ENA; protons; ion precipitation; TWINS mission; Monte Carlo
Abstract :
[en] We formulate the first analytical model for energetic neutral atom (ENA) emissivity that partially corrects for the global viewing geometry dependence of low-altitude emissions (LAEs) observed by Two Wide-angle Imaging Neutral-atom Spectrometers (TWINS). The emissivity correction requires the pitch angle distribution (PAD) and geophysical location of low-altitude ENAs. To estimate PAD, we create an energy-dependent analytical model, based on a Monte Carlo simulation. We account for energy binning by integrating model PAD over each energy bin. We account for finite angular pixels by computing emissivity as an integral over the pitch angle range sampled by the pixel. We investigate location uncertainty in TWINS pixels by performing nine variations of the emissivity calculation. Using TWINS 2 ENA imaging data from 1131 to 1145 UT on 6 April 2010, we derive emissivity-corrected ion fluxes for two angular pixel sizes: 4° and 1°. To evaluate the method, we compare TWINS-derived ion fluxes to simultaneous in situ data from the National Oceanic and Atmospheric Administration (NOAA) 17 satellite. The TWINS-NOAA agreement for emissivity-corrected flux is improved by up to a factor of 7, compared to uncorrected flux. The highest 1° pixel fluxes are a factor of 2 higher than for 4° pixels, consistent with pixel-derived fluxes that are artificially low because subpixel structures are smoothed out, and indicating a possible slight advantage to oversampling the instrument-measured LAE signal. Both TWINS and NOAA ion fluxes decrease westward of 2000 magnetic local time. The TWINS-NOAA comparison indicates that the global ion precipitation oval comprises multiple smaller-scale (3-5° of latitude) structures.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Goldstein, J.
Bisikalo, D.V.; INASAN
Shematovich, V.I.
Gérard, Jean-Claude ; Université de Liège > Département d'astrophys., géophysique et océanographie (AGO) > Département d'astrophys., géophysique et océanographie (AGO)
Søraas, F.
McComas, D.J.
Valek, P.W.
LLera, K.
Redfern, J. J.
Language :
English
Title :
Analytical estimate for low-altitude ENA emissivity
Publication date :
February 2016
Journal title :
Journal of Geophysical Research. Space Physics
ISSN :
2169-9380
eISSN :
2169-9402
Publisher :
Wiley, Hoboken, United States
Volume :
121
Issue :
2
Pages :
1167-1191
Peer reviewed :
Peer Reviewed verified by ORBi
Name of the research project :
CODYMAV; PRODEX - PROgramme de Développement d'Expériences scientifiques
Bai, C., R. Conwell, H. Babla, and, J. Kindem, (2011), Improving image resolution using oversampling for pixelated solid-state Gamma cameras, J. Nucl. Med., 52, 489.
Basu, B., J. R. Jasperse, R. M. Robinson, R. R. Vondrak, and, D. S. Evans, (1987), Linear transport theory of auroral proton precipitation: A comparison with observations, J. Geophys. Res., 92, 5920-5932, doi: 10.1029/JA092iA06p05920.
Bazell, D., E. Roelof, T. Sotirelis, P. Brandt, H. Nair, P. Valek, J. Goldstein, and, D. McComas, (2010), Comparison of TWINS images of low-altitude emission (LAE) of energetic neutral atoms with DMSP precipitating ion fluxes, J. Geophys. Res., 115, A10204, doi: 10.1029/2010JA015644.
Brandt, P. C., S. Barabash, E. C. Roelof, and, C. J. Chase, (2001a), Energetic neutral atom imaging at low altitudes from the Swedish microsatellite Astrid: Observations at low (≤10 keV) energies, J. Geophys. Res., 106, 24,663-24,674, doi: 10.1029/2000JA900119.
Brandt, P. C., S. Barabash, E. C. Roelof, and, C. J. Chase, (2001b), Energetic neutral atom imaging at low altitudes from the Swedish microsatellite Astrid: Extraction of the equatorial ion distribution, J. Geophys. Res., 106 (A11), 25,731-25,744.
