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P. Rogberg, S.R. Lewis, L. Montabone, P.L. Read (Dep of Physics, University of Oxford)
Almost three complete Mars years of assimilated data, based on observations by the Thermal Emission Spectrometer on the Mars Global Surveyor, have been used to study the spatially-resolved and varying properties of the Martian atmosphere on a synoptic scale. The observational data, consisting of primarily vertical temperature profiles below 40km and maps of total column dust opacity, have been assimilated into a comprehensive global circulation model (the Oxford MGCM). In this presentation, we will examine the seasonal and interannual variations of the zonal mean global circulation during the past three Mars years. A particular advantage of the data assimilation approach is its ability to derive synoptic maps of meteorological variables from incomplete and asynoptic observations. Including those for which no direct measurements are available, such as wind and surface pressure. Accordingly, we examine in some detail the reconstructed synoptic variability of mid-latitude cyclonic weather systems in both hemispheres during the assimilation period, comparing and contrasting behaviour in years with, and without, major dust storms. We investigate factors affecting this behaviour via comparisons with free-standing GCM simulations. In particular, we focus on the thermal structure of the atmosphere, for which a direct comparison with observations is available, and we examine the dynamical structure (winds and meridional circulation), trying to gain an insight into those phenomena which are not represented by the free-running GCM. As an example, we analyse the effects of the inter-annual variability of the atmospheric dust loading (due to different scales and timing of dust storms in the three years) on the dynamics of the mid-latitude atmosphere.
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Bulletin of the American Astronomical Society, 37 #3
© 2004. The American Astronomical Soceity.