TES monitored the growth and decay of the 2001 global dust storm. Each year regional dust storms occur during the southern hemisphere summer season. Clouds of dust also appear near the edge of the polar caps prior to the onset of a regional dust storm and over the polar cap during the storms.
In June 2001, a small dust storm broke out in the Hellas impact basin. As TES watched from orbit, the disturbance grew until by late July it enveloped the whole planet in clouds of dust. The storm then slowly subsided over the succeeding months.