Circulation Atmospheric circulation is similar to that of Earth. Very cold poles. In winter, CO2 freezes out of the atmosphere. This CO2 frost causes the atmospheric pressure to decrease Creates winds from pole to pole as one freezes and the other thaws. Ice goes directly to gas through sublimation .
Winds cause dust storms.
In 1971, Mariner 9 and 2 USSR missions. No definite evidence for or against. No organic compounds were detected. May be permafrost to 1 km deepth, and liquid water below. Base is a steep cliff Caldera at top is 80 km wide Volcano is located above a stoaionery mantle plume or hot spot.