centers and data standards
initiated during IGY continues to foster research to this day And
better things lie ahead As we approach the 50th anniversary of the
IGY the development of distributed data systems allows worldwide
connectivity to data and services at a level never before possible
Such systems virtual observatories and so forth expand the free open
and cross-disciplinary exchange of data by allowing users worldwide
to access and manipulate data from principal data centers as well as
from small previously isolated research groups The new information and
communication technologies require that we adopt community-developed
standards for data storage and description They also demand that we
recognize and accommodate the shift in effort from the user to the
provider that accompanies a change from the traditional user-pull to a
modern provider-push data environment eGY provides an opportunity for
coordinated discussions on data storage and description standards These
standards have implications for the infrastructure needed to access and
Title: The Mauna Loa Solar Observatory as a Virtual Observatory
Data Provider
Authors: Darnell, T.; Burkepile, J.; Fox, P.
Bibcode: 2005AGUFMIN31B1154D
Altcode:
The High Altitude Observatory (HAO) has operated the Mauna Loa Solar
Observatory (MLSO) since 1965, recording low coronal white light and
Helium I and H-alpha disk images. Much of the data collected since
the opening of MLSO has been made available as an on-line image
archive, searchable using standard SQL queries. From its inception,
the current MLSO data archive was designed to interact with Virtual
Observatories (VO). It has since become a data provider of the Virtual
Solar Observatory (VSO), Virtual Solar Terrestrial Observatory (VSTO),
and work is underway to become a data provider for the European Grid of
Solar Observations (EGSO). Here we present a description of the MLSO
data archive and its datasets and outline our experience with working
with VO's from the perspective of a data provider. We also offer some
things to consider when providing data through a VO and illustrate
some of the issues we've encountered and practices we've adopted as a
VO data provider. Finally, we put forward some of our efforts designed
specifically for educators to access and utilize MLSO datasets.
Title: Data systems and data frameworks within the Virtual Observatory
concept.
Authors: Fox, P.
Bibcode: 2005AGUSMSH44A..01F
Altcode:
This presentation discusses the attributes of Virtual Observatories,
Grid technologies and data frameworks in general terms as they have
been applied to providing data to diverse and interdisciplinary
science communities. We discuss general user requirements, design and
architectural considerations, development and provision of services in
a web environment that arise out of past experience with data systems
over the last 8-10 years.
Title: The Virtual Solar-Terrestrial Observatory
Authors: Fox, P.; Middleton, D.; Solomon, S.; McGuinness, D.
Bibcode: 2005AGUSMSH42A..05F
Altcode:
The VSTO comprises a system of data, model, tool and material archives
containing items from space- and ground-based instruments, individual
and community modeling efforts, taken from NCAR, US universities and
international sources, and from NSF- and NASA-funded groups. A key
element of the VSTO is the allowance for an integrated data-mining
and analysis capability that can be applied both across and within
databases, i.e. across disciplines. The capabilities of a VSTO
are intended to be available to a wider community of scientists,
educators, and the public and thus is intended to be a natural conduit
for education and public outreach in solar solar-terrestrial and
space physics. This presentation will provide details on the current
stage of development of VSTO including use-cases, user requirements,
ontology development, project priorities, collaborations and current
design and implementations.
Title: Review of the current state of theoretical modeling of the
total solar irradiance
Authors: Fox, P.
Bibcode: 2005AGUSMSH22B..01F
Altcode:
We review the present state and latest results for theoretical models of
the total solar irradiance and certain important irradiance bands. We
highlight the ability, or lack thereof, of solar proxy data and
models to both represent the irradiance as well as its variability
on timescales ranging from days to multiple solar cycles. We also
contrast the theoretical models with other types of models that may
or may not have a physical basis for the form of the model. We also
comment on the degree of redundancy in parts of the solar spectrum and
how this could affect what wavelengths and bandpasses in the spectrum
are important for observing programs.
Title: Solar Variability and Earth's climate
Authors: Ermolli, Iliaria; Pap, Judit; Fox, Peter
Bibcode: 2005MmSAI..76..705E
Altcode:
No abstract at ADS
Title: The Virtual Solar-Terrestrial Observatory
Authors: Fox, P. A.; Middleton, D.; Solomon, S. C.; Garcia, J.;
Cinquini, L.; West, P.
Bibcode: 2004AGUFMSA54A..07F
Altcode:
The VSTO is being developed as a scalable environment for searching,
integrating, and analyzing databases distributed over the Internet. The
VSTO comprises a system of data, model, tool and material archives
containing items from space- and ground-based instruments, individual
and community modeling efforts, taken from NCAR, US universities and
international sources, and from NSF- and NASA-funded groups. A key
element of the VSTO is the allowance for an integrated data-mining
and analysis capability that can be applied both across and within
databases, i.e. across disciplines. The capabilities of a VSTO
are intended to be available to a wider community of scientists,
educators, and the public and thus is intended to be a natural conduit
for education and public outreach in solar solar-terrestrial and space
physics. This presentation will outline the key user requirements,
functionality, proposed architecture and technologies that will be used
in assembling the VSTO. We will also present past experience in building
elements of data and collaborations system and the lessons learned.
Title: Short-term changes in solar spectral irradiance - synthesis
calculations
Authors: White, O. R.; Fox, P. A.
Bibcode: 2004AGUFMSH53B0311W
Altcode:
We present the latest results from the SunRISE spectral synthesis in
specific spectral bands in the UV, visible, and near-IR in response
to short-term (days-months) solar activity in the latter stage of
solar cycle 23 and compare to observations from SORCE/SIM and other
datasets. We will comment on the degree of redundancy in parts of
the solar spectrum and how this could affect what wavelengths and
bandpasses in the spectrum are important for observing programs.
Title: Toward a Virtual Solar-Terrestrial Observatory
Authors: Fox, P. A.; Garcia, J.; West, P.
Bibcode: 2004AAS...204.7001F
Altcode: 2004BAAS...36..795F
The VSTO is proposed to be a scalable environment for searching,
integrating, and analyzing databases distributed over the Internet. The
VSTO would comprise a system of data, model, tool and material archives
containing items from space- and ground-based instruments, individual
and community modeling efforts, taken from NCAR, US universities
and international sources, and from NSF- and NASA-funded groups. A
key element of the VSTO is an integrated data-mining and analysis
capability that can be applied both across and within databases. The
capabilities of a VSTO are intended to be available to a wider
community of scientists, educators, and the public and thus is intended
to be a natural conduit for education and public outreach in solar
solar-terrestrial and space physics. This presentation will outline the
key functionality, proposed architecture and technologies that will
be used in assembling the VSTO. We will also present past experience
in building elements of data and collaborations system and the lessons
learned. NCAR is sponsored by the National Science Foundation.
Title: The SunRISE solar synthesis model
Authors: Fox, P.; White, O. R.; Fontenla, J. M.
Bibcode: 2004cosp...35.2337F
Altcode: 2004cosp.meet.2337F
We present a spectral synthesis approach to making quantitative
estimates of UV and EUV spectral variability. We combine the
identification of solar surface structures from the analysis of images
from the PSPT and spectromagnetograms from NSO/KP, with the theory
for emission, absorption, and transfer of radiation in the solar
atmosphere. We will present the latest results from the spectral
synthesis model and compare them to related observations and comment
on their accuracy and applicability to use in terrestrial atmoshpere
studies. NCAR is sponsored by the National Science Foundation. This
work is partly sponsored by the NSF RISE program.
Title: Status of ISO-DIS 21348 for synthetic solar spectral irradiance
models.
Authors: Fox, P.
Bibcode: 2004cosp...35.2335F
Altcode: 2004cosp.meet.2335F
We present the current methodology in place for our development and
production use of synthetic models of the solar spectral irradiance
(Fontenla et al. 1999, Fox et al. 2004). The goal of the synthesis is
the successful combination of realistic representations of the observed
solar disk with semi-empirical models and the theory for calculation
of a mixed line+continuum solar spectrum in specific spectral bands in
the UV, visible, and near-IR. Each stage of the process is discussed
within the context of compliance with the DIS. The complete model
development includes a number of stages: analysis of high precision
photometric solar images and magnetograms, calculation of emission,
absorption, and transfer of radiation in the solar atmosphere based on
semi-empirical thermodynamics models and several sources of atomic and
molecular data, and the production of databases of component models
of the solar spectral radiances, and irradiances for ranges of solar
magnetic activity levels. NCAR is sponsored by the National Science
Foundation. This work is partly sponsored by the NSF RISE program.
Title: Solar irradiance variability - comparison of models and
observations
Authors: Fox, P. A.; Fontenla, J. M.; White, O. R.
Bibcode: 2004AdSpR..34..231F
Altcode:
Over the past decade, regular measurement programs for parts of the
solar spectrum have been established. In recent years substantial
progress has also been made on the physical understanding of these
measurements. To refine our understanding and to make quantitative
estimates of this variability requires a study of the entire solar
spectrum. Our approach to this requirement is to combine empirical
image analysis with the theory for emission, absorption, and transfer
of radiation in the solar atmosphere. The goal is the successful
combination of observed solar images with semi-empirical models and
theory for calculation of a mixed line + continuum spectrum emitted from
realistic representations of the observed solar disk. We present the
latest results from the SunRISE spectral synthesis model in specific
spectral bands in the UV, visible, and near-IR, and compare them to
related observations.
Title: Solar Variability and its Effects on Climate. Geophysical
Monograph 141
Authors: Pap, Judit M.; Fox, Peter; Frohlich, Claus; Hudson, Hugh S.;
Kuhn, Jeffrey; McCormack, John; North, Gerald; Sprigg, William; Wu,
S. T.
Bibcode: 2004GMS...141.....P
Altcode:
This monograph presents a state-of-the-art description of the most
recent results on solar variability and its possible influence on the
Earth's climate and atmosphere. Our primary goal in doing so is to
review solar energy flux variations (both electromagnetic and particle)
and understand their relations to solar magnetic field changes and
global effects, their impact on different atmospheric layers, and—as
a collaboration of scientists working on solar-terrestrial physics—to
note unresolved questions on an important interdisciplinary area. One of the highest-level questions facing science today is whether
the Earth's atmosphere and climate system changes in a way that we
can understand and predict. The Earth's climate is the result of
a complex and incompletely understood system of external inputs and
interacting parts. Climate change can occur on various time scales as a
consequence of natural variability—including solar variability—or
anthropogenic causes, or both. The Sun's variability in the form
of sunspots and related magnetic activity has been the subject of
careful study ever since the earliest telescopic observations. High
precision photometric observations of solar-type stars clearly show that
year-to-year brightness variations connected with magnetic activity
are a widespread phenomenon among such stars. As our nearest star,
the Sun is the only star where we can observe and identify a variety of
structures and processes which lead to variations in the solar energy
output, in both radiative and particle fluxes. Studying event tiny
changes in solar energy flux variations may teach us about internal
processes taking place in the Sun's convective zone and below.
