协同地基和空基激光雷达的沙尘天气观测研究

Observation and Analysis of a Sand-dust Weather by Cooperative Ground-based and Space-Brone Lidar

利用紫外地基激光雷达,结合CALIPSO星载激光雷达、MODIS产品对2019年10月28日至29日南京地区一次沙尘污染过程进行观测研究。结果表明沙尘粒子28日开始进入南京,29日达到污染高峰,污染主要集中在2500 m高度范围内。沙尘气溶胶易出现分层现象,上层粒子直径较小,下层粒子直径较大,随时间推移上层小粒径沙尘不断沉降,在近地面与下层污染混合、累积,导致近地面消光系数持续增高,进而引起局地沙尘污染现象。结合HYSPLIT后向轨迹分析结果,判定此次南京地区沙尘污染为外部输入,沙尘可能来源地为内蒙古、蒙古地区,沙尘粒子随冬季风由北往南输送,在此过程中不断沉降、累积,造成区域性污染天气。

The ultraviolet ground-based lidar,CALIPSO and MODIS product were used to observe and study a dust process in Nanjing area on October 28~29,2019.The results showed that dust particles entered Nanjing on October 28 and reached the pollution peak on October 29,with the pollution mainly concentrated in the range of 2500 m.Dust aerosol proned to be stratified,with the upper particles having a smaller diameter and the lower particles having the larger one.With the passage of time,the dust of the upper particles with small size continuously settled,mixed and accumulated with the substratum particles in the near surface,resulting in the continuous increase of the extinction coefficient of the near surface,thus causing local dust pollution.Com‑bined with the results of HYSPLIT backward trajectory analysis,the dust pollution in Nanjing area was deter‑mined as an external input,and the dust source area was Inner Mongolia and Mongolia.The dust particles were transported from north to south with the winter wind,continuously settled and accumulated in this process,re‑sulting in regional polluted weather.