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Y. O. Takahashi, M. Odaka, Y.-Y. Hayashi (Hokkaido University, Japan)
Characteristics of the general circulations simulated by our Mars GCM are compared with the observational data. Three simulations are performed under the conditions of Viking year, Mars Pathfinder (MPF) year, and the Mars Global Surveyor (MGS) year, respectively.
The Mars GCM used in this study is the new version of that developed by Takahashi et al. [JGR, 108, doi:10.1029/2001JE001638, 2003]. The dynamical core is newly developed by using the spectral transform method instead of the finite difference method. The vertical mixing is now evaluated by the scheme of Mellor and Yamada [1982]. A 13-layer soil model is newly introduced. Mass exchange between the atmosphere and the polar caps is now incorporated. The resolution of model utilized in the present study is T21L40. The radiative effect of dust is considered. The distribution of dust opacity is given as an external condition. The vertical distribution of dust is give by following Conrath [1975]. In the Viking and MPF year simulations, we assume a horizontally uniform dust distribution with seasonal variation. In the MGS year simulation, we assume a zonally uniform dust distribution with a seasonally varying latitudinal profile determined from the MGS-TES observation.
The simulated seasonal variation of daily mean surface pressure at the site of Viking lander is quite close to that of observation. The meridional temperature distribution simulated by our GCM agrees well with the MGS-TES observation especially below about 20 km altitude. Above about 20 km altitude, however, the simulated temperature tends to be lower than the observed one by about 5 to 15 K. The amount of temperature difference is within the range of ambiguity of the vertical extent of dust profile. The temperature profile observed by the MPF is roughly reproduced by our GCM below about 30 km except for the temperature inversion.
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Bulletin of the American Astronomical Society, 36 #4
© 2004. The American Astronomical Soceity.