Superthermal Electron Deposition on the Mars Nightside During ICMEs

Journal Article · 09 October 2020 · Journal of Geophysical Research. Space Physics

DOI: https://doi.org/10.1029/2020ja028430 · OSTI ID:1815384

Xu, Shaosui  ^[1]; Curry, Shannon M.  ^[1]; Mitchell, David L.  ^[1]; Luhmann, Janet G.  ^[1]; Lillis, Robert J.  ^[1]; Dong, Chuanfei  ^[2]

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1. Univ. of California, Berkeley, CA (United States). Space Sciences Lab.
2. Department of Astrophysical Sciences and Princeton Plasma Physics Laboratory Princeton University Princeton NJ USA

Superthermal electron precipitation is one of the main sources supporting the Mars nightside ionosphere. It is expected that solar wind electron fluxes are to increase significantly during interplanetary coronal mass ejections (ICMEs) and therefore an enhanced nightside ionospheric density. This study is to quantify the variation of the precipitating and deposited electron fluxes during five extreme ICMEs encountered by Mars Global Surveyor (MGS). We find that energy fluxes correlate better with the upstream dynamic pressure proxy than number fluxes and electron fluxes increase more at high energies, which means that electrons tend to have a lower peak production altitude during storm times. The precipitating and net/deposited fluxes are increased up to an order of magnitude from low to high dynamic pressures. The estimated total electron content (TEC) is a few times of 10¹⁴ m^-2 for quiet times and on the order of 1015 m^-2 for storm times, with an enhancement up to an order of magnitude locally near strong crustal fields. Crustal magnetic fields have an effect on the deposited fluxes with more prominent magnetic reflection over strong magnetic fields during quiet periods, which is significantly reduced during storm times. Lastly, we estimate a global energy input from downward fluxes of 1.1 × 10⁸ and 5.5 × 10⁸ W and the globally deposited energy from net fluxes of 2.0 × 10⁷ and 1.6 × 10⁸ W for quiet and storm time periods, a factor of 5 and 8 enhancement globally, respectively, but up to an order of magnitude locally near strong crustal fields.

• Research Organization: Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)
• Sponsoring Organization: National Aeronautics & Space Administration (NASA); USDOE Office of Science (SC)
• Grant/Contract Number: AC02-09CH11466
• OSTI ID: 1815384
• Journal Information: Journal of Geophysical Research. Space Physics, Journal Name: Journal of Geophysical Research. Space Physics Journal Issue: 10 Vol. 125; ISSN 2169-9380
• Publisher: American Geophysical UnionCopyright Statement
• Country of Publication: United States
• Language: English