中文摘要：

利用2008年1月到2009年12月的L波段探空资料，和与之时空匹配的Clouds云观测资料，首先分析了云内和云外相对湿度的累积频率分布，发现以75％作为相对湿度阈值判断云准确率可达81％。随后利用BS（BiasScore）和TS（Thre Score）评分方法，对不同相对湿度阈值进行评分分析，发现以81％作为相对湿度阈值TS评分可达0．66，为最高。接着利用BS和TS评分方法分不同高度对相对湿度阈值进行评分分析，发现随高度的增加该高度上具有最好TS评分的相对湿度阈值在减小。利用这些阈值对云判断时，总的TS评分高于0．6，且其准确率达到84％以上，比利用单一相对湿度阈值判断云准确率要高。最后对这些阈值进行优化，得到一套适合于我国L波段探空秒数据的云垂直结构的判别方法。

英文摘要：

L-band sounding data recorded from January 2008 to December 2009 and responding spatial and temporal Cloudsat data are used to analyze the cumulative frequency distributions of relative humidity in and near clouds. It is determined that the accuracy of cloud discrimination can reach 81% by setting the relative humidity threshold at 75%. In addition, various thresholds of relative humidity for discriminating clouds are evaluated on the bases of bias score （BS） and threat score （TS）. By setting the relative humidity at 81%, the highest TS score of 0.66 is achieved. Moreover, relative humidity thresholds at various heights are also analyzed on the bases of BS and TS. The results show that the relative humidity threshold with the highest TS score among thresholds at the same cloud height decreases when the height increases. The TS score of the discriminate cloud area at these thresholds at responding altitudes is higher than 0.6, and the accuracy is more than 84%, which is significantly better result than that obtained by using a single relative humiditythreshold for all heights. Finally, after optimizing these thresholds, a method of discriminating the cloud vertical structure is proposed by using L-band sounding data.