激光雷达在沙尘观测中的应用——2004年春季北京和呼和浩特沙尘天气的解析

Application of Lidar in Sandstorm Observation——Analysis of dust events of Beijing and Hohhot in spring of 2004

2004年春季（2003年12月至2004年5月）利用激光雷达在北京和呼和浩特对沙尘天气进行了连续观测。利用激光雷达的数据导出了沙尘和大气污染物气溶胶消光系数的关系，对两个地点的沙尘天气特征和大气污染特征进行了探讨。该期间在呼和浩特观测到较大型的沙尘事件（消光系数大于0．3·km^-1）有9次，这些起源于蒙古国/内蒙古的沙尘事件晚于呼和浩特6～10h在北京被观测到。在呼和浩特观测到的沙尘云块的高度普遍较低（由地表至高空1～2km），而在北京较高一般可达到2～4km，同一沙尘事件的最高浓度（消光系数）是呼和浩特高于北京。在北京观测到的沙尘天气共有17次，其中包括数次小规模的沙尘事件在呼和浩特未观测到。从北京及呼和浩特的观测结果可以看出，北京地区3～5月沙尘的背景浓度高于呼和浩特，北京地区具有明显的区域规模大气污染特征，而呼和浩特只具有局部规模的大气污染特征。

Continuous observations of sand-dust storms in Hohhot and Beijing were made by polarization Lidar from Dec. 2003 to May. 2004. The relationship between dust and spherical aerosols extinction coefficient was given here, and also the characteristics of dust events and local air pollution were discussed in this article. During this period, 9 serious dust events were observed （extinction coefficient≥0.3· km^- 1 ） not only in Hohhot but were also found 6-10 hours later in Beijing, which verified that these dust-storms came from Mongolia and Inner Mongolia. The dust clouds in Beijing were about 2-4 km high above the ground, which were higher than that in Hohhot with 1-2 km high dust cloud. In Beijing 17 dust events were observed including some small scale dust events which were not observed in Hohhot. The observation results of Lidar show that the aerosol background concentration in Beijing was higher than Hohhot＇s, and Beijing＇s pollution level were effected not only by Inner Mongolia but also by surrounding area, while Hohhot＇s pollution only represented the local district condition.