2007—2017年中国沙尘气溶胶的三维分布特征及输送过程

Three-dimensional Distribution and Transport Process of Dust Aerosols over China from 2007 to 2017

利用最新发布的CALIPSO产品,构建了2007-2017年中国沙尘气溶胶的三维分布,并结合HYSPLIT-4模式和再分析数据,探讨了沙尘的三维输送过程。结果表明:中国的沙尘排放源区主要是塔克拉玛干沙漠和巴丹吉林沙漠,沙尘气溶胶出现频率分别为60%和35%。塔克拉玛干沙漠排放的沙尘主要(50%~70%)停留在源地0~6 000 m高度,少部分向东输送至甘肃和内蒙古;巴丹吉林沙漠排放的沙尘则主要向东输送。中国沙尘排放量在春季最大,向东输送最强;夏季,东亚夏季风限制了沙尘向东输送;秋季,沙尘排放减弱,输送强度和夏季相当;沙尘排放量在冬季最小,输送最弱。夏季,沙尘在输送过程中可被抬升至高度5 000 m以上,春季次之,秋、冬季的沙尘主要在低层大气输送。沙尘在向东输送的过程中被抬升并和当地人为污染物混合变为污染性沙尘,华北地区污染性沙尘出现频率高达30%;输送到海洋的沙尘也会与洋面上(0~3 000 m高度)的海盐气溶胶混合,出现频率约为10%。

In this paper, the three-dimensional distribution and transport process of dust aerosols over China are discussed by combining reanalysis data, CALIPSO products and the HYSPLIT-4 model. The results show that these dust aerosols are mainly sourced from the Taklimakan and Badain Jaran deserts with occurrence frequencies of 60% and 35%, respectively. Dust aerosols emitted from the Taklimakan Desert mainly(50%-70%) stay at 0-6 000 m height, and some of them can be transported eastward to the provinces of Gansu and Inner Mongolia. Dust aerosols emitted from the Badain Jaran Desert mainly affect the eastern part of China through long-distance transport. In spring, the dust emission is the largest and the eastward transport intensity is the strongest;In summer, the eastward transport of dust is restricted by the East Asia monsoon;The dust emission is weakened in autumn and the transport intensity is equivalent to that in summer;In winter, the dust emission is the smallest and the transport intensity is the weakest. Dust aerosols can be lifted up to high altitude more than 5 000 m during the transport process in summer, followed by spring. The dust transport in autumn and winter is mainly limited in the lower atmospheric layer. During the eastward transport, dust aerosols are lifted up and polluted by the local anthropogenic pollutants. The occurrence frequency of polluted dust aerosols over north and east China is up to 30%. The dust aerosols transported to the ocean can be mixed with sea salt(0-3 000 m height) and the occurrence frequency is about 10%.