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[9.04] Modelling of local and regional weather phenomena in the Sagan Memorial Station (Mars Pathfinder) landing area during its operation; an update

T. Siili, A.-M. Harri (Finnish Meteorological Institute / Geophysical Research), H. Savijärvi (Department of Meteorology / University of Helsinki), G. R. Wilson (Jet Propulsion Laboratory)

The Mars Pathfinder landed in the Ares Vallis at 19.17\degN, 33.21\degW on 1997-07-04 (corresponding to late summer or L_s \approx 143\deg) and operated until 09-1997. The lander is located on a gentle large-scale slope which also exhibits surface albedo and thermal inertia gradients. We have modelled some boundary layer and mesoscale phenomena occurring in the Lander region using the Dep. of Meteorology / Univ. of Helsinki (DMUH) 1-D and 2-D Mars atmospheric models.

The 1-D model has high vertical resolution as well as a multi-layer surface and soil temperature prediction scheme; as a result the model reproduces the Pathfinder diurnal and vertical air temperature variations highly satisfactorily. The fitted temperature variations also provide estimates of the heat capacity and the thermal conductivity (thermal inertia) of the underlying soil.

The 2-D mesoscale model has been used to model explicitly the winds driven by the slope as well as by the surface albedo and soil thermal inertia gradients in the landing area. New and revised simulations incorporating, \emph{e.g.}, Pathfinder data for dust optical thickness, have been carried out. The model-derived wind information has been compared with wind data from the Pathfinder ASI/MET instrument.