Quantifying the atmospheric impact of local dust storms using a martian global circulation model

Abstract

We investigate the modelled impact on the global atmosphere of local dust storm simulations on the martian atmosphere. The investigation utilises existing observations from Mars Global Surveyor’s Mars Orbiter Camera and the Thermal Emission Spectrometer instruments, and the UK version of the LMD Mars Global Circulation Model. A typical example investigated here is a local dust storm in the Terra Sirenum region centred at (40∘S, 146.5∘W), with lateral coverage of ∼2.1E+5 km2 and peak optical depth of 0.7. We find atmospheric cooling, initially mainly restricted to the planetary boundary layer, by up to 8% (-14 K) during the night of the first sol with a consequential abrupt rise (+15 K) on the following sol, compared to the pre-storm diurnal range of 175–210 K at this location. Divergent wind currents, with a high-pressure centre, develop on the first day of the storm resulting in changes in both wind components up to three times their base values (±10m∕s). Atmospheric densities above 15 km altitude exhibit a peak increase of +9% from pre-storm values, while surface pressures show less change ±3%. Dynamical changes triggered by a local dust storm are quantified and their importance are thus considered in the context of potential future Mars spacecraft missions.