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Y. O. Takahashi, Y.-Y. Hayashi, M. Odaka (Hokkaido University, Japan), W. Ohfuchi (Earth Simulator Center, JAMSTEC, Japan)
A high resolution simulation of the Martian atmosphere is performed to examine the appearance of small to medium scale atmospheric disturbances and their effects on the dust lifting and transfer processes. The dynamical core of the Martian GCM used in this study is that of the terrestrial GCM, AFES (Atmospheric GCM for Earth Simulator, Ohfuchi et al., Journal of the Earth Simulator, 1, 8, 2004). The physical processes of the present model are those developed by our group so far (the earlier version of our Martian GCM and its physical processes are described in Takahashi et al., JGR, 108, 5013, doi:10.1029/2001JE001638, 2003). A test simulation is performed with a relatively low resolution of T79L24, which is equivalent to about 90 km grid size on Mars. Moreover, this simulation is a "passive dust experiment" in the sense that dust is assumed to be radiatively inert. Atmospheric heating due to dust absorption is given separately from a zonally uniform distribution of dust with the latitudinal profile following the MGS-TES observation. The result of test simulation shows clear frontal structures in the baroclinic zones at spring and fall seasons. In addition, medium scale vortex generations are observed in the lees of high mountains in the northern hemisphere. In this test simulation, dust lifting events occur only in some limited areas and limited seasonal dates. Major dust lifting regions include the vicinity of polar caps, the eastern flank of Tharsis plateau, the southern low latitude belt, and the Hellas basin. These regions roughly coincide with those of dust storms observed by the MGS and dust lifting regions reported by earlier GCM studies. It is suggested that the strong wind, which is associated with the fronts and the local circulations induced by topographic variation, plays an important role to lift dust and generate dust storms.
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Bulletin of the American Astronomical Society, 37 #3
© 2004. The American Astronomical Soceity.