Abstract:

On the basis of a previous algorithm of cloud detection, clouds and aerosols are distinguished by analyzing the backscatter signals of a micro pulse lidar. In this way, the content of clouds are classified into ice, water, mixed-phase clouds and horizontal oriented ice flakes. Finally, the supercooled water clouds are distinguished from water clouds by the information of temperature profiles. The monthly changes of the appearance heights and proportions of the various clouds are also calculated with one-year observations over the lidar site. The supercooled clouds are found to appear at 9.84% of all the cloudy time, and 11.99% of all the time for clouds at from 0℃ to − 40℃.

Key words: supercooled water clouds, micro pulse lidar, depolarization ratio, temperature profile

摘要：

在已有的云识别算法基础上, 利用微脉冲激光雷达后向散射信号区分云和气溶胶。按照云粒子的退偏振比, 区分冰云、水云、混合云以及水平导向的冰晶云。结合大气温度廓线, 对过冷水云层进行有效的识别。利用观测点上空持续一年的观测资料, 统计各种云出现的高度及比例的逐月变化, 结果显示, 过冷水云出现的时间占有云时间的9.84%, 对于0~−40℃的云层, 过冷水云出现的时间占11.99%。

关键词: 过冷水云层, 微脉冲激光雷达, 退偏振比, 温度廓线