Spatiotemporal Distribution of Snow Cover in Arid Regions in China

Based on MODIS and AMSR-E combined cloud-free snow cover product,in this paper the snow cover duration days(SCD),snow cover onset date(SCOD) and snow cover ending date(SCED) in arid regions of China were calculated and evaluated for 8 hydrological years from 2002 to 2009.Spatiotemporal distribution of snow cover in the study area was analyzed through mapping of SCD and statistical results of snow cover area(SCA).The results are as follows:(1) The compared results reveal that the accuracy of snow cover parameters extracted from remote sensing images is high and close to the data observed at the weather stations,the duration errors are mostly within 20 days;(2) Except for the regions covered with glaciers and firn in the alpine zone,north Xinjiang between the Tianshan Mountains and Altay Mountains is the region with the thickest seasonal snow cover,SCD was mostly longer than 60 days,but the distribution of seasonal snow cover is uneven.Holistically,the SCD becomes shorter,the SCOD becomes later and SCED becomes earlier from the marginal zone of the mountains to the central area of the basins;(3) The total areas of snow cover in arid regions were comparatively large in 2005,2007 and 2002 but small in 2008 and 2006,respectively;The area and distribution of stable snow cover were comparatively stable,with the inter-annual changes being mainly the fluctuation of the number of SCD;the area of unstable snow cover were generally larger than stable snow cover,with obvious inter-annual fluctuations and the number of SCD mostly lower than 20.