中文摘要：

本文基于相对湿度廓线进入云层时的突变实现云底高反演的思想,采用2008年11月至2009年1月的COSMIC掩星湿空气数据反演全球云底高度,并与探空资料反演结果进行对比分析,得出以下重要结论：（1）当温度-40℃＜t＜0℃时,分别将云看作水云与冰云进行云底高反演,对比反演结果表明,该温度范围内若把云相态当作纯液相将造成高云及多层云的漏检测；（2）掩星对云底较低的低云云底高的反演效果不如探空仪,但对高云及多层云有更好的检测能力,且掩星反演结果普遍大于探空仪；（3）为深入分析掩星与探空仪同时检测到有云时的云底高反演差异,按照云层数相同与不同分别进行讨论.当云层数相同时,通过计算反演结果的平均偏差与标准偏差,发现二者在低纬地区差异最大,而且单层云的偏差较大,但多层云中三层云与四层云的反演结果比较一致；当云层数不同时,掩星检测的单层云在探空仪检测结果中“破裂”为多层云,导致二者反演结果存在较大偏差.

英文摘要：

Based on the idea of retrieving cloud-base height by using the mutation of relative humidity profile when it comes into cloud, this paper gets information of cloud-base height by using COSMIC wet air data from November 2008 to January 2009, and after comparing with the results retrieved from radiosonde data, it acquires the following important conclusions. （1）When the temperature of cloud layer is between 0 and --40 Celsius Degree, this paper retrieves the cloud-base height when cloud phase is respectively thought as liquid cloud or ice cloud, and finds that it may fail to detect high cloud and multilayer cloud if cloud phase is considered as pure liquid; （2）COSMIC gets worse cloud-base height results for low cloud and better ones for high cloud and multilayer cloud, and its retrieval results are generally greater than radiosonde＇s; （3） To further analyze the differences of retrieval results between COSMIC and radiosonde when they both detect cloud, this paper discusses the retrieval results respectively as their cloud-layer numbers are equal or not. When the cloud-layer numbers are equal, the differences are larger in low-latitude regions and for the single layer cloud by calculating their mean and standarddeviation, but they have consistent results for three-layer and four-layer cloud. When the numbers are different, some single layer clouds from COSMIC split up into multilayer clouds in the radiosonde results, which leads to the great differences between them.