中国西北春季沙尘高发区及沙尘源解析

以波段亮温差算法（BTD）对中国西北2014~2018年春季460期MODIS L1B数据进行沙尘信息逐日提取,统计分析沙尘频数的空间分布规律,结合地貌特征及地表沉积物细颗粒组分含量进行沙尘源解析.结果表明：（1）中国西北沙尘活动呈"两区三带"分布特征,沙尘频发区主要分布于塔里木盆地和蒙古高原南部沙漠戈壁区;区内存在塔克拉玛干沙漠东南缘荒漠绿洲高频带（270~287次）、库姆塔格沙漠北缘高频带（240~250次）及巴丹吉林沙漠东北边缘荒漠绿洲高频带（240~250次）.（2）中重度沙尘高频区主要分布于塔克拉玛干西北部沙漠绿洲.沙尘源主要为富含粉尘的边缘沙漠与冲积洪积扇缘戈壁交错带,内含丰富的干河床、干涸湖泊和绿洲退化地,该区域细物质组分含量高,易释放粉尘微粒并通过局地循环过程向周边地表扩散沉积,为区域高频、高浓度沙尘发生提供丰富的物质基础.

Identify high frequent dust areas and their sources in spring in the Northwest of China

The spatial distribution of dust frequency was extracted from MODIS L1B data of 460 days in spring from 2014~2018 in the Northwest of China by using brightness temperature difference (BTD) algorithm and dust source was identified by combining with the geomorphological type and the content of fine particles in surface sediments. The results showed that dust activity in the region is characterized as two regions and three belts in which the two regions are Tarim Basin in Xinjiang Autonomous Region and Gobi Desert of southern Mongolian plateau and the three belts are desert oasis in southeastern margin of Taklimakan Desert (270~287 times), northern margin of Kumutag Desert (240~250 times), and desert oasis in the northwestern margin of Badain Jaran Desert (240~250 times). The region with high frequency of moderate and severe dust activities is mainly located in desert oasis of the northwest margin of Taklimakan. The dust source is mainly located in the transit zones from Alluvial fan, via Gobi, to the edge of Desert filled with dry riverbed, dry lake, and degraded oasis. The surface in the region covers fine sand particles and provide rich sand material for the high-frequent and high-concentrated sand and dust. The fine particles are easy to release to atmosphere and diffuse to the surrounding region through the local dust circulation process.