Wang and others present a global, time-dependent simulation of the Mars upper atmospheric responses to an X8.2-class solar flare event on 10 September 2017. The solar flare irradiance is realistically specified and incorporated into the Mars Global Ionosphere-Thermosphere Model to simulate the flare effects.

The top row shows the MGITM-calculated horizontal distributions of (from left to right) neutral temperature, pressure, CO2, and O densities at 251.25 km altitude prior to the flare onset at 2017-09-10/15:00. The results describe the spatial variations in local time and MSO latitude, with the subsolar point in the plot center. The subsequent rows show the percentage differences between the baseline case and the flare case at 2017-09-10/16:15, 2017-09-10/18:45, and 2017-09-11/01:00, respectively.

The model results are in reasonably good agreement with the Mars Atmosphere and Volatile EvolutioN spacecraft measurements. It is found that the ionized and neutral regimes of the upper atmosphere are significantly disturbed by the flare but react differently. The ionospheric electron density enhancement is concentrated at the E region below ∼110 km altitude and closely relates with the time evolution of the flare. The atmospheric perturbation increases with rising altitude and takes ∼1.5 hours past the flare peak to reach the maximum disturbance. It takes the neutral atmosphere more than 10 hours to generally settle down to the pre-flare state.

Publication Name: Geophysical Research Letters

First HAO Author's Name: Wenbin Wang