The Global Circulation

Abstract

Mars is a relatively small, desert planet with only a thin atmosphere at present. These basic properties are all directly reflected in its global circulation, which is fundamentally similar to that on Earth in many ways, but very different in other ways. The investigation of the global circulation of the Martian atmosphere has a surprisingly long history, as a result of the basic terrestrial similarities and the very early spacecraft missions to Mars. The virtual explosion in spacecraft observations during the last two decades has made the global atmospheric circulation of Mars by far the best characterized and understood atmospheric circulation in the Solar System, other than that of Earth. By comparison with Earth our knowledge of the global atmospheric circulation of Mars remains quite limited: there are extremely few direct wind observations, very few surface pressure observations, and the local time coverage of the global observations is very limited. Our knowledge of the planetary boundary layer (which can be extremely deep by comparison to Earth) on Mars is limited at present. It is only with the aid of extensive numerical modeling that our fundamental understanding of the global circulation of the Martian atmosphere has been fleshed out. Data assimilation efforts for Mars are still at a relatively early stage but these certainly have great potential for the future – if observations of the global atmosphere continue to be obtained.