Brandt, P. C., D. G. Mitchell, E. C. Roelof, S. M. Krimigis, C. P. Paranicas, B. H. Mauk, J. Saur, and, R. DeMajistre, (2005), ENA imaging: Seeing the invisible, Johns Hopkins APL Tech. Dig., 26 (2), 143-155.
Buzulukova, N., M.-C. Fok, E. C. Roelof, J. Redfern, J. Goldstein, P. Valek, and, D. J. McComas, (2013), Comparative analysis of low-altitude ENA emissions in two substorms, J. Geophys. Res. Space Physics, 118, 724-731, doi: 10.1002/jgra.50103.
Frey, H. U., S. B. Mende, S. A. Fuselier, T. J. Immel, and, N. Østgaard, (2003), Proton Aurora in the Cusp During Southward IMF, vol. 108, 1277.
Fruchter, A. S., and, R. N. Hook, (2002), Drizzle: A method for the linear reconstruction of undersampled images, Publ. Astron. Soc. Pac., 114, 144-152, doi: 10.1086/338393.
Galand, M., and, A. D. Richmond, (1999), Magnetic mirroring in an incident proton beam, J. Geophys. Res., 104, 4447-4455, doi: 10.1029/1998JA900123.
Galand, M., J. Lilensten, W. Kofman, and, D. Lummerzheim, (1998), Proton transport model in the ionosphere: 2. Influence of magnetic mirroring and collisions on the angular redistribution in a proton beam, Ann. Geophys., 16, 1308-1321, doi: 10.1007/s00585-998-1308-y.
Gérard, J.-C., B. Hubert, D. V. Bisikalo, and, V. I. Shematovich, (2000), A model of the Lyman-α line profile in the proton aurora, J. Geophys. Res., 105, 15795, doi: 10.1029/1999JA002002.
Gérard, J.-C., B. Hubert, M. Meurant, V. I. Shematovich, D. V. Bisikalo, H. Frey, S. Mende, G. R. Gladstone, and, C. W. Carlson, (2001), Observation of the proton aurora with IMAGE FUV imager and simultaneous ion flux in situ measurements, J. Geophys. Res., 106, 28,939-28,948, doi: 10.1029/2001JA900119.
Goldstein, J., and, D. J. McComas, (2013), Five years of stereo magnetospheric imaging by TWINS, Space Sci. Rev., 180, 39-70, doi: 10.1007/s11214-013-0012-8.
Goldstein, J., P. Valek, D. J. McComas, J. Redfern, and, F. Soraas, (2013), Local-time dependent low-altitude ion spectra deduced from TWINS ENA images, J. Geophys. Res. Space Physics, 118, 2928-2950, doi: 10.1002/jgra.50222.
Hardy, D. A., M. S. Gussenhoven, and, D. Brautigam, (1989), A statistical model of auroral ion precipitation, J. Geophys. Res., 94, 370-392, doi: 10.1029/JA094iA01p00370.
Hedin, A. E., (1987), MSIS-86 thermospheric model, J. Geophys. Res., 92, 4649-4662, doi: 10.1029/JA092iA05p04649.
Hedin, A. E., (1991), Extension of the MSIS thermospheric model into the middle and lower atmosphere, J. Geophys. Res., 96, 1159-1172.
Hubert, B., J.-C. Gérard, D. V. Bisikalo, V. I. Shematovich, and, S. C. Solomon, (2001), The role of proton precipitation in the excitation of auroral FUV emissions, J. Geophys. Res., 106, 21,475-21,494, doi: 10.1029/2000JA000288.
LLera, K., J. Goldstein, D. McComas, and, P. Valek, (2014), Energy spectral evolution of precipitating ring current ions using TWINS low-altitude emissions (LAEs) and in-situ NOAA observations, Abstract SM31D-4222 presented at 2014 Fall Meeting, AGU, San Francisco, Calif.
