The Martian escape rate as a function of upstream solar conditions

Robin Ramstad1, Stas Barbash2, Yoshifumi Futaana2, Hans Nilsson2 and Mats Holmstrom2, (1)Department of Astrophysical and Planetary Sciences, University of Colorado Boulder, Laboratory for Atmospheric and Space Physics, Boulder, United States, (2)IRF Swedish Institute of Space Physics Kiruna, Kiruna, Sweden
Abstract:
We investigate potential factors for influence on the Martian heavy ion escape rate (Q) by integrating Mars Express ASPERA-3/IMA heavy ion flux measurements in the Martian tail, taken at similar (binned) solar wind density (n), velocity (v) and EUV radiation flux (FEUV) upstream conditions. In the best sampled cases, with v and FEUV constrained, we find a statistically significant decrease in heavy ion escape rate with increased solar wind density. An empirical-analytical model for atmospheric escape is developed by fitting calculated escape rates to all sufficiently sampled solar conditions, indicating an overall negative dependence on solar wind density.
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