DOI: 10.1029/2025JA034157">
 

Time‐dependent changes to the Martian upper atmosphere during different solar flare events: A comparative analysis

Document Type

Article

Publication Date

2025

Department/School

Physics and Astronomy

Publication Title

Journal of Geophysical Research: Space Physics

Abstract

In order to informedly characterize the effects that the Sun's flare irradiance may have on the upper atmosphere of Mars, the range of possible solar flare effects on this region must be considered. In the topside ionosphere of Mars, electron densities have ranged from roughly unchanged to as much as doubled during solar flare event observations. With global time-dependent simulations, the differences in these flare-driven ionospheric responses that are systematic (e.g., resulting from the timing after a flare's irradiance peak at which conditions are sampled) may be more readily distinguished from those that are caused by the atmosphere changing in different ways. In this study, the Martian topside ionosphere's response over time is investigated during three separate solar flare events (X14.4 flare on 15 April 2001, M7.8 flare on 26 April 2001, X8.2 flare on 10 September 2017) using time-dependent simulations from the M-GITM global atmospheric circulation model. To compare the flare events' simulated atmospheric effects, (a) main features of plasma density changes are characterized for each flare event, and (b) the atmospheric processes and sources that drive these changes are investigated. It is found that the flare events exhibited greatly differing magnitudes and durations of density changes, with ionospheric response shaped in part by rapid photochemistry with the unique, time-dependent flare irradiance profile for each event, and by the unique timescales over which the upper atmosphere thermally expanded. Differences of the flare events' MGS and MAVEN observations are interpreted in the context of these comparisons.

Comments

D. Pawlowski is a faculty member in EMU's Department of Physics and Astronomy.

Link to Published Version

DOI: 10.1029/2025JA034157

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