Global observations of Martian clouds with the Mars Orbiter Camera of the Mars Global Surveyor spacecraft

Abstract

We have studied the global cloud distribution on Mars using red and blue global map swaths taken by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC). In Chapters 1 and 4, we summarize the results for the first and second MGS mapping years, respectively. In Chapter 2, we investigate the mechanism for a new type of flushing dust storm first observed by MGS. These dust storms moved from the northern high latitudes southward across the equator, and led to a planet-encircling dust storm in the first MGS mapping year (1999). In Chapter 3, we track cloud motion to measure winds using images separated by 2 hours. The systematic daily global coverage of MGS not only provides us with detailed and coherent pictures of Martian cloud evolution, but also increases the number of cloud-tracked wind vectors by three orders of magnitude. Except for the global dust storm in the second MGS mapping year (2001), Martian weather is highly repeatable. When the 2001 global dust storm initiated, Hellas storms increased in frequency, transporting dust out of the basin daily. When the 1999 planet-encircling dust storm initiated, flushing storms also increased in frequency, transporting dust to the southern subtropics daily. These observations suggest that timely dust supply by local or regional storms could have a global impact.