Title: Redundancy and variability across the solar spectrum.
Authors: Fox, P.; White, O. R.
Bibcode: 2004cosp...35.2338F
Altcode: 2004cosp.meet.2338F
Intensities in the solar spectrum are fundamentally redundant (meaning
that the shape of the spectrum and its variation in magnitude for
different levels of activity and disk position, is similiar over
certain wavelength ranges. There are three reasons for this: 1)
The solar photosphere is close to local thermodynamic equilibrium
(LTE) and not very far from radiative equilibrium; therefore, the
spectral distribution is close to a Planck function. Under conditions
of radiative equilibrium, the entire spectrum will be determined by
a single variable, the effective temperature. 2) Radiation emergent
from a stellar atmosphere does not originate from a single level in the
atmosphere, rather it is the accumulation of radiation from inside the
atmosphere along the line of sight to the observer. The basic function
in this accumulation process is the contribution (or source) function
which has a maximum near unit optical depth and a width (FWHM) spanning
about two density scale heights. 3) The wavelength dependence of the
opacity allows this contribution function to shift up and down in the
atmosphere according to whether the opacity increases or decreases,
respectively. Since the photospheric temperature decreases outward,
such shifts in the region of radiation formation cause changes in
the emergent intensity. If the opacity had no wavelength dependence,
the peak of the contribution function would be at the same optical
depth for all wavelengths and the redundancy in wavelength would
be limited to narrow bands determined solely by the width of the
contribution function. However, under realistic solar conditions,
our synthesis calculations show that radiation at 500 nm is formed at
the same radiation temperature and depth as that at about 1.3 microns
(for example). The object of this study is to determine how a particular
(smaller) wavelength region may represent a wider band or other bands in
the solar spectrum. To exploit the redundancy in the spectrum requires
an understanding of how the relative variability in well defined
wavelength regions responds to changing solar activity and whether
the correspondence depends on the time scale of the solar activity,
e.g. that of active region emergence compared to the solar cycle
itself. We present details of the investigation of these factors. NCAR
is sponsored by the National Science Foundation. This work is partly
supported by the NSF RISE program.
Title: Solar Activity and Irradiance Variations
Authors: Fox, Peter
Bibcode: 2004GMS...141..141F
Altcode:
This chapter explores the relation between solar activity and solar
irradiance variability and reviews the current state of models of the
total and spectral irradiance and variability, including uncertainties
in both the theory, assumptions, free parameters, and inputs. Over
the past decade, regular measurement programs for parts of the solar
reference spectrum have been established and the physical understanding
of these measurements is rapidly improving. We discuss all of the
present modeling approaches which range from simple time series proxy
models for the total solar irradiance to the spectral irradiance which
may use a combination of semi-empirical models and empirical image
analysis with the theory for line-by-line calculation of emission,
absorption, and transfer of radiation in the solar atmosphere. This
chapter starts with some definitions and proceeds to a recent history
of irradiance models. Next, attention is given to similarities and
differences between the models and the common assumptions related
to solar activity influences and then the different types of models
are presented along with some recent results and their comparison
to extant observations. The chapter concludes with an assessment of
the current state of models, what the present level of accuracy and
precision they can achieve, their uncertainties and what advances are
in the near future.
Title: Preface
Authors: Pap, Judit M.; Fox, Peter; Fröhlich, Claus; Hudson, Hugh S.;
Kuhn, Jeffrey; McCormack, John; North, Gerald; Sprigg, William; Wu,
S. T.
Bibcode: 2004GMS...141D...7P
Altcode:
This monograph presents a state-of-the-art description of the most
recent results on solar variability and its possible influence on the
Earth's climate and atmosphere. Our primary goal in doing so is to
review solar energy flux variations (both electromagnetic and particle)
and understand their relations to solar magnetic field changes and
global effects, their impact on different atmospheric layers, and—as
a collaboration of scientists working on solar-terrestrial physics—to
note unresolved questions on an important interdisciplinary area. One of the highest-level questions facing science today is whether
the Earth's atmosphere and climate system changes in a way that we
can understand and predict. The Earth's climate is the result of
a complex and incompletely understood system of external inputs and
interacting parts. Climate change can occur on various time scales as a
consequence of natural variability—including solar variability—or
anthropogenic causes, or both. The Sun's variability in the form
of sunspots and related magnetic activity has been the subject of
careful study ever since the earliest telescopic observations. High
precision photometric observations of solar-type stars clearly show that
year-to-year brightness variations connected with magnetic activity
are a widespread phenomenon among such stars. As our nearest star,
the Sun is the only star where we can observe and identify a variety of
structures and processes which lead to variations in the solar energy
output, in both radiative and particle fluxes. Studying even tiny
changes in solar energy flux variations may teach us about internal
processes taking place in the Sun's convective zone and below.
Title: A Prototype for a Virtual Solar-Terrestrial Observatory
Authors: Fox, P. A.; Garcia, J.; West, P.
Bibcode: 2003AGUFM.U22A0015F
Altcode:
The VSTO is proposed to be a scalable environment for searching,
integrating, and analyzing databases distributed over the Internet. The
VSTO would comprise a system of data, model, tool and material archives
containing items from space- and ground-based instruments, individual
and community modeling efforts, taken from NCAR, US universities
and international sources, and from NSF- and NASA-funded groups. A
key element of the VSTO is an integrated data-mining and analysis
capability that can be applied both across and within databases. The
capabilities of a VSTO are intended to be available to a wider
community of scientists, educators, and the public and thus is
intended to be a natural conduit for education and public outreach
in solar solar-terrestrial and space physics. This presentation will
outline the key functionality, proposed architecture and technologies
that will be used in assembling the VSTO. We will also present past
experience in building elements of data and collaborations system and
the lessons learned.
Title: Physical Synthesis of the Solar Radiance, a Tool for
Understanding Spectral Irradiance
Authors: Fontenla, J. M.; White, O. R.; Evrett, E. H.; Rottman, G.;
Fox, P.; Harder, J.; Davis, S.
Bibcode: 2003AGUFMSH12A1157F
Altcode:
In this paper we summarize the current status of our physical modeling
of the solar radiation and briefly describe the key improvements
in the methods we use to compute synthetic solar spectrum. We use 7
solar atmosphere models for summarizing the features observed on the
solar disk, and we compute the emitted spectrum at 10 positions on
the disk. These models and disk positions are intended to cover the
significant features of quiet and active Sun that are linked with solar
irradiance variations. The calculation is extremely detailed and each
of the many thousands of spectral lines is fully resolved so that the
spectra can be convolved with any instrument function and compared with
observations at high or low spectral resolution. Our version 1 code
and models provide very good agreement with observations of spectral
irradiance between ∼450 and ∼1000 nm, but is not accurate outside
that range. We describe the basic procedures used in Version 1 and
the differences with the procedures that will be used in Version 2
for improving the synthesis accuracy over a more extended wavelength
range. We expect that version 2 will be a major step in understanding
the solar spectral irradiance and its variations beyond what is
currently available from any solar irradiance models.
Title: On the possibility of large axion decay constants
Authors: Banks, Tom; Dine, Michael; Fox, P. J.; Gorbatov, E.
Bibcode: 2003JCAP...06..001B
Altcode: 2003hep.th....3252B
The decay constant of the QCD axion is required by observation to be
small compared with the Planck scale. In theories of `natural inflation'
and certain proposed anthropic solutions of the cosmological constant
problem it would be interesting to obtain a large decay constant for
axion-like fields from microscopic physics. String theory is the only
context in which one can sensibly address this question. Here we survey
a number of periodic fields in string theory in a variety of string
vacua. In some examples, the decay constant can be parametrically
larger than the Planck scale but the effective action then contains
appreciable harmonics of order fA/Mp. As a result,
these fields are no better inflaton candidates than Planck scale axions.
Title: Physical Modeling of the Solar Radiation, Current Status
and Prospects
Authors: Fontenla, J. M.; Avrett, E. H.; Goodman, M.; White, O. W.;
Rottman, G.; Fox, P.; Harder, J.
Bibcode: 2003SPD....34.0301F
Altcode: 2003BAAS...35..808F
Physical models that include full NLTE radiative transfer as well as
particle transport and MHD processes are the key to understanding the
solar radiative output and also are essential to our understanding
of heating and the dynamics of the solar atmosphere, in particular
for chromospheric layers. SOHO observations show that chromospheric
emission lines do not vary dramatically in time and that chromospheric
heating, even in the quiet Sun, is not simply due to, p-modes induced,
strong shock waves passing through the chromosphere. The physics of
the chromospheric heating is more complicated and remains elusive. The
chromospheric and coronal heating are likely closely related to the
dynamics in these regions as well as in the thin chromosphere-corona
transition region since they are a coupled system. Solar atmospheric
heating and dynamics are strongly affected by the magnetic fields and
MHD mechanisms must be considered. Models for the upper photosphere
and chromosphere should also consider NLTE radiative transfer and
radiative losses as well as particle transport processes including
tensor electric resistivity with magnetic field. Models for the
transition region and coronal layers must also consider particle
diffusion. In this paper we show schematically: 1) the current state
of our research on modeling observed features of the solar structure
and their radiative signatures; 2) the application of this modeling
to the Earth solar irradiance and comparisons with observations; 3)
the key achievements and the needed improvements of the modeling; 4)
our plans for future research starting from ab initio semi-empirical
models based on observations, and, while maintaining the agreement with
relevant observations, moving towards physically consistent models that
include key MHD processes thereby replacing empirical constraints by
physically consistent processes and boundary conditions.
Title: Solar variability and its effects on climate
Authors: Pap, Judit M.; Fox, Peter A.
Bibcode: 2003GMS...141.....P
Altcode:
No abstract at ADS
Title: Interoperable Data Delivery in Solar-terrestrial Applications:
CEDARWEB and OpENDAP.
Authors: Fox, P. A.
