| Local and major dust storms play a dominant role in contemporary aeolian processes on Mars. As a means of better documenting the role of dust storms on the surface, a record of their occurrence during the four years of the Viking Mission has been established using thermal infrared and visual observations. The dust storm record was then compared to observations of the martian surface. Particle transport, source region characteristics, and effects of dust storms, proximal and distal to their source are considered for both the Earth and Mars.; The martian atmosphere was determined to be dust-laden at all times. Maximum capacity occurs during southern spring and summer and is due to increased numbers of local dust storms. Based on the number of observed clouds, an estimated 100 local storms occur annually. Most are associated with winds along the receeding south polar cap and peak surface heating in the southern hemisphere near perihelion. Specific regions appear to be recurrent sources for the clouds and are characterized as having sandy surfaces. A survey of dune fields on Mars shows that while many source regions are sandy, large dune fields are limited to less than one percent of the plant, suggesting that if source regions needs a large sand component, they may be limited in extent. Dune fields, many of which may be active, are often observed near possible sources indicating that remobilization of clastic deposits may be an important contemporary process. Distal effects of dust storms appear to vary as a function of local and regional surface properties, topography, and latitude.; Basic elements necessary for a dust storm on Earth and Mars (i.e., adequate winds, sufficient sediment supply, and surfaces susceptible to erosion) are similar. The frequency, intensity, and geologic impact of dust storms, however, differ due to variations in these elements. On Mars, large temporal and spatial variations in atmospheric pressure and temperature are the primary control on dust storm occurrence. On Earth, sediment supply and surface conditions appear to be the more variable factors. On both planets, however, these conditions are related to climatic cycles. |
