Large amplitude perturbations in the martian exosphere seen in MAVEN NGIMS data

We examine 252 Mars Atmosphere and Volatile EvolutioN (MAVEN) passes through the Martian atmosphere for which the Neutral Gas and Ion Mass Spectrometer (NGIMS) altitude-density profiles show perturbations with amplitudes larger than 40% of the background density that persist above the nominal exobase as defined here. The density profiles exhibiting such perturbations are plotted as a function of atmospheric column density rather than altitude. This roughly removes the dependence of the altitude-density profiles on composition, scale height, and local solar time. Such density structures are of interest as they can affect the local heating rate and, possibly, the escape rate. We find that the observed structures dissipate at roughly the same atomic column density and they affect the composition of the exosphere, raising the O/CO2 ratio as compared with orbits that do not exhibit significant perturbations.