Bibcode: 2002AGUFMSH51A0419F
Altcode:
The High Altitude Observatory (HAO) division of NCAR investigates
the sun and the earth's space environment, focusing on the physical
processes that govern the sun, the interplanetary environment, and
the earth's upper atmosphere. We present details on how a set of data
systems supported by HAO and collaborators has driven the implementation
of services around the Data Access Protocol (DAP) originating in the
Distributed Oceanographic Data System (DODS) project. The outgrowth
of this is the OpENDAP - an open source project to provide reference
implementations of the DAP and its core services. We will present the
recent design and development details of the CEDARWEB (NSF program for
Coupled Energetics and Dynamics of Atmospheric Regions) service built
around the DAP, including interfaces to common application programs,
like the Interactive Data Language, the web, and server side data
format translation and related services. We also present examples
of how the interoperability in the assembly of this system is being
used in other science discipline and technology areas: the Radiative
Inputs from Sun to Earth program, the Earth System Grid II project,
and the Space Physics and Aeronomy Collaboratory.
Title: Solar Irradiance Variability - comparison of models and
observations
Authors: Fox, P. A.
Bibcode: 2002AAS...200.5708F
Altcode: 2002BAAS...34..737F
Over the past decade, regular measurement programs for parts of the
solar spectrum have been established. In recent years substantial
progress has also been made on the physical understanding of these
measurements. To refine our understanding and to make quantitative
estimates of this variability requires a study of the entire solar
spectrum. Our approach to this requirement is to combine empirical
image analysis with the theory for emission, absorption, and transfer
of radiation in the solar atmosphere. The goal is the successful
combination of observed solar images with semi-empirical models and
theory for calculation of a mixed line+continuum spectrum emitted
from realistic representations of the observed solar disk. We
present the latest results from the SunRISE spectral synthesis
model in specific spectral bands in the UV, visible, and near-IR,
and compare them to related observations (including those from the
RISE/PSPT instrument). NCAR is sponsored by the National Science
Foundation. This work is sponsored by the NSF RISE program.
Title: Solar irradiance variability - comparison of models and
observatons
Authors: Fox, P.
Bibcode: 2002cosp...34E3254F
Altcode: 2002cosp.meetE3254F
Over the past decade, regular measurement programs for parts of the
solar spectrum have been established. In recent years substantial
progress has also been made on the physical understanding of these
measurements. To refine our understanding and to make quantitative
estimates of this variability requires a study of the entire solar
spectrum. Our approach to this requirement is to combine empirical
image analysis with the theory for emission, absorption, and transfer
of radiation in the solar atmosphere. The goal is the successful
combination of observed solar images with semi-empirical models and
theory for calculation of a mixed line+continuum spectrum emitted from
realistic representations of the observed solar disk. We present the
latest results from the SunRISE spectral synthesis model in specific
spectral lines and bands in the UV, visible, and near-IR, and compare
them to related observations. NCAR is sponsored by the National Science
Foundation. This work is sponsored by the NSF RISE program.
Title: The Radarsat-2 Mission: New Modes and Techniques
Authors: Fox, P.
Bibcode: 2002iaf..confE..89F
Altcode:
No abstract at ADS
Title: Sunspot Bright Rings: Evidence from Case Studies
Authors: Rast, M. P.; Meisner, R. W.; Lites, B. W.; Fox, P. A.; White,
O. R.
Bibcode: 2001ApJ...557..864R
Altcode:
We present evidence, from both the Precision Solar Photometric Telescope
and the Advanced Stokes Polarimeter, for a ring of enhanced continuum
intensity surrounding large isolated sunspots. We do not attempt to
evaluate the frequency of the phenomenon based on a large sample of
spots but instead concentrate on illustrative best-case examples. The
rings are about 0.5%-1.0% brighter in red and blue continuum (10 K
warmer) than the surrounding photosphere and extend about one sunspot
radius outward from the outer penumbral boundary. Most of the excess
radiation is not directly associated with the strongest regions of Ca II
K emission surrounding the spots or with measurable vertical magnetic
field when such measurements are available. Moreover, the temporal
evolution of the Ca II K and continuum emission in the ring differ,
with the continuum intensity evolving on a shorter timescale. This
suggests a convective origin for the bright ring, although a role
for weaker, more diffuse magnetic fields cannot be ruled out. While
we have inferred that only about 10% of the radiant energy missing
from the sunspot is emitted through the bright ring, even this small
enhancement may be significant to our understanding of subsurface
sunspot structure and energy transport.
Title: Data From the Precision Solar Photometric Telescope (Pspt)
in Hawaii From March 1998 to March 1999
Authors: White, Oran R.; Fox, Peter A.; Meisner, Randy; Rast, Mark
P.; Yasukawa, Eric; Koon, Darryl; Rice, Crystal; Lin, Haosheng; Kuhn,
Jeff; Coulter, Roy
Bibcode: 2000SSRv...94...75W
Altcode:
Two Precision Solar Photometric Telescopes (PSPT) designed and built at
the U.S. National Solar Observatory (NSO) are in operation in Rome and
Hawaii. A third PSPT is now in operation the NSO at Sunspot, NM. The
PSPT system records full disk solar images at three wavelengths:
K line at 393.3 nm and two continua at 409 nm and 607 nm throughout
the observing day. We currently study properties of limb darkening,
sunspots, and network in these images with particular emphasis on data
taken in July and September 1998. During this period, the number of
observations per month was high enough to show directional properties
of the radiation field surrounding sunspots. We show examples of our
PSPT images and describe our study of bright rings around sunspots.
Title: Extreme solar cycle variability in strong lines between 200
and 400 NM
Authors: White, Oran R.; Fontenla, John; Fox, Peter A.
Bibcode: 2000SSRv...94...67W
Altcode:
Our study of solar cycle irradiance variability in the UV between
200 and 400 nm requires a detailed knowledge of the composition of
the solar spectrum in this wavelength range. We compute the synthetic
spectrum from 250 to 300 nm and compare it with ATLAS3 and SOLSTICE
observations. Synthetic solar spectra for solar minimum and maximum
conditions show large variations in broad, strong UV lines. Strong
lines of FeI between 260 nm and 264 nm show increases between 0.4×
and 3×in their max/min ratio. Our ``broad lines'' database shows 167
lines with similar properties between 200 nm and 400 nm. Our results
raise issues of the importance of such large variability in narrow
bands and the difficulty of detection in measurements with spectral
resolutions of 1 nm.
Title: Geophysical and Astrophysical Convection.
Authors: Fox, Peter A.; Kerr, Robert M.
Bibcode: 2000gac..conf.....F
Altcode:
No abstract at ADS
Title: Erratum: Joint Instability of Latitudinal Differential
Rotation and Toroidal Magnetic Fields below the Solar Convection
Zone. II. Instability for Toroidal Fields That Have a Node between
the Equator and Pole
Authors: Gilman, Peter A.; Fox, Peter A.
Bibcode: 2000ApJ...534.1020G
Altcode:
There is a repeated error in certain equations in the papers by Peter
A. Gilman and Peter A. Fox, ``Joint Instability of Latitudinal
Differential Rotation and Toroidal Magnetic Fields below the
Solar Convection Zone. II. Instability for Toroidal Fields That
Have a Node between the Equator and Pole'' (510, 1018 [1999])
(GF) Mausumi Dikpati and Peter A. Gilman, ``Joint Instability
of Latitudinal Differential Rotation and Concentrated Toroidal
Fields below the Solar Convection Zone'' (512, 417 [1999]) (DG)
and Peter A. Gilman and Mausumi Dikpati, ``Joint Instability of
Latitudinal Differential Rotation and Concentrated Toroidal Fields
below the Solar Convection Zone. II. Instability of Narrow Bands
at All Latitudes'' (528, 552 [2000]) (GD). In GF, equation (3), DG,
equation (24), and GD, equation (3), all are missing an additive term
that multiplies the variable H. The correct total factor multiplying
H is {1/(1-μ2) ( 2 - m2/(1-μ2)
+ 1/S[2c(ωo-c) + μ d/dμ(S/(1-μ2)]} The
second term, involving S in the denominator, is missing in these
papers. As a consequence, the expression for k2, shown
in equation (6) of GF and equation (10) of DG, is also missing
this term. The correct expression for k2 in both cases
is 1/(1-μ2) ( 2 - m2/(1-μ2) +
((1/2S)(d2S/dμ2)) + 1/S[2c(ωo-c) +
μ d/dμ(S/(1-μ2)] No results or conclusions are affected in
any of these papers, because the equations containing errors are used
only to identify the location of singular points, where the effective
wavenumber increases without bound. All of these singular points are the
same in the erroneous forms as in the correct forms, being determined
principally by the roots of S. But obviously, if the erroneous forms
are used for other purposes, incorrect conclusions might be reached. The
authors are indebted to Paul Cally for discovering this error.
Title: Data from the Precision Solar Photometric Telescope (PSPT)
in Hawaii from March 1998 to March 1999
Authors: White, Oran R.; Fox, Peter A.; Meisner, Randy; Rast, Mark
P.; Yasukawa, Eric; Koon, Darryl; Rice, Crystal; Lin, Haosheng; Kuhn,
Jeff; Coulter, Roy
Bibcode: 2000svc..book...75W
Altcode:
No abstract at ADS
Title: Extreme Solar Cycle Variability in Strong Lines Between 200
and 400 nm
Authors: White, Oran R.; Fontenla, John; Fox, Peter A.
Bibcode: 2000svc..book...67W
Altcode:
No abstract at ADS
Title: Bright rings around sunspots
Authors: Rast, M. P.; Fox, P. A.; Lin, H.; Lites, B. W.; Meisner,
R. W.; White, O. R.
Bibcode: 1999Natur.401..678R
Altcode:
There are two possible explanations for why sunspots are dark: the
partial suppression by the sunspot magnetic fields of convective energy
transport from the underlying layers, or the removal of energy from
the sunspot by enhanced hydromagnetic wave radiation. Both processes
would reduce the energy emitted radiatively. The first explanation
is currently favoured, and predicts that the blocked energy should
show up as a bright ring around the spot, with the actual brightness
of the ring sensitive to details of solar convective transport and
sunspot structure. Previous searches for these bright rings were
inconclusive because of the presence of bright, vertical magnetic
flux tubes near the spots, and a lack of sufficient precision in the
observations. Here we report high-photometric-precision observations
of bright rings around eight sunspots. The rings are about 10K warmer
than the surrounding photosphere and extend at least one sunspot
radius out from the penumbra. About 10% of the radiative energy
missing from the sunspots is emitted through the bright rings. We
also report observations of a second set of sunspots, for which
simultaneous magnetic field measurements demonstrate that the rings
are not associated with vertical flux tubes.
