Lidar Measurements of Cloud and Aerosol in the Upper Troposphere in Beijing
北京地区对流层中上部云和气溶胶的激光雷达探测

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.