2021年中国北方首次沙尘天气的多源遥感分析

Multi-source remote sensing analysis of the first sand and dust weather in Northern China in 2021

利用多源遥感数据和NCEP再分析资料,从沙尘源区的地理环境和气候特征出发,对2021年中国北方首次沙尘天气事件每日的大气环流形势以及沙尘的水平,垂直分布特征进行深入的研究分析.结果表明:源区内异常增温,降水稀少的气候背景下致使大面积裸露松散的土壤含水量较低,为大范围,高强度沙尘天气的形成提供了物质基础;频繁活动的冷空气,是沙尘天气爆发的动力因子.沙尘在强风中沿东南方向向下游地区输送和扩散,中国西北,华北,黄淮,江淮,江汉地区和江南北部等地先后受到沙尘天气的影响,空气质量迅速恶化,首要污染物为PM_(10).此外,沙尘气溶胶东移也波及朝鲜半岛,日本等下游地区.在输送过程中,内陆地区沙尘主要分布在1~6km,而下游地区的沙尘则集中分布在2km高度附近,粒径较大的沙尘出现在近地表的频率较高,较小的颗粒主要分布在对流层中下层.

The daily atmospheric circulation situation and both the horizontal and vertical distribution patterns of sand and dust during the first dust weather event in Northern China in 2021 are investigated by using multi-source remote sensing data and NCEP reanalysis data and taking account of the geographical environment and climatic characteristics of the dust source area.The results showed that the abnormal temperature increase and scarce precipitation in the source area lead to a decrease in water content for a large-area bare and loose soil,providing a material basis for the formation of large-scale and high-intensity sand and dust weather;moreover,the frequent activities of cold air turned out to be the driving factor for the outbreak of sand and dust weather.Sand and dust were transported and diffused along the southeast direction in strong winds to the downstream areas.Northwest China,North China,Huanghuai,Jianghuai,Jianghan and northern Jiangnan were affected by sand and dust weather in sequence,where air quality were rapidly deteriorated with the primary pollutant PM_(10).In addition,the eastward migration of sand and dust aerosols also affected downstream areas such as the Korean Peninsula and Japan.During the transportation process,the sand and dust in the inland areas were mainly distributed in the altitude from 1to 6km,while the sand and dust in the downstream areas were concentrated near the height of 2km.The dust with larger particle size appeared more frequently near the surface,while the smaller particles were mainly distributed in the middle and lower troposphere.