Title: Joint Instability of Latitudinal Differential Rotation
and Toroidal Magnetic Fields below the Solar Convection
Zone. III. Unstable Disturbance Phenomenology and the Solar Cycle
Authors: Gilman, P. A.; Fox, P. A.
Bibcode: 1999ApJ...522.1167G
Altcode:
We analyze additional solutions for the two-dimensional instability of
coexisting differential rotation and toroidal magnetic fields, organized
in families with fixed ratios ER of magnetic to kinetic energy in the
unperturbed state. Solutions are found for a wide range of differential
rotation amplitudes found in the solar tachocline, for toroidal fields
that have a node that ranges in latitude from the pole to the equator,
as we expect to exist in the Sun through a sunspot cycle. Fixed ER is a
proxy for nonlinear saturation of the solar dynamo due to the reaction
of electromagnetic body forces. Since the saturation ratio is not known
from either theory or observations, we find solutions in the range
0.1<=ER<=30, corresponding to peak toroidal fields in the solar
tachocline of between about 8×103 to 1.4×105
G. We focus on properties of the unstable disturbances that could test
the hypothesis that such disturbances in the solar tachocline provide
a template for surface features. We show that the symmetry of magnetic
pattern about the equator could switch at one or more phases of the
magnetic cycle, and for high ER a switch could also occur between two
antisymmetric patterns of different latitudinal profiles. In the former
case, the pattern rotation rate would be unchanged, but there would be
a sudden longitudinal phase shift in one or both hemispheres. In the
latter case, there would be no phase shift but instead a substantial
change in the rotation rate of the observed magnetic pattern. For a
given mode symmetry and type, the rotation rate is the same at all
latitudes, with the rate being close to that of the local rotation of
the plasma at the latitude where the disturbance amplitude peaks. For
ER<~1, the disturbance magnetic patterns have significant tilts
upstream away from the equator, reminiscent of similar patterns in
synoptic magnetograms. Sharp changes with latitude in the differential
rotation and toroidal field are associated with ``critical points'' in
the system, where the Doppler-shifted disturbance rotation equals the
local (angular) Alfvén speed. These migrate toward the equator with the
toroidal field node but increasingly lag it. The higher the magnetic
energy for a given differential rotation, the closer the equator
is approached. If these sharp changes in differential rotation and
toroidal field are related to the torsional oscillations and latitudes
of sunspots, then these solutions favor large toroidal fields in the
tachocline, of peak amplitude at least 6×104 G.
Title: Calculation of Solar Irradiances. I. Synthesis of the Solar
Spectrum
Authors: Fontenla, Juan; White, Oran R.; Fox, Peter A.; Avrett,
Eugene H.; Kurucz, Robert L.
Bibcode: 1999ApJ...518..480F
Altcode:
Variations in the total radiative output of the Sun as well as
the detailed spectral irradiance are of interest to terrestrial
and solar-stellar atmosphere studies. Recent observations provide
measurements of spectral irradiance variations at wavelengths in the
range 1100-8650 Å with improved accuracy, and correlative studies
give procedures for estimating the spectral irradiance changes from
solar activity records using indicators such as those derived from
Ca II K and Mg II indices. Here we describe our approach to physical
modeling of irradiance variations using seven semiempirical models to
represent sunspots, plage, network, and quiet atmosphere. This paper
gives methods and details, and some preliminary results of our synthesis
of the variations of the entire irradiance spectrum. Our calculation
uses object-oriented programming techniques that are very efficient
and flexible. We compute at high spectral resolution the intensity
as a function of wavelength and position on the disk for each of the
structure types corresponding to our models. These calculations include
three different approximations for the line source function: one suited
for the very strong resonance lines where partial redistribution
(PRD) is important, another for the most important nonresonance
lines, and another approximation for the many narrow lines that are
provided in Kurucz's listings. The image analysis and calculations
of the irradiance variation as a function of time will be described
in a later paper. This work provides an understanding of the sources
of variability arising from solar-activity surface structures. We
compute the Lyα irradiance to within 3% of the observed values. The
difference between our computations and the Neckel & Labs data is 3%
or less in the near-IR wavelengths at 8650 Å, and less than 1% in the
red at 6080 Å. Near 4100 Å we overestimate the irradiance by 9%-19%
because of opacity sources missing in our calculations. We also compute
a solar cycle variability of 49% in the Lyα irradiance, which is very
close to observed values. At wavelengths between 4100 Å and 1.6 μm,
we obtain spectral irradiance variations ranging from -0.06% to 0.46%
in the visible--the higher values correspond to the presence of strong
lines. The variability in the IR between 1.3 and 2.2 μm is ~-0.15%.
Title: Joint Instability of Latitudinal Differential Rotation
and Toroidal Magnetic Fields below the Solar Convection
Zone. II. Instability for Toroidal Fields that Have a Node between
the Equator and Pole
Authors: Gilman, Peter A.; Fox, Peter A.
Bibcode: 1999ApJ...510.1018G
Altcode:
We generalize results of Gilman and Fox to unperturbed toroidal
fields that have a node somewhere between the equator and the
pole as we speculate the Sun's field to have for most phases of
its magnetic cycle. We use the same solution method as in Gilman
and Fox, namely Legendre polynomial expansion and matrix inversion
to solve for the eigenvalues and eigenfunctions. The solutions are
structured around certain singular or critical points of the suitably
transformed and combined vorticity and induction equations. There
are singular points at the poles, and singularities where
ω0-cr=+/-α0, in which ω0
is the local rotation rate, cr is the longitudinal phase
speed of an unstable wave, and α0 is an angular measure of
the toroidal field. We survey the instability as a function of toroidal
field profile and amplitude as well as differential rotation amplitude,
thereby examining reference states that could be characteristic of
most phases of the solar cycle, and most depths within the rotational
shear layer just below the base of the solar convection zone. As
found in Gilman and Fox, instability occurs for a wide range of both
toroidal fields and differential rotations. Differential rotation is
again the primary energy source for growing modes when the toroidal
field is weak, and the toroidal field is the primary source when it
is strong. Unlike in Gilman and Fox, here modes of both symmetries
about the equator are unstable for low and high toroidal fields,
and for high fields a second antisymmetric mode appears. Which mode
symmetry is favored for low fields depends in detail on the relative
amplitudes of differential rotation and toroidal field. For low toroidal
fields (unstable) modes of both symmetries are energetically active
(extracting energy from the unperturbed state) only poleward of the
node and an adjacent singularity, but are coupled to energetically
neutral velocity perturbations equatorward of that singular point. In
transition to higher field strengths, those velocity patterns are damped
out when two additional singular points appear in the system, but the
energetically active high-latitude disturbances remain. By contrast
the second antisymmetric mode is energetically active equatorward
of the toroidal field node and closely adjacent singular points,
but is coupled to an energetically neutral pattern of both velocities
and magnetic fields on the poleward side. As in Gilman and Fox,
we find narrow-latitude bands of sharp changes in both differential
rotation and toroidal magnetic field that migrate toward the equator
with increasing field strength, but are bounded in their migration by
the latitude of the toroidal field node. These sharp changes are always
at the locations of the singular points of the system and represent
narrow domains where both kinetic and magnetic energy are being
extracted from the reference state to drive the instability. We
interpret the instability as a form of resonant overreflection between
singular points, analogous to what happens in stratified shear flow,
as described for example by Lindzen. The instability may contribute
to determining the latitudinal and longitudinal distribution of active
regions and other large-scale, magnetic features on the Sun, as well as
enable a degree of synchronization of the evolution of the solar cycle
between low latitudes and high, and between north and south hemispheres.
Title: Forecast update for activity cycle 23 from a dynamo-based
method
Authors: Sofia, Sabatino; Fox, Peter; Schatten, Kenneth
Bibcode: 1998GeoRL..25.4149S
Altcode:
In this paper we update a prediction of the solar activity for cycle
23 on the basis of a general framework derived from simple dynamo
considerations. We estimate an expected maximum smoothed International
Sunspot Number of 143±30, or a smoothed 2800 MHz radio flux (F10.7)
of 190±30×10-22 Watts/m²/Hz. These values should allow
us to test the reliability of the various forecasting methods.
Title: Coronal Holes and the Polar Field Reversals
Authors: Fox, P.; McIntosh, P.; Wilson, P. R.
Bibcode: 1998SoPh..177..375F
Altcode:
A description of the reversal of the solar north polar magnetic field
during cycle 22 is provided using polar projections which combine
the large-scale magnetic fields as inferred from Hα synoptic charts
and coronal holes mapped from Hei λ1083 nm spectroheliograms. These
plots are supported by polar plots of the magnetic fields derived from
synoptic magnetic field data from the Mount Wilson Observatory. The
coronal holes showed some unexpected evolutionary patterns in
relation to the polarity reversals, and these patterns appear to be
coordinated with changes in the global patterns of coronal holes and
the heliospheric current sheet, suggesting that the polar reversal
originates from global processes rather than from local magnetic flux
annihilation. Similar patterns have been observed in the reversal of
the southern polar magnetic field in cycle 22 and in both hemispheres
in cycle 21. The consequences of these findings for the solar dynamo
process are discussed.
Title: Joint Instability of Latitudinal Differential Rotation and
Toroidal Magnetic Fields below the Solar Convection Zone
Authors: Gilman, Peter A.; Fox, Peter A.
Bibcode: 1997ApJ...484..439G
Altcode:
Below the convection zone, where the stratification is radiatively
controlled, large-scale motions should be mainly horizontal, i.e., in
spherical shells due to the stabilizing effect of negative buoyancy
on radial displacements. Watson showed that the observed surface
solar differential rotation is at the threshold for instability to
horizontal disturbances. Therefore, since helioseismology tells us
the latitudinal differential rotation below the convection zone is
less than the surface value, the profile should be stable too. We show
that in the presence of a broad, nonuniform toroidal field the solar
differential rotation is unstable. This is true for a wide range of
kinetic and magnetic energies of the unperturbed state, from well below
equipartition to well above it. We find instability for essentially
all values of differential rotation and toroidal fields for which
we are able to find converged solutions. The instability appears to
occur only for longitudinal wave number 1. Disturbance symmetries
about the equator and profiles in latitude depend on the amplitude of
the toridal field. Peak e-folding times are a few months. The primary
energy source for the instability is differential rotation for low
field strengths and the toroidal field for high field strengths. The
mechanism of energy release from the differential rotation is the
poleward transport of angular momentum, by the Maxwell stress rather
than the Reynolds stress. For the profiles studied, the Reynolds stress
is almost always trying to rebuild differential rotation, the exact
opposite of the nonmagnetic case. Second-order perturbation theory
predicts that the unstable modes produce zonal jets and fine structure
in the toroidal field, the latitude of which migrates toward the equator
with increasing magnetic field strength. The instability we have found
may play a role in the solar dynamo, although being two-dimensional,
it cannot produce a dynamo by itself. Mixing of angular momentum caused
by the instability could allow achievement of equilibrium of the solar
tachocline hypothesized by Spiegel & Zahn.
