  We study the 2018 Martian Global DustStorm (GDS 2018) over the Southern Polar
Region using images obtained by the Visual Monitoring Camera (VMC) on board
Mars Express 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 2,000-3,000 km traversing part of the cap
and crossing the terminator into the night side. Tracking discrete dust clouds
allowed measurements of their motions that were towards the terminator with
velocities up to 100 m/s. The images of the dust projected into the Martian
limb show maximum altitudes of around 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.
