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S. C. R. Rafkin, M. R. Sta. Maria, T. I. Michaels (San Jose State University)
The existance of mesoscale atmospheric circulations on Mars is well documented, primarly through images of enhanced dust loading and clouds which arise due to these circulations. The Mars Orbiter Camera imaged one such feature--a spiral dust cloud--over the caldera of Arsia Mons. We use the Mars Regional Atmospheric Modeling System to investigate the underlying dynamics of the dust cloud. Results show that the cloud feature is the visible portion of a much larger thermal circulation that vents boundary layer air to an altitude in excess of 30 km on time scales of only a few hours. At the top of the circulation, air and dust is transported horizontally over several thousand kilometers. The circulation is a warm-core low pressure system that has a structure not unlike hurricanes on Earth. Similar circulations are thought to be forced by other large topographic features. When taken as an ensemble, the mass flux and transport capabilities of these circulations may well be sufficient to maintain the background atmospheric dust load, and may play a crucial role in the transport of water and other volatiles. The transport by the circulations is also placed in the context of the slow and relatively diffusive transport of the Hadley Cell circulation. ~
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Bulletin of the American Astronomical Society, 34, #3< br> © 2002. The American Astronomical Soceity.