Solar Soft X‐Ray Proxy Derived From Observed Auger Photoelectrons by MGS and a 1999–2006 Flare Catalog at Mars

Abstract This study uses a novel approach to infer the solar soft X‐ray (SXR) irradiance from Auger photoelectron fluxes. Solar SXR irradiance is highly variable, particularly during solar flares. Solar SXR photons at 2.5 nm produce oxygen Auger photoelectrons by photoionizing atmospheric constituents. More specifically, we derive the fit function between the Auger photoelectron fluxes observed by Mars Global Surveyor (MGS) and the 0.1–0.8‐nm solar irradiance observed by the Geostationary Operational Environmental Satellite (GOES) X‐ray Sensors (XRS). The fit function is applied to the MGS data to produce a proxy for the 0.1–0.8‐nm SXR irradiance and to classify 167 identified solar flare events from 1999 to 2006 at Mars, which is an additional vantage point away from Earth. These results are of particular interest for studying Mars's atmospheric response to solar flares and over‐the‐limb and far‐side solar activities.