Title: Joint Instability of Differential Rotation and Toroidal
Magnetic Fields below the Solar Convection Zone, II
Authors: Gilman, P. A.; Fox, P.
Bibcode: 1997SPD....28.0212G
Altcode: 1997BAAS...29..895G
At the 1996 AAS/SPD meeting in Madison we reported first results for
the joint instability of differential rotation and toroidal magnetic
fields to 2D disturbances (see also Gilman and Fox, Paper I, July 20
1997 issue of ApJ). This analysis was for the toroidal field profile
B=a*sin(LAT)cos(LAT). This paper reports results for the profile
B=(a*sin(LAT)+b*(sin(LAT))(3) ))cos(LAT), which, with b<-a<0,
allows for a node in the toroidal field at latitude arcsin (-a/b). This
generalization is of interest because we should expect such a node to
appear and migrate equatorward as the sun proceeds from one sunspot
cycle to the next. As with the simpler profile, instability occurs
for virtually all differential rotation amplitudes, and all toroidal
field amplitudes and shapes, and remains confined to disturbances
with longitudinal wave number m=1. For a, b>0, the instability is
enhanced for the same a compared to the b=0 case, particularly in high
latitudes. For 0>b>-a (so no node is present) the instability is
similar to the b=0 case but with diminished growth rates, due to the
reduction of toroidal fields at high latitudes. At b=-a, the symmetric
mode of instability vanishes, but the antisymmetric mode remains. For
b<-a<0, both symmetric and antisymmetric modes are unstable, but
with disturbances confined largely to the domain poleward of the node,
unless the toroidal field energy greatly exceeds the kinetic energy of
differential rotation. Unstable disturbances spread and migrate toward
the equator as the field strength is increased and as the node is moved
equatorward. Thus, the instability may still contribute to the existence
of the solar butterfly diagram, and to other solar dynamo presses.
Title: Joint Instability of Latitudinal Differential Rotation and
Toroidal Magnetic Fields below the Solar Convection Zone
Authors: Gilman, Peter A.; Fox, Peter
Bibcode: 1996AAS...188.6916G
Altcode: 1996BAAS...28..938G
Below the convection zone, where the stratification is radiatively
controlled, large-scale motions should be mainly horizontal, i.e. in
spherical shells, due to the negative buoyancy radial displacements
would experience. Watson (G.A.F.D. 16, 285, 1981) showed that
the observed surface solar differential rotation is right at the
boundary for instability to horizontal disturbances. Therefore,
since helioseismology tells us the latitudinal differential rotation
below the convection zone is less than the surface value, it should be
stable. We show that in the presence of a broad, nonuniform toroidal
field this differential rotation is unstable. This is true for a wide
range of kinetic and magnetic energies of the unperturbed state, from
well below equipartition, to values above it. The instability appears
to occur only for longitudinal wave number 1. Its location in latitude
depends on details of the magnetic field profile. Generally, the primary
energy source for the instability is the differential rotation, but
the toroidal field also contributes. The mechanism of energy release
is the poleward transport of angular momentum, in a complex interplay
between the perturbation Reynolds and Maxwell stresses. This instability
may play a role in the solar dynamo, although being two- dimensional,
it cannot produce a dynamo by itself. Mixing of angular momentum caused
by the instability could allow achievement of equilibrium of the solar
tachocline hypothesized by Spiegel and Zahn.
Title: Modeling Convection in the Outer Layers of the Sun: A
Comparison with Predictions of the Mixing-Length Approximation
Authors: Kim, Yong-Cheol; Fox, Peter A.; Demarque, Pierre; Sofia,
Sabatino
Bibcode: 1996ApJ...461..499K
Altcode:
The mixing-length theory (MLT) approximation (Vitense 1953) is used in
most stellar evolution codes to describe the structure of the outer,
highly superadiabatic, layers of the Sun. This procedure is known to be
incorrect because of the MLT's inadequacies in describing convection and
because of the need to include the strong coupling between radiation
and convection in modeling this region. However, it is not known to
what extent and precisely in what ways the MLT approximation distorts
the structure of the highly superadiabatic peak in the outer convection
zone. The purpose of this paper is to compare the statistical results
of a more realistic three-dimensional numerical simulation of shallow
convection to the predictions of the MLT. The simulations differ from
the previous simulations of Chan & Sofia (1989) in that they include
a treatment of radiative transfer (in the diffusion approximation). The
layers are super- adiabatic and exhibit a sharp peak in the temperature
gradient. The results we derive from this simulation provide much more
information than conventional one-dimensional theories of convective
energy transport. We attempt to analyze or condense the information
from the simulation to be compared with a traditional "theory" in
an effort to establish how much a large eddy simulation can teach us
about mean convective transport theories. In this paper we chose to
use the mixing-length approximation for comparison. The standard
mixing-length approximation predicts a few linear relationships
between local thermodynamic and dynamic quantities, the coefficients
of which are functions of the mixing length. In these MLT relations,
the ratio of mixing length to the local pressure scale is assumed to
be constant over the entire convection zone, including the region
of high superadiabaticity where convective energy transfer becomes
less efficient.
Title: Modeling of Shallow and Inefficient Convection in the Outer
Layers of the Sun Using Realistic Physics
Authors: Kim, Yong-Cheol; Fox, Peter A.; Sofia, Sabatino; Demarque,
Pierre
Bibcode: 1995ApJ...442..422K
Altcode:
In an attempt to understand the properties of convective energy
transport in the solar convective zone, a numerical model has been
constructed for turbulent flows in a compressible, radiation-coupled,
nonmagnetic, gravitationally stratified medium using a realistic
equation of state and realistic opacities. The time-dependent,
three-dimensional hydrodynamic equations are solved with minimal
simplifications. The statistical information obtained from the present
simulation provides an improved understanding of solar photospheric
convection. The characteristics of solar convection in shallow regions
is parameterized and compared with the results of Chan & Sofia's
(1989) simulations of deep and efficient convection. We assess the
importance of the zones of partial ionization in the simulation and
confirm that the radiative energy transfer is negligible throughout
the region except in the uppermost scale heights of the convection
zone, a region of very high superadiabaticity. When the effects of
partial ionization are included, the dynamics of flows are altered
significantly. However, we confirm the Chan & Sofia result that
kinetic energy flux is nonnegligible and can have a negative value in
the convection zone.
Title: Calculation of Absolute Solar Irradiances and Their Variation
with Solar Activity
Authors: White, O. R.; Fontenla, J.; Fox, P.; Avrett, E. H.; Harvey, K.
Bibcode: 1995SPD....26..308W
Altcode: 1995BAAS...27..954W
No abstract at ADS
Title: Joint Discussion 13: Recent advances in convection theory
and modeling
Authors: Fox, Peter A.; Sofia, Sabatino
Bibcode: 1995ComAp..18...11F
Altcode:
No abstract at ADS
Title: Modeling Convection in the Outer Layers of the Sun : Constancy
of the Mixing Length Ratio near the Top of Convection Zone
Authors: Kim, Y. -C.; Fox, P. A.; Demarque, P.; Sofia, S.
Bibcode: 1995LIACo..32..195K
Altcode: 1995sews.book..195K
The purpose of this poster is to utilize the results of a numerical
simulation of solar convection based on a physically realistic
description of the shallow layers, and to compare the results with one
of the basic assumption of the standard mixing length approximation,
namely, a constant mixing length ratio throughout a convection zone.
Title: A subgrid-scale resistivity for magnetohydrodynamics
Authors: Theobald, Michael L.; Fox, Peter A.; Sofia, Sabatino
Bibcode: 1994PhPl....1.3016T
Altcode:
In this paper an investigation is made of dissipation of small
scale magnetic fields embedded in a turbulent gas flow using
magnetohydrodynamic (MHD) simulations, under conditions suggested by
the outer layers of the Sun, where heat is transported by turbulent
convection (as estimated by fluid and magnetic Reynolds numbers),
and dissipation is occurring on small scales. The large eddy
simulation approach is utilized along with a model for the unresolved
scales. Although a significant amount of work on modeling the small
scales has been done for hydrodynamic turbulence, the application to
MHD has received little attention. This paper specifically deals with
the small scale dissipation of magnetic fields and thus a so-called
subgrid-scale resistivity is postulated and then tested using a series
of two-dimensional numerical simulations. An attempt is made to clarify
the advantages and uncertainties of using this new formulation of
turbulent resistivity in MHD and suggest areas for improvement and
further application.
Title: Modelling of Shallow and Inefficient Convection in the Outer
Layers of the Sun Using Realistic Physics
Authors: -Cheol Kim, Yong; Fox, Peter A.; Sofia, Sabatino; Demarque,
Pierre
Bibcode: 1994astro.ph..3046.
Altcode: 1994astro.ph..3046K
In an attempt to understand the properties of convective energy
transport in the solar convection zone, a numerical model has been
constructed for turbulent flows in a compressible, radiation-coupled,
non-magnetic, gravitationally stratified medium using a realistic
equation of state and realistic opacities. The time-dependent,
three-dimensional hydrodynamic equations are solved with minimal
simplifications. The statistical information obtained from the present
simulation provides an improved understanding of solar photospheric
convection. The characteristics of solar convection in shallow
regions is parameterized and compared with the results of Chan and
Sofia's simulations of deep and efficient convection (Chan and Sofia
1989). We assess the importance of the zones of partial ionization
in the simulation, and confirm that the radiative energy transfer is
negligible throughout the region except in the uppermost scale heights
of the convection zone, a region of very high super-adiabaticity. When
the effects of partial ionization are included, the dynamics of flows
are altered significantly. However, we confirm the Chan and Sofia
result that kinetic energy flux is non-negligible and can have a
negative value in the convection zone.
