Analysis of Vertical Structure of Clouds in East Asia with CloudSat Data
东亚地区云垂直结构的CloudSat卫星观测研究

Statistical characteristics of the vertical structure