资源环境科技发展态势分析平台

We study the 2018 Martian global dust storm (GDS 2018) over the Southern Polar Region using images obtained by the Visual Monitoring Camera (VMC) on board Mars Express (MEx) during June and July 2018. Dust penetrated into the polar cap region but never covered the cap completely, and its spatial distribution was nonhomogeneous and rapidly changing. However, we detected long but narrow aerosol curved arcs with a length of similar to 2,000-3,000 km traversing part of the cap and crossing the terminator into the nightside. Tracking discrete dust clouds allowed measurements of their motions that were toward the terminator with velocities up to 100 m/s. The images of the dust projected into the Martian limb show maximum altitudes of similar to 70 km but with large spatial and temporal variations. We discuss these results in the context of the predictions of a numerical model for dust storm scenario.

Plain Language Summary Dust storms of different scales (local, regional, etc.) are common on Mars. Some Martian years a regional storm activates secondary storms and dust encircles the planet, in a dust event usually called a global dust storm. The last global dust storm took place in 2018, and we are not currently able to predict when a new one will occur. Global dust storms affect the global dynamics of the Martian atmosphere, and the dynamics of the polar regions is a good proxy to the global situation. In this paper, we take advantage of the polar orbit of Mars Express to study the Southern Polar Region during 2018 global dust storm using the Visual Monitoring Camera onboard the spacecraft. We show how the dust penetrated into the polar cap, the apparition of aerosol arcs curved around the pole, and the presence of winds blowing up to 100 m/s, not following the usual patterns expected with no global dust storm.