Title: A Study of Small Scale Features zn Compressible
Magnetoconvection
Authors: Fox, Peter A.
Bibcode: 1994ASPC...68...62F
Altcode: 1994sare.conf...62F
No abstract at ADS
Title: Convection and Irradiance Variations
Authors: Fox, P. A.; Sofia, S.
Bibcode: 1994svsp.coll..280F
Altcode: 1994IAUCo.143P.280F
No abstract at ADS
Title: Three-dimensional thermoluminescence spectra of feldspars
Authors: Prescott, J. R.; Fox, P. J.
Bibcode: 1993JPhD...26.2245P
Altcode:
No abstract at ADS
Title: A Formulation of Convection for Stellar Structure
and Evolution Calculations without the Mixing-Length Theory
Approximations. II. Application to alpha Centauri A and B
Authors: Lydon, Thomas J.; Fox, Peter A.; Sofia, Sabatino
Bibcode: 1993ApJ...413..390L
Altcode:
We have constructed a series of models of Alpha Centauri A and Alpha
Centauri B for the purposes of testing the effects of convection
modeling both by means of the mixing-length theory (MLT), and by means
of parameterization of energy fluxes based upon numerical simulations
of turbulent compressible convection. We demonstrate that while MLT,
through its adjustable parameter alpha, can be used to match any
given values of luminosities and radii, our treatment of convection,
which lacks any adjustable parameters, makes specific predictions
of stellar radii. Since the predicted radii of the Alpha Centauri
system fall within the errors of the observed radii, our treatment
of convection is applicable to other stars in the H-R diagram in
addition to the sun. A second set of models is constructed using MLT,
adjusting alpha to yield not the 'measured' radii but, instead, the
radii predictions of our revised treatment of convection. We conclude
by assessing the appropriateness of using a single value of alpha to
model a wide variety of stars.
Title: Improved Solar Models Constructed with a Formulation of
Convection for Stellar Structure and Evolution Calculations without
the Mixing-Length Theory Approximations
Authors: Lydon, Thomas J.; Fox, Peter A.; Sofia, Sabatino
Bibcode: 1993ApJ...403L..79L
Altcode:
We have updated a previous attempt to incorporate within a solar
model a treatment of convection based upon numerical simulations of
convection rather than mixing-length theory (MLT). We have modified our
formulation of convection for a better treatment of the kinetic energy
flux. Our solar model has been updated to include a complete range of
OPAL opacities, the Debye-Hueckel correction to the equation of state,
helium diffusion due to gravitational settling, and atmospheres by
Kurucz. We construct a series of models using both MLT and our revised
formulation of convection and the compared results to measurements of
the solar radius, the solar luminosity, and the depth of the solar
convection zone as inferred from helioseismology. We find X(solar)
= 0.702 +/- 0.005, Y(solar) = 0.278 +/- 0.005, and Z(solar) = 0.0193
+/- 0.0005.
Title: Simulating the interaction of convection with magnetic fields
in the sun.
Authors: Fox, P. A.; Theobald, M. L.; Sofia, S.
Bibcode: 1993spd..conf...83F
Altcode:
No abstract at ADS
Title: A Formulation of Convection for Stellar Structure
and Evolution Calculations without the Mixing-Length Theory
Approximations. I. Application to the Sun
Authors: Lydon, Thomas J.; Fox, Peter A.; Sofia, Sabatino
Bibcode: 1992ApJ...397..701L
Altcode:
The problem of treating convective energy transport without MLT
approximations is approached here by formulating the results of
numerical simulations of convection in terms of energy fluxes. This
revised treatment of convective transport can be easily incorporated
within existing stellar structure codes. As an example, the technique is
applied to the sun. The treatment does not include any free parameters,
making the models extremely sensitive to the accuracy of the treatments
of opacities, chemical abundances, treatments of the solar atmosphere,
and the equation of state.
Title: Stellar Photospheric Convection, and the Effect on Spectral
Line Asymmetry
Authors: Kim, Y. -C.; Demarque, P.; Fox, P. A.
Bibcode: 1992AAS...181.3605K
Altcode: 1992BAAS...24.1175K
No abstract at ADS
Title: Alpha Centauri: A Stringent Test of Any Formulation of
Convection not Based Upon Mixing-Length Theory
Authors: Lydon, T. J.; Sofia, S.; Fox, P. A.
Bibcode: 1992AAS...181.5103L
Altcode: 1992BAAS...24R1205L
No abstract at ADS
Title: Numerical Simulations of the Surface Energy Balance of
Sunspot-Like Objects
Authors: Fox, P.; Sofia, S.; Chan, K.
Bibcode: 1992sers.conf..136F
Altcode:
No abstract at ADS
Title: A Numerical Method for Solving Systems of Linear Ordinary
Differential Equations with Rapidly Oscillating Solutions
Authors: Bernstein, Ira B.; Brookshaw, Leigh; Fox, Peter A.
Bibcode: 1992JCoPh..98..269B
Altcode:
A numerical method is presented which allows the accurate and efficient
solution of systems of linear equations of the form dzi(
x)/ dx = Σj = 1 N1Aij(
x) zj( x), i= 1, 2, …, N, when the solutions vary rapidly
compared with the Aij( x). The method consists of numerically
developing a set of basis solutions characterized by new dependent
variables which are slowly varying. These solutions can be accurately
computed with an overhead that is substantially independent of the
smallness of the scale length characterizing the solutions. Examples
are given.
Title: Stellar Photospheric Convection
Authors: Kim, Y. -C.; Fox, P. A.
Bibcode: 1992ASPC...26..172K
Altcode: 1992csss....7..172K
No abstract at ADS
Title: Constralnts on Solar Activity from Empirical and Global
Modelling
Authors: Sofia, Sabatino; Fox, Peter A.
Bibcode: 1992ASPC...27..417S
Altcode: 1992socy.work..417S
No abstract at ADS
Title: Compressible Magnetic Convection: Formulation and
Two-dimensional Models
Authors: Fox, Peter A.; Theobald, Michael L.; Sofia, Sabatino
Bibcode: 1991ApJ...383..860F
Altcode:
Details on a formulation and numerical solution of the equations of
time-dependent magnetized convection are presented. Results on the
transition between weak and strong magnetic fields where the highly
nonlinear behavior commences are discussed, and the sensitivity
of these results to the value of the magnetic resistivity, which
can significantly influence the details of the interactions, is
indicated. Consideration is given to the consequences of the findings
for modeling stellar and solar magnetic fields.
Title: An Investigation of the Sources of Solar Variability:
Preliminary Work
Authors: Cersosimo, S.; Sofia, S.; Fox, P.
Bibcode: 1991BAAS...23Q1389C
Altcode:
No abstract at ADS
Title: Convective Flows around Sunspot-Like Objects
Authors: Fox, Peter A.; Sofia, Sabatino; Chan, Kwing L.
Bibcode: 1991SoPh..135...15F
Altcode:
Results are given for calculations of convective flows around objects
in the outer layers of the Sun that have similar characteristics to
small sunspots. These objects are allowed to radiatively (diffusively)
exchange heat with their surroundings, but convective motions and
exchange are absent. This assumption is based on the simple presumption
that a sunspot magnetic field maintains pressure equilibrium with the
surrounding medium and prevents convective exchange with that medium.
Title: Convective Flows around Sunspot-Like Objects
Authors: Fox, P. A.; Sofia, S.; Chan, K. L.
Bibcode: 1991BAAS...23.1048F
Altcode:
No abstract at ADS
Title: Dynamo-Based Scheme for Forecasting the Magnitude of Solar
Activity Cycles
Authors: Layden, A. C.; Fox, P. A.; Howard, J. M.; Sarajedini, A.;
Schatten, K. H.; Sofia, S.
Bibcode: 1991SoPh..132....1L
Altcode:
In this paper we present a general framework for forecasting the
smoothed maximum level of solar activity in a given cycle, based on
a simple understanding of the solar dynamo. This type of forecasting
requires knowledge of the Sun's polar magnetic field strength at
the preceeding activity minimum. Because direct measurements of this
quantity are difficult to obtain, we evaluate the quality of a number
of proxy indicators already used by other authors which are physically
related to the Sun's polar field. We subject these indicators to a
rigorous statistical analysis, and specify in detail the analysis
technique for each indicator in order to simplify and systematize
reanalysis for future use. We find that several of these proxies
are in fact poorly correlated or uncorrelated with solar activity,
and thus are of little value for predicting activity maxima.
Title: A Sub-Grid-Scale Magnetic Resistivity Formulation
Authors: Theobald, M. L.; Fox, P.; Sofia, S.
Bibcode: 1991BAAS...23.1049T
Altcode:
No abstract at ADS
Title: Evolution of Largescale and Smallscale Magnetic Fields in
the Sun
Authors: Fox, Peter A.; Theobald, Michael L.; Sofia, Sabatino
Bibcode: 1991LNP...380..218F
Altcode: 1991IAUCo.130..218F; 1991sacs.coll..218F
This paper will discuss issues relating to the detailed numerical
simulation of solar magnetic fields, those on the small scale which
are directly observable on the surface, and those on larger scales
whose properties must be deduced indirectly from phenomena such as the
sunspot cycle. Results of simulations using the ADISM technique will
be presented to demonstrate the importance of the treatment of Alfvén
waves, the boundary conditions, and the statistical evolution of small
scale convection with magnetic fields. To study the large scale fields
and their time dependence, the magnetic resistivity plays an important
role; its use will be discussed in the paper.
Title: Global models of intermediate timescale variability on the Sun.
Authors: Fox, Peter A.
Bibcode: 1990NASCP3086...27F
Altcode: 1990cisv.nasa...27F
In recent years a number of advances in both observation and theory
have increased our understanding of the solar interior and how to model
it. For climate studies, the timescale of interest for changes in the
Sun ranges from decades to centuries. This paper attempts to highlight
some of the theoretical advances that will contribute to the building
of global models of the Sun's variability on intermediate timescales
and describe what the current constraints on the important components
are. Finally a short discussion presenting some implications for input
to climate modeling will be presented.
Title: Magnetic Interaction with Compressible Convection
Authors: Theobald, M. L.; Fox, P. A.; Sofia, S.
Bibcode: 1990BAAS...22Q.879T
Altcode:
No abstract at ADS
Title: On the Theoretical Distribution of Solar Granulation and
Solar Mesogranulation
Authors: Fox, P. A.; Sofia, S.; Chan, K. L.
