Visual and infrared observations of wind streaks on Mars

Estimation of surface properties and physical setting of three common Martian wind streak types (bright, dark, and splotch related) provides constraints on models of the formation and variability of streaks. Bright streaks form independently of surface properties other than local topography. This is consistent with their formation being due to deposition of atmospheric dust in the lee of topographic features. Although they are widespread on Mars, dark streaks are noted as variable only in regions near 30°S latitude and elevations between 3 and 7 km, and are associated with dark surfaces that have relatively high thermal inertias. Splotch-related streaks occur at elevations between 0 and 6 km and in regions of relatively high thermal inertia. Splotch-related streaks occur near the boundaries of thermally defined regions, such as the south polar cap and other areas of either low or high thermal inertia. These thermal conditions are responsible for the production of surface winds which form and modify these streaks. The source of sidements which form splotch-related streaks varies from dunes to well-indurated stratified deposits. Regional studies of the various types in Syrtis Major, Syria Planum-Claritas Fossae, Oxia Palus, Mesogea, and Pettit craters and Noachis confirm that the correlations found at the global level occur at regional scales.