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J. M. Bell, S. W. Bougher (University of Michigan), J. R. Murphy (New Mexico State University)
Interannual variability remains a key ingredient in the validation of existing Martian atmospheric models and their predictions. There is presently no comprehensive empirical model of the Mars upper atmosphere. Instead, satellite mission planners require reliable Thermospheric General Circulation Model (TGCM) results in order to aerobrake properly. Thus, understanding the repeatability of Martian dust storms and their effects in the upper atmosphere is crucial to making reasonable projections at aerobraking altitudes (Liu, Richardson and Wilson 2003). As an example, the phenomenon known as winter polar warming occurs in the Martian lower themosphere and is observed in the ~100-130 km Mars Global Surveyor Phase 2 (MGS2) aerobraking data (approaching aphelion) and Odyssey aerobraking data (approaching perihelion) (Keating et al., 2003; Bougher et al., 2004). Previous research by Bell et al (2004) illustrates that deep vertical dust-mixing in the lower atmosphere results in an enhanced inter-hemisphere circulation that yields dynamical (adiabatic) heating in the winter polar region. This polar warming is most pronounced during Mars perihelion conditions. The present research compares model simulations from the coupled MGCM-MTGCM using Mars Global Surveyor Thermal Emission Spectrometer mapping year 1 (TES1) and TES mapping year 2 (TES2) dust opacity data. In TES2, a regional dust storm occurs in the summer hemisphere during the period of Ls = 180 to 270 (Liu, Richardson and Wilson 2003), whereas no similar structure exists in the TES1 data during the same time period. Thus, the coupled simulations in the present research illustrate the first detailed attempt at quantifying the interannual variations at thermospheric altitudes due a dust-storm in the Mars lower atmosphere.
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The author(s) of this abstract have provided an email address for comments about the abstract: jmbell@umich.edu
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Bulletin of the American Astronomical Society, 36 #4
© 2004. The American Astronomical Soceity.