McComas, D. J., et al., (2009), The Two Wide-angle Imaging Neutral-atom Spectrometers (TWINS) NASA mission-of-opportunity, Space Sci. Rev., 142, 157-231, doi: 10.1007/s11214-008-9467-4.
McComas, D. J., N. Buzulukova, M. G. Connors, M. A. Dayeh, J. Goldstein, H. O. Funsten, S. Fuselier, N. A. Schwadron, and, P. Valek, (2012), Two Wide-Angle Imaging Neutral-Atom Spectrometers and Interstellar Boundary Explorer energetic neutral atom imaging of the 5 April 2010 substorm, J. Geophys. Res., 117, A03225, doi: 10.1029/2011JA017273.
Mitchell, D. G., P. C. Brandt, E. C. Roelof, D. C. Hamilton, K. C. Retterer, and, S. Mende, (2003), Global imaging of O+ from IMAGE/HENA, Space Sci. Rev., 109, 63-75, doi: 10.1023/B:SPAC.0000007513.55076.00.
Newell, P. T., T. Sotirelis, and, S. Wing, (2010), Seasonal variations in diffuse, monoenergetic, and broadband aurora, J. Geophys. Res., 115, A03216, doi: 10.1029/2009JA014805.
Pollock, C., et al., (2001), First medium energy neutral atom MENA images of Earth's magnetosphere during substorm and storm-time, Geophys. Res. Lett., 28, 1147-1150.
Pollock, C. J., A. Isaksson, J.-M. Jahn, F. Søraas, and, M. Sørbø, (2009), Remote global-scale observations of intense low-altitude ENA emissions during the Halloween geomagnetic storm of 2003, Geophys. Res. Lett., 36, L19101, doi: 10.1029/2009GL038853.1987.
Roelof, E. C., and, A. J. Skinner, (2000), Extraction of ion distributions from magnetospheric ENA and EUV images, Space Sci. Rev., 91, 437-459.
Søraas, F., and, K. Aarsnes, (1996), Observations of ENA in and near a proton arc, Geophys. Res. Lett., 23, 2959-2962, doi: 10.1029/96GL02821.
Søraas, F., and, M. Sørbø, (2013), Low altitude observations of ENA from the ring current and from the proton oval, J. Atmos. Sol. Terr. Phys., 99, 104-110, doi: 10.1016/j.jastp.2012.10.003.
Strickland, D. J., R. E. Daniell Jr., J. R. Jasperse, and, B. Basu, (1993), Transport-theoretic model for the electron-proton-hydrogen atom aurora: 2. Model results, J. Geophys. Res., 98, 21,533-21,548, doi: 10.1029/93JA01645.
Valek, P., P. C. Brandt, N. Buzulukova, M.-C. Fok, J. Goldstein, D. J. McComas, J. D. Perez, E. Roelof, and, R. Skoug, (2010), Evolution of low altitude and ring current ENA emissions from a moderate magnetospheric storm: Continuous and simultaneous TWINS observations, J. Geophys. Res., 115, A111209, doi: 10.1029/2010JA015429.
Valek, P. W., J. Goldstein, D. J. McComas, R. Iiie, N. Buzulukova, M.-C. Fok, and, J. D. Perez, (2013), Oxygen-hydrogen differentiated observations from TWINS: The 22 July 2009 storm, J. Geophys. Res. Space Physics, 118, 3377-3393, doi: 10.1002/jgra.50204.
Valek, P. W., J. Goldstein, D. J. McComas, M. Fok, and, D. G. Mitchell, (2014), Large magnetic storms as viewed by TWINS: A study of the differences in the medium energy ENA composition, J. Geophys. Res. Space Physics, 119, 2819-2835, doi: 10.1002/2014JA019782.
Valek, P. W., J. Goldstein, J.-M. Jahn, D. J. McComas, and, H. E. Spence, (2015), First joint in situ and global observations of the medium-energy oxygen and hydrogen in the inner magnetosphere, J. Geophys. Res. Space Physics, 120, 7615-7628, doi: 10.1002/2015JA021151.
