Abstract:
Based on the CloudSat 2BCLDCLASS data from July 2006 to April 2009, the geographic distribution and seasonal characteristics of cloud amounts and the cloud vertical structure (CVS) for the particular cloud types over China and its neighborhood were analyzed. Also analyses of the CVS over 8 regions of China and its neighborhood were performed respectively. The results show that cloud amounts of different cloud types vary with territories and seasons apparently. The mean height and thickness of cirrus, altostratus and altocumulus clouds over the areas of the Tibetan Plateau and the Pamir Plateau are smaller than those over other areas. The cloud base height of deep convective cloud appears to be higher over lands, and there are higher average top heights of deep convective clouds in the tropics and subtropics than in the midlatitude. For all cloud types except for cumulus, stratocumulus and nimbostratus, the mean thicknesses are larger over the south of China than those over the north. From the analysis of seasonal variation of cloud heights, we find that the cloud top heights of all cloud types except for stratocumulus have remarkable seasonal variation, and the cloud base heights of low clouds almost do not vary with territories and seasons. However, the cloud base heights of middle and high clouds appear to have obvious season variation over all regions except for the Indian Ocean monsoons zone, the South China Sea and the western Pacific. In any regions and seasons, the average thickness of deep convective clouds is the thickest and that of stratocumulus is the thinnest. The occurrence frequencies of cloud types at different heights vary with areas. As far as the simultaneous occurrence of different cloud types is concerned, cirrus and altocumulus tend to occur together, especially in summer, but nimbostratus and deep convective clouds do not. In deed, nimbostratus and deep convective clouds show a tendency to be somewhat mutually exclusive. Moreover, the statistics and analysis data on the homogeneity of cloud horizontal boundaries show that the cloud base heights of low clouds are more homogeneous than that of middle and high clouds, and cloud base heights of all cloud types except for cirrus and altocumulus whose cloud top and bottom homogeneities are comparable, are more homogeneous than cloud top heights.