Orographically generated flow on Mars

A. WIIN NIELSEN, TORBEN RISBO

Abstract

The paper discusses the effect on the martian atmosphere of the distance between the center of gravity and the geometrical center of the planet. An approximate solution of the problem is obtained by considering the real surface as a large-scale orography with respect to a reference spherical planet. The resulting circulation has a maximum in the geopotential in the region, where the real planet is above the reference planet and a minimum in the geopotential on the opposite side. The resulting geostrophic winds have a strength of 10 to 30 ms-1. A second problem is the determination of the stationary quasi-geostrophic flow which is in equilibrium with the martian orography. The calculation is based on a specification of the martian orography in spherical harmonic functions with a triangular resolution in 16 components. This resolution is sufficient for the present purpose because the contribution from smaller features in the orography to the stationary flow pattern become negligible

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