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F. Forget, F. Hourdin, C. Hourdin, O. Talagrand (Laboratoire de Meteorologie Dynamique, CNRS, Paris, France.)
To improve our knowledge of the dust cycle, key to the Mars climate, we have developed an interactive dust transport model within our general circulation model (GCM) of the martian atmosphere. The model accounts for the lifting of the dust by the near surface winds, the vertical mixing in the turbulent boundary layer and by atmospheric convection, the advection by the general circulation, gravitational sedimentation and even a possible ``scavenging'' by CO2 clouds in the polar regions. Multiple particle sizes are simultaneously taken into account. The model is used to better understand the coupling between the dust cycle and other climate processes, and to interpret the available observations. For instance, it has been possible to reproduce the latitudinal and seasonal variations of the altitude of the top of the dust layer as observed by Mariner 9 and Viking. However, the lifting of the dust from the surface and the resulting seasonal cycle have been found to be extremely sensitive to model properties such as horizontal resolution or topography. Although some versions of the model can agree well with the observations, other versions, slightly different, can lead to very unrealistic behavior. This shows that understanding and parametrizing the processes actually at work on Mars will be challenging.
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The author(s) of this abstract have provided an email address for comments about the abstract: forget@lmd.jussieu.fr