The seasonal and spatial distribution of textured dust storms observed by Mars Global Surveyor Mars Orbiter Camera

Local and regional dust storms observed by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) exhibit three main types of textures in their visible top structures which we describe as “pebbled”, “puffy”, and “plume-like.” In this paper, we present the temporal and spatial distribution of each texture type. There is a pause in activity near the solstices for all three texture types, but the pause is more pronounced for pebbled and plume-like dust storms than for puffy dust storms. The average size of each texture type is usually much larger during the northern summer and fall (Ls=90-270°) than during the rest of the Martian year. Although all three textures types can be observed at all latitudes, plume-like dust storms tend to dominate the northern mid-latitudes, pebbled dust storms tend to dominate the southern mid-latitudes, and puffy dust storms tend to dominate the low latitudes. During the 2001 global dust storm in Mars Year 25, we found a progression from a combination of all three texture types in the early stage to mostly plume-like dust storms in the expansion and decay phases.