Bibcode: 1990BAAS...22..879F
Altcode:
No abstract at ADS
Title: How Much Can Theoretical Models of Compressible Convection
Tell Us about Solar Granulation?
Authors: Fox, P. A.
Bibcode: 1989ASIC..263..401F
Altcode: 1989ssg..conf..401F
No abstract at ADS
Title: Interaction of Solar Granulation with Weak and Strong
Magnetic Fields
Authors: Fox, P. A.
Bibcode: 1989ASIC..263..555F
Altcode: 1989ssg..conf..555F
No abstract at ADS
Title: The axial summit graben and cross-sectional shape of the
East Pacific Rise as indicators of axial magma chambers and recent
volcanic eruptions
Authors: Macdonald, Ken C.; Fox, P. J.
Bibcode: 1988E&PSL..88..119M
Altcode:
The axis of the East Pacific Rise (EPR) undulates up and down hundreds
of meters over distances of 30-200 km along strike, the deep areas
occurring at transform faults and other ridge axis discontinuities
such as overlapping spreading centers (OSCs). We have suggested that
systematic variations in depth and cross-sectional shape of the rise
are indicators of the changes in the local axial magmatic budget along a
given ridge segment [1]. A comparison of recently collected multichannel
seismic (MCS) data [2] with our Sea Beam and SeaMARC II data have
allowed us to test and advance this hypothesis. Along the EPR from 9°
to 13°N there is an excellent correlation between three parameters
that are all directly related to the phase of a magmatic cycle along a
given ridge segment: the cross-sectional shape of the rise, the presence
or absence of an axial summit graben, and the presence or absence of
a shallow axial magma chamber (as interpreted from MCS data). Where
the axial magma chamber is present, the cross-sectional shape of the
ridge is broad and an axial summit graben is recognized along the
axis. In contrast, where the cross-sectional shape of the rise is
narrow and triangular, an axial magma chamber is not detected and an
axial summit graben is absent. These ridge axis characteristics tend to
occur along deeper portions of a given ridge segment, often near ridge
axis discontinuities. We suggest that these systematic variations in
ridge axis morphology (cross-sectional shape) and structure (presence
or absence of an axial graben) reflect spatial and temporal variations
in the magmatic budget of the ridge axis. Where the magmatic budget is
waxing, shallow-level magma reservoirs in the crust and underlying upper
mantle swell, creating a broad axial bulge with a summit graben. Where
the magmatic budget is diminished, the crustal magma chamber is small
(< 2 km wide) or absent and the ridge axis is characterized by a
narrow triangular edifice that lacks a clearly defined and continuous
axial graben. A summit graben is missing because the underlying axial
magma reservoir is not large enough to produce a significant collapse
structure or a caldera. This proposed correlation of shape, structure
and magmatic parameters fails along only two short portions of the
ridge. In these areas there is evidence for an axial magma chamber and
the rise has a broad cross-sectional shape, but there is no summit
graben. Bottom photographs and submersible results, however, show
that in these areas the rise crest is covered with very fresh lavas
undisrupted by faulting, suggesting that the summit graben has been
recently filled in by lava flows, and the development of a summit graben
(or a linear caldera) by volcano-tectonic collapse has not yet occurred.
Title: Large Scale Solar and Stellar Magnetic Fields
Authors: Fox, Peter A.
Bibcode: 1987LNP...291...57F
Altcode: 1987csss....5...57F
With the recent advent of stellar evolution calculations that include
the effect of rotation, the prospect of correctly evaluating the
influence of magnetic fields in a wide class of stars has been greatly
improved. Calculations of large scale (global) magnetic fields will
be presented that utilize sequences of models of a rotating star
(the Sun) that take into account differential rotation and meridional
circulation. The influence of various magnetic field configurations
and strengths will be considered as well as the possible effect of
the Lorentz force on the equations of motion.
Title: The Generation of Magnetic Fields in the Sun
Authors: Fox, Peter A.; Bernstein, Ira B.
Bibcode: 1987ASSL..137..213F
Altcode: 1987isav.symp..213F
In this paper results of a preliminary investigation into the existence
of large scale magnetic fields in the sun are given. Using a kinematic
model with prescribed internal rotation and a standard solar model,
the poloidal and toroidal components of the magnetic field are
calculated. The basic decay time is of the order of the age of the
sun. In addition the fields are quite sensitive to slight variations
in the internal rotation. The boundary condition at the solar surface
also does not seem to influence the inner regions where large scale
fields seem possible.
Title: Geological and geophysical investigation of the Mid-Cayman
Spreading Centre: seismic velocity measurements and implications
for the constitution of layer 3
Authors: Karson, J. A.; Fox, P. J.
Bibcode: 1986GeoJ...85..389K
Altcode: 1986GeoJI..85..389K
No abstract at ADS
Title: The influence of magnetic fields on convective motions in
the outer layers of the sun
Authors: van der Borght, R.; Fox, P.
Bibcode: 1985AuJPh..38..845V
Altcode:
In this paper the authors make a preliminary investigation of the
nonlinear equations of compressible convection under the influence of
solar-type magnetic fields. A polytropic model of the basic structure
is used and, although the model is somewhat restrictive, good agreement
is obtained with general observations in both strong and weak field
cases. The value and influence of the turbulent magnetic resistivity
is investigated and the depth dependence of the vertical velocity
within a given period is used to study the way in which the overstable
oscillations change their direction of flow from positive to negative.
Title: Solar granulation - The influence of viscosity laws on
theoretical models
Authors: Fox, P.; van der Borght, R.
Bibcode: 1985PASA....6...60F
Altcode: 1985PASAu...6...60F
Numerical simulations of solar granulation are presented. Emphasis is
given to the influence of various viscosity laws on predictions of the
velocity field, the degree of overshooting into upper stable layers,
and the degree of sensitivity to overall changes in viscosity. The depth
dependence of the Prandtl number in a solar granulation model having
a constant dynamic viscosity of 0.005, is illustrated in graphic form.
Title: Convective Motions as an Indicator of Solar Structure
Authors: van der Borght, R.; Fox, P.
Bibcode: 1984IAUS..105...71V
Altcode:
The fully compressible single mode equations which take into account the
variation with depth of the degree of ionization, thermal diffusivity,
eddy kinematic viscosity and buoyancy have been derived. With such
equations the characteristics of a particular model can be fully
taken into account and the resultant thermal convection can be studied
in detail. Trial integrations have been carried out and the results
confirm earlier results based on the polytropic approximation (Van
der Borght and Fox 1983) and show how sensitive the results are to
the value adopted for the Prandtl number.
Title: A multimode investigation of granular and supergranular
motions. I. Boussinesq model.
Authors: van der Borght, R.; Fox, P.
Bibcode: 1984bbgl.symp..269V
Altcode:
The two types of large-scale convective motion in the sun, granulation
and supergranulation, were studied theoretically based on a multi-mode
expansion of the Boussinesq approximation. The basic hydrodynamic
equations governing the convective motions are derived, assuming the
Rayleigh number is variable with depth and is in excess of its linear
value in the top 10 percent of the convective layer. Estimates of eddy
conductivity, Prandtl number, and buoyancy in the convective layer are
compared with observations and the results are discussed. Expansion
of the theoretical calculations to a fully compressible model which
takes into account the depth dependence of the parameters is briefly
discussed.
Title: Solar Granulation
Authors: van der Borght, R.; Fox, P. A.
Bibcode: 1984aprm.conf..483V
Altcode:
The present model of solar granulation, in which the parameters vary
across the layer, is based on the anelastic approximation and assumes
that the convection does not alter appreciably the mean density and
temperature distributions in the layer.
Title: Granulation and supergranulation as a diagnostic test of
solar structure
Authors: van der Borght, R.; Fox, P.
Bibcode: 1983PASA....5..168V
Altcode: 1983PASAu...5..168V
Current knowledge of solar structure is applied to the evaluation
of theoretical models of convective energy transport in stellar or
solar regions with superadiabatic temperature gradients. Techniques
are developed to test the accuracy of mixing-length models and
their nonlocal extensions on the basis of observational data
on supergranulation and granulation in the outer layers of the
sun. Supergranulation is found to play only a minor role in energy
transport. It is predicted that the smaller upper-layer temperature
gradients of nonlocal theories can strongly influence granule flux
modulation.
Title: Accuracy of the anelastic approximation in the theory of
compressible convection
Authors: van der Borght, R.; Fox, P.
Bibcode: 1983PASA....5..170V
Altcode: 1983PASAu...5..170V
The use of the anelastic approximation (AA) in astrophysical atmosphere
models is examined critically in numerical experiments, considering
the case of convective motion in the outer layers of the sun. The full
nonlinear equations of convective motions in a compressible medium
with polytropic structure of Van der Borght (1977) are integrated
numerically, and the results are compared with those obtained with
the AA (for the same boundary conditions and parameter values) in
graphs. Significant discrepancies are noted, especially at the top
of the convective layer and in the parameters vertical velocity,
horizontal velocity, temperature fluctuation, and density fluctuation.
Title: A convective model of solar granulation
Authors: van der Borght, R.; Fox, P.
Bibcode: 1983PASA....5..166V
Altcode: 1983PASAu...5..166V
A convective numerical model of solar granulation is developed. The full
nonlinear equations of finite-amplitude convection in a compressive
medium with polytropic structure derived by Van der Borght (1977) in
the one-mode approximation are integrated numerically for specific
boundary conditions. The results are presented in a table listing
upper-boundary velocity, flux modulation, the percentage of total flux
carried by granules, and the e-folding time for Prandtl numbers 0.2,
0.24, and 0.5. The best fit to observations is obtained at Prandtl
number 0.2, where the table parameters are 0.97 km/sec, 16.37 percent,
4.2 percent, and 6.0 min, respectively.
Title: Magnetic properties of dredged oceanic gabbros and the source
of marine magnetic anomalies
Authors: Kent, D. V.; Honnorez, B. M.; Opdyke, N. D.; Fox, P. J.
Bibcode: 1978GeoJ...55..513K
Altcode: 1978GeoJI..55..513K
No abstract at ADS
Title: Solar Atmospheric Model Including OH-Continuum Opacity
Authors: Fox, P. W.; Tarafdar, S. P.
Bibcode: 1978SoPh...60..241F
Altcode:
Flux-constant model has been constructed for solar atmosphere,
including OH-bound-free opacity, but without any line opacity, atomic,
ionic or molecular. A comparison between the theoretical and observed
intensity and flux shows that OH-opacity can account for the missing
solar opacity, except at those wavelengths where the intensity shows the
presence of numerous absorption lines, provided the unknown oscillator
strength of the transition is 0.3. The T − τ relation, however
gives larger temperatures at smaller depths than those by the empirical
model. This and the large theoretical flux in the spectral region with
heavy line absorption indicate the importance of line opacity.
