Presentation #213.10 in the session Martian Aurora, Atmosphere, Winds, and Dust (Poster + Lightning Talk)
Martian planet-encircling dust storms develop rapidly and often have no definitive cause. Hellas Basin–one of the most dominating topographic features on Mars– is a location that is closely associated with the genesis or enhancement of local and global dust storms. This study examines the role of atmospheric processes in the Hellas region in the initiation of global dust storms. Through time and spatial mean and perturbation analysis of the circulation, temperature, and surface pressure from NASA Ames General Circulation Model output, the movement and interaction of different types of waves in and around Hellas are characterized. Histograms of surface wind stress over 10 Mars years indicate that maximum stress events consistently fall between Ls 180-192 and between 0000-0600 local time. Within the region bounded by -70N to 0N latitude, 24E to 120E longitude, all these events are located in the Southwest region of Hellas Basin. The highest stress events were further classified into three types of storms based on the location and pattern of the perturbation surface pressure and near-surface winds. In each scenario, a strong southerly wind is identified, suggesting each maximum stress event is generated through constructive interference of some combination of the polar CO2 thermal circulation and diurnal topographic circulations that align with the anomalous southerly wind. Previous work has analyzed these individual circulations, but this paper seeks to precisely quantify their contributions to maximum surface stress events. The constructive interference of pressure systems in Hellas Basin, combined with the Southerly wind, implicate a small number of strong traveling eddies (baroclinic eddies) with specific paths or orientations in the most extreme surface stress events. These relatively rare, high amplitude systems with optimal locations and trajectories may be a prime contributor to storm initiation in the region and may be credited as the source of Mars’ violent dust storms.