Dust Activities in the Southern High-latitudes of Mars

Dust activities in the southern high-latitude region around the southern solstice period have been observed in many Martian years. Theses dust events occur near the southern cap-edge region and play a major role in the observed dust climate. However, they generally cannot be simulated in the existing Mars general circulation models. In this report, we will introduce a parameterization scheme for simulating these dust events in the Mars climate model MarsWRF. In this scheme, the dust lifting threshold stress is adjusted with the surface temperature difference between the regolith and ice in the southern polar region. By this approach, dust events in the southern cap-edge region have been simulated around the southern solstice period. As a result, the simulated temperature in the southern high-latitude region is increased and the resulting vertical temperature profile is closer to that from observation. In addition, westward propagating dust events observed in a previous study have been simulated with a propagating speed similar to that observed. Results of numerical experiments suggest that the flow associated with the sublimation of the CO₂ ice in the southern cap edge is very important to the occurrence of these dust events in this region.