Abstract:Based on the CloudSat 2B CLDCLASS LIDAR data from January 2007 to December 2008, the occurrence frequency, mean height, and thickness of different types of clouds in the single layer and multi layer cloud systems over North China are analyzed. The results show that the occurrence frequencies of single layer and multi layer clouds have a distinct seasonal variation, with maximum in summer and minimum in winter. The frequency of single layer clouds is far greater than that of multi layer clouds, 443%, 461%, 378%, and 328% for spring, summer, autumn, and winter, respectively. Two layer clouds account for the largest proportion in the multi layer cloud system. The analysis of average cloud height and thickness of different layers shows that the height of upper level three layer clouds is the greatest, and the height of lower level three layer clouds is the least; the thickness of single layer clouds is significantly greater than those of multi layer clouds; furthermore, the mean thickness of cloud layers decreases with increasing total number of layers of clouds. The analysis of the occurrence frequencies of different types of clouds shows that cirrus appears mostly in single layer clouds, as well as in middle and upper level multi layer clouds; altostratus and altocumulus account for a certain proportion of single layer clouds and multi layer clouds at various levels; stratus appears mostly in lower level multi layer clouds; and stratocumulus, cumulus, and deep convective clouds mainly appear in single layer clouds and lower level multi layer clouds; nimbostratus mainly appears in single layer clouds in summer. For cirrus, altostratus, and altocumulus, the mean height and thickness have significant differences in different cloud systems.