DESCRIPTION OF THE MARTIAN POLAR-CAP BREEZE

The surface temperature of the Martian polar caps is about 148 K (fros t point temperature of CO2 at a surface pressure of about 6 hPa), with the ''desert'' (frost-free) areas adjacent to the polar caps having m uch greater surface temperatures. The existence of this steep meridion al gradient of temperature between the polar caps and the adjacent ''d esert'' areas may produce in the atmosphere a baroclinic instability w hich generates an atmospheric circulation system similar in some aspec ts to the terrestrial sea breeze. We have called this circulation syst em the Martian polar cap breeze. In this paper, the phenomenology of t he Martian polar cap breeze is developed on the basis of the indirect observational evidence. Along with friction and the Coriolis force, ot her factors influence the polar cap breeze: the prevailing wind, topog raphy, irregularity of the polar cap-edge, and stability of the atmosp here. These factors are studied in a qualitative form, as well as the seasonal variations. In addition, the large-scale polar cap wind is pr esented as a different Martian atmospheric circulation system.