Title: Comparison of TDI-fluxes with those from model-atmosphere
including OH-opacity.
Authors: Tarafdar, S. P.; Fox, P. W.
Bibcode: 1978A&A....67..281T
Altcode:
Model atmospheres have been constructed including OH bound-free
opacity for temperatures corresponding to F stars. The emergent fluxes
from the models have been compared with their values observed from
the TD1 satellite. It has been found that OH bound-free opacity is
not very important for F0 V stars but starts contributing from F2 V
with increasing importance towards later spectral types. Comparison
of theoretical fluxes with their observed values shows that OH
bound-free opacity can account for the missing UV opacity in F stars
for wavelengths where the observed flux does not indicate the presence
of many lines and alleviates the discrepancy in other parts of the
spectral region.
Title: Particle motion on Mars inferred from the Viking lander cameras
Authors: Sagan, C.; Pieri, D.; Fox, P.; Arvidson, R. E.; Guinness,
E. A.
Bibcode: 1977JGR....82.4430S
Altcode:
The cameras of the Viking landers have uncovered several lines of
evidence for fine particle mobility on the Martian surface, including
particulate drifts, rock-associated raised streaks, and probable
ventifacts. Inferred peak wind directions in both Chryse and Utopia
are roughly the same and are consistent with peak winds inferred by
orbiter photography. A 24° systematic offset between the direction
of rock-associated streaks in the Viking 1 landing site and Mariner
9 and Viking observations of crater-associated streaks is consistent
in both sign and magnitude with a Coriolis acceleration of particles
entrained by high-velocity winds in the course of the production of
crater-associated streaks. If a significant fraction of the impact
energy upon collision goes into deformation, strain, and rupture,
there should be a preferential destruction of the most easily saltated
grains, which are here called kamikaze particles, and a depletion of
150-μm-diameter grains. Observations of fine particulates dumped on
the VL-1 grid indicate that major saltation events occurred between
sols 96 and 207 and were caused by winds of >50 m s-1,
normalized to the top of the velocity boundary layer. This is the first
observation of saltation on another planet and a rough confirmation
of the usual Bagnold saltation theory applied to another planet.
Title: Particle Motion on Mars Inferred from the Viking Lander
Cameras.
Authors: Sagan, C.; Pieri, D.; Fox, P.; Arvidson, R. E.; Guinness,
E. A.
Bibcode: 1977BAAS....9..538S
Altcode:
No abstract at ADS
Title: The Surface of Mars: The View from the Viking 2 Lander
Authors: Mutch, T. A.; Grenander, S. U.; Jones, K. L.; Patterson,
W.; Arvidson, R. E.; Guinness, E. A.; Avrin, P.; Carlston, C. E.;
Binder, A. B.; Sagan, C.; Dunham, E. W.; Fox, P. L.; Pieri, D. C.;
Huck, F. O.; Rowland, C. W.; Taylor, G. R.; Wall, S. D.; Kahn, R.;
Levinthal, E. C.; Liebes, S., Jr.; Tucker, R. B.; Morris, E. C.;
Pollack, J. B.; Saunders, R. S.; Wolf, M. R.
Bibcode: 1976Sci...194.1277M
Altcode:
Viking 2 lander began imaging the surface of Mars at Utopia Planitia
on 3 September 1976. The surface is a boulder-strewn reddish desert
cut by troughs that probably form a polygonal network. A plateau can
be seen to the east of the spacecraft, which for the most probable
lander location is approximately the direction of a tongue of ejecta
from the crater Mie. Boulders at the lander 2 site are generally more
vesicular than those near lander 1. Fines at both lander sites appear to
be very fine-grained and to be bound in a duricrust. The pinkish color
of the sky, similar to that observed at the lander 1 site, indicates
suspension of surface material. However, the atmospheric optical depth
is less than that at the lander 1 site. After dissipation of a cloud
of dust stirred during landing, no changes other than those stemming
from sampling activities have been detected in the landscape. No signs
of large organisms are apparent at either landing site.
Title: The Canals of Mars: An Assessment after Mariner 9
Authors: Sagan, C.; Fox, P.
Bibcode: 1975Icar...25..602S
Altcode:
The Lowellian canal network has been compared with the results of
Mariner 9 photography of Mars. A small number of canals may correspond
to rift valleys, ridge systems, crater chains, and linear surface
albedo markings. But the vast bulk of classical canals correspond
neither to topographic nor to albedo features, and appear to have no
relation to the real Martian surface.
Title: Fractionation of abyssal tholeiites: samples from the
Oceanographer Fracture Zone (35°N, 35°W)
Authors: Shibata, T.; Fox, P. J.
Bibcode: 1975E&PSL..27...62S
Altcode:
Chemical analyses of 48 fresh abyssal tholeiite specimens sampled from
two dredge localities clearly define systematic chemical differences
which indicate a moderate iron-enrichment trend of fractionation
oblique to the FeO 2O, P 2O 5 and
TiO 2. These results suggest that fractionation may be
important in controlling the chemistry of abyssal tholeiites along
sections of the mid-oceanic ridge.
Title: Mariner 9 photometry of the polar of Mars: preliminary results.
Authors: Wood, A. T.; Veverka, J.; Fox, P.
Bibcode: 1974BAAS....6..487W
Altcode:
No abstract at ADS
Title: Veränderliche Erscheinungen der Marsoberfläche: Vorläufige
Mariner 9-Televisions-Ergebnisse. I.
Authors: Sagan, C.; Veverka, J.; Fox, P.; Dubisch, R.; Lederberg,
J.; Levinthal, E.; Quam, L.; Tucker, R.; Pollack, J. B.; Smith, B. A.
Bibcode: 1974Stern..50..139S
Altcode:
No abstract at ADS
Title: Veränderliche Erscheinungen der Marsoberfläche: Vorläufige
Mariner 9-Televisions-Ergebnisse. II.
Authors: Sagan, C.; Veverka, J.; Fox, P.; Dubisch, R.; Lederberg,
J.; Levinthal, E.; Quam, L.; Tucker, R.; Pollack, J. B.; Smith, B. A.
Bibcode: 1974Stern..50..193S
Altcode:
No abstract at ADS
Title: Variable Features on Mars: Mariner 9 Global Results
Authors: Sagan, C.; Veverka, J.; Fox, P.; French, R.; Dubisch, R.;
Gierasch, P.; Quam, L.; Lederberg, J.; Levinthal, E.; Tucker, R.;
Eross, B.; Pollack, J.
Bibcode: 1973BAAS....5R.295S
Altcode:
No abstract at ADS
Title: Variable Features on Mars: Mariner 9 Observations of Promethei
Sinus
Authors: Sagan, C.; Veverka, J.; Fox, P.; French, R.; Dubisch, R.;
Gierasch, P.; Quam, L.; Lederberg, J.; Levinthal, E.; Tucker, R.;
Eross, B.; Pollack, J.
Bibcode: 1973BAAS....5S.295S
Altcode:
No abstract at ADS
Title: Variable Features on Mars, 2, Mariner 9 Global Results
Authors: Sagan, C.; Veverka, J.; Fox, P.; Dubisch, R.; French, R.;
Gierasch, P.; Quam, L.; Lederberg, J.; Levinthal, E.; Tucker, R.;
Eross, B.; Pollack, J. B.
Bibcode: 1973JGR....78.4163S
Altcode:
Systematic Mariner 9 monitoring of the space and time distribution of
Martian bright and dark markings, the streaks and splotches, indicates a
range of global correlations. The time variable classical dark markings
owe their configurations and variability to their constituent streaks
and splotches, produced by windblown dust. Streaks and splotches are
consistent wind direction indicators. Correlation of global streak
patterns with general circulation models shows that velocities ∼50
to 90 m/sec above the boundary layer are necessary to initiate grain
motion on the surface and to produce streaks and splotches. Detailed
examples of changes in Syrtis Major, Lunae Palus, and Promethei
Sinus are generally consistent with removal of bright sand and dust
and uncovering of darker underlying material as the active agent in
such changes, although dark mobile material probably also exists on
Mars. The generation of streaks and the progressive albedo changes
observed require only threshold velocities of about 2 m/sec for about
1 day at the grain surface. We propose that the dark collar observed
following the north polar cap in its retreat is produced by the scouring
of bright overlying dust from the polar peripheral ground by winds
driven by the temperature differences between frosted and unfrosted
terrain. The stability of bright streaks and the variability of dark
streaks and splotches, as well as their contrast, can be the result
of size differences of the constituent particles.
Title: Variable Features on Mars: Preliminary Mariner 9 Television
Results.
Authors: Sagan, C.; Veverka, J.; Fox, P.; Dubisch, R.; Lederberg,
J.; Levinthal, E.; Quam, L.; Tucker, R.; Pollack, J.; Smith, B.
Bibcode: 1972BAAS....4..313S
Altcode:
No abstract at ADS
Title: Stellar parallaxes - Determined from photographs made with
the 181/2 inch refractor of the Dearborn Observatory.
Authors: Fox, P.; Anger, C. J.; Bannister, R. D.; Bennot, M.;
Gushee, V. M.; Hill, L. E.; Sayer, L. E.; Sheldon, E.; Tibbles, R. M.;
Whitaker, H.; Young, J. M.; Brown, F. L.; Comrie, L. J.; Crump, C. C.;
Curtis, H. B.; Dickson, J. B.; Gingrich, C. H.; Hoff, A. H.; Horn,
E. F.; Johnson, W. E.; Kim, H. Y.; Paddock, G. F.; Stetson, H. T.;
Wilson, D. T.; Wylie, L. R.
Bibcode: 1935AnDea...3D...7F
Altcode:
No abstract at ADS
Title: Measures of radial velocity of alpha Coronae Borealis.
Authors: Fox, P.
Bibcode: 1929ApJ....69...72F
Altcode:
No abstract at ADS
Title: Orbit of the spectroscopic binary of 13 Ceti.
Authors: FOX, P.
Bibcode: 1908ApJ....27..372F
Altcode:
No abstract at ADS
Title: Une Grande Protubérance Éruptive
Authors: Fox, P.
Bibcode: 1907BSBA...12A.345F
Altcode:
No abstract at ADS