Seasonal variability of Martian ion escape through the plume and tail from MAVEN observations

We study the Mars Atmosphere and Volatile Evolution spacecraft observations of Martian planetary ion escape during two time periods: 11 November 2014 to 19 March 2015 and 4 June 2015 to 24 October 2015, with the focus on understanding the seasonal variability of Martian ion escape in response to the solar extreme ultraviolet (EUV) flux. We organize the >6 eV O+ ion data by the upstream electric field direction to estimate the escape rates through the plume and tail. To investigate the ion escape dependence on the solar EUV flux, we constrain the solar wind dynamic pressure and interplanetary magnetic filed strength and compare the ion escape rates through the plume and tail in different energy ranges under high and low EUV conditions. We found that the total >6 eV O+ escape rate increases from 2 to 3 × 1024 s−1 as the EUV irradiance increases by almost the same factor, mostly on the 6 eV O+ ion escape rate increases from 2 to 3 × 1024 s−1 as the EUV irradiance increases by almost the same factor The tailward escape rate increases with EUV, while the plume escape rate does not change significantly The ratio of the plume escape to the total escape drops from ~30% to ~20% as the EUV increases