Dust storm-enhanced gravity wave activity in the Martian thermosphere
observed by MAVEN and implications for atmospheric escape
Abstract
Lower atmospheric global dust storms affect the small- and large-scale
weather and variability of the whole Martian atmosphere. Analysis of the
CO2 density data from the Neutral Gas and Ion Mass Spectrometer
instrument (NGIMS) on board NASA’s Mars Atmosphere Volatile EvolutioN
(MAVEN) spacecraft show a remarkable increase of GW-induced density
fluctuations in the thermosphere during the 2018 major dust storm with
distinct latitude and local time variability. The mean thermospheric GW
activity increases by a factor of two during the storm event. The
magnitude of relative density perturbations is around 20% on average
and 40% locally. One and a half months later, the GW activity gradually
decreases. Enhanced temperature disturbances in the Martian thermosphere
can facilitate atmospheric escape. For the first time, we estimate that,
for a 20% and 40% GW-induced disturbances, the net increase of Jeans
escape flux of hydrogen is a factor of 1.3 and 2, respectively.