Effects of a solar flare on the Martian hot O corona and photochemical escape

Document Type


Publication Date



Physics and Astronomy

Publication Title

Geophysical Research Letters


We examine for the first time the flare-induced effects on the Martian hot O corona. The rapid ionospheric response to the increase in the soft X-ray flux (~800%) facilitates more hot O production at altitudes below the main ionospheric peak, but almost all of these atoms are thermalized before escape. In response to the increase in the extreme ultraviolet (EUV) flux (~170%), the overall upper ionospheric and thermospheric densities are enhanced, and the peak thermospheric responses are found ~1.5 hr later. The photochemical escape rate is predicted to increase by ~20% with the increases in the soft X-ray and EUV fluxes but decrease rapidly by ~13% about 2.5 hr later before recovering the preflare level. Since escaping hot O atoms are mostly produced at high altitudes where ionization by the EUV flux is the greatest, the main contributor to the 20% increase in escape rate is the enhancement in the EUV flux.

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