Character of dust weather and its relationship with snow cover during late fall and early spring in Gansu and Inner Mongolia

Based on in-situ monthly sand-dust days data atmeteorological stations and MOD10A2 data, which are 8-day composite snow cover observation at 500m spatial resolutionduring November and next March from 2000 to 2008. The spatial and temporal distributionof sand-dust weather and snow cover during late fall and early spring in Gansu and Inner Mongolia were investigated via monitoring sand-dust days and snow cover fraction. The correlations between sand-dust weather and snow coverwere analyzed. The result shows that there weretwo centersof sand-dust in the study area, i.e., the western XilinGol League in Inner Mongolia and the west of Alxaleague in Inner Mongolia to the north of Yellow river in Gansu. Whilethe most extensive and persistent snow cover was located in high latitude and elevation, where sand-dust rarely appeared. During late fall and early spring, the days of sand-dust with different intensity had seasonal variations withslight fluctuation at the beginning and then increased rapidly. The snow cover fraction is just the reverse, it increasedat first and then decreased. On the annual level, the sand-dust represented a significant reduction, andthe snow cover fraction exhibited a weak rising trend. Therefore, to some extent, the correlation between snow cover fraction and sand-dust days is negative. It indicates that snow cover has some restraining effects to sanddust weather, andthe inhibiting ability is closely related to the intensity of sand-dust, the amount of the snowfall, and the distribution of sand source.