北京地区对流层中上部云和气溶胶的激光雷达探测

Lidar Measurements of Cloud and Aerosol in the Upper Troposphere in Beijing

介绍了近年来研制的一台多波长激光雷达及其探测对流层高云和气溶胶的实验 ,并依据探测结果重点分析了北京 2 0 0 0年 1月至 4月对流层上部云和气溶胶在 5 32nm波长的消光系数分布特征。结果表明 :从 6km至 1 1km的气溶胶光学厚度值在 0 0 1 5 2至0 0 2 84之间变化 ,均值为 0 0 1 92。从 6km至 1 1km的云光学厚度值在 0 0 1 4至 0 2 3之间变化。观测到的单层高云的厚度最大为 6km。 4月 6日 ,近年来最强的一次沙尘暴袭击北京。 4月 7日北京地区无可见云 ,激光雷达探测结果表明 ,从 4km至 1 0km高度范围内 ,存在一层厚度约为 6km的气溶胶粒子层 ,消光系数峰值处于 8km附近 ,比晴天无云时的消光系数值约大一个数量级。估计这是一层沙尘气溶胶 ,系由远距离输送至北京形成的。

A new multi-wavelength lidar is introduced. The characteristics of 532 nm extinction coefficient profiles of cloud and aerosol in the upper troposphere in Beijing from January to April, 2000 are emphatically analyzed.Results show that the aerosol optical depth between 6 km and 11 km changes from 0.0152 to 0.0284 with a mean value of 0.0192?The cloud optical depth between 6 km and 11 km ranges from 0.014 to 0.23. The largest cloud thickness is about 6 km. On April 6, a very strong dust storm appeared over Beijing area. On April 7, there was no visible cloud; while as shown in lidar measurements, there was an aerosol layer spread from 4 km to 10 km. This aerosol layer, estimated as the sand-dust layer transported from remote desert areas, has the largest extinction coefficient at the height of about 8 km,which is about one order of magnitude larger than that in the clear (no cloud) day.