Seasonal variations of storm zones on Mars

Using the NASA Ames Mars general circulation model, an annual cycle simulation has been performed corresponding to a low atmospheric dust loading. Surface pressure time series near the Viking Lander 2 location have been analyzed using singular spectrum analysis (SSA) and autoregressive models to isolate statistically significant spectral power. Also, circulation statistics have been separated using band-pass time filtering and analyzed for coherent spatial patterns. During northern autumn, winter and spring seasons, localized ‘storm zones’ can occur which are particularly strong within the lowlands of Arcadia, Acidalia and Utopia planitia. During early northern spring, the transient eddy activity is stronger than that found during any other season. With weakening baroclinicity accompanying seasonal transition toward midspring, the eddies become less vigorous and the associated storm ‘belt’ shifts into higher latitudes. Since transient baroclinic eddies are active agents in the transport of heat, momentum and moisture in middle latitudes, variations in the storm zones during the seasonal cycle will have important implications for Mars' regional climate.