P21A-2083
Multi-fluid MHD Study of the Solar Wind Interaction with Mars' Upper Atmosphere during the 2015 March 8th ICME Event

Tuesday, 15 December 2015
Poster Hall (Moscone South)
Chuanfei Dong1, Yingjuan Ma2, Stephen W Bougher1, Gabor Toth1, Andrew F Nagy1, Jasper S Halekas3, Yaxue Dong4, Shannon Curry5, Janet G Luhmann6, Dave A Brain7, John E P Connerney8, Jared R Espley8, Paul R Mahaffy8, Mehdi Benna8, James P McFadden6, David L Mitchell6, Gina A DiBraccio9, Robert J Lillis6, Bruce Martin Jakosky10 and Joseph M Grebowsky8, (1)University of Michigan Ann Arbor, Ann Arbor, MI, United States, (2)University of California Los Angeles, Los Angeles, CA, United States, (3)University of Iowa, Physics and Astronomy, Iowa City, IA, United States, (4)University of Colorado at Boulder, Boulder, CO, United States, (5)Space Sciences Laboratory, Berkeley, CA, United States, (6)University of California Berkeley, Berkeley, CA, United States, (7)University of Colorado at Boulder, Laboratory for Atmospheric and Space Physics, Boulder, CO, United States, (8)NASA Goddard Space Flight Center, Greenbelt, MD, United States, (9)NASA Goddard Space Flight Center, Solar System Exploration Division, Greenbelt, MD, United States, (10)Laboratory for Atmospheric and Space Physics, Boulder, CO, United States
Abstract:
The 3-D Mars multi-fluid BATS-R-US MHD code is used to study the solar wind interaction with the Martian upper atmosphere during the 2015 March 8th interplanetary coronal mass ejection (ICME). We studied four steady-state cases, corresponding to three major ICME phases: pre-ICME phase (Case 1), sheath phase (Cases 2--3), and ejecta phase (Case 4). Detailed data-model comparisons demonstrate that the simulation results are in good agreement with Mars Atmosphere and Volatile EvolutioN (MAVEN) measurements, indicating that the multi-fluid MHD model can reproduce most of the features observed by MAVEN, thus providing confidence in the estimate of ion escape rates from its calculation. The total ion escape rate is increased by an order of magnitude, from 2.05×1024 s-1 (pre-ICME phase) to 2.25×1025 s-1 (ICME sheath phase), during this time period. The calculated ion escape rates were used to examine the relative importance of the two major ion loss channels from the planet: energetic pickup ion loss through the dayside plume and cold ionospheric ion loss through the nightside plasma wake region. We found that the energetic pickup ions escaping from the dayside plume could be as much as ~23% of the total ion loss prior to the ICME arrival. Interestingly, the tailward ion escape rate is significantly increased at the ejecta phase, leading to a reduction of the dayside ion escape to ~5% of the total ion loss. Under such circumstance, the cold ionospheric ions escaping from the plasma wake comprise the majority of the ion loss from the planet. Furthermore, by comparing four simulation results along the same MAVEN orbit, we note that there is no significant variation in the Martian lower ionosphere. Finally, both bow shock and magnetic pileup boundary (BS, MPB) locations are decreased from (1.2 RMars, 1.57 RMars) at the pre-ICME phase to (1.16 RMars, 1.47 RMars) respectively during the sheath phase along the dayside Sun-Mars line.

MAVEN has provided a great opportunity to study the evolution of the Martian atmosphere and climate over its history. A large quantity of useful data has been returned for future studies. These kinds of data-model comparisons can help the community to better understand the Martian upper atmosphere response to the (extreme) variation in the solar wind and its interplanetary environment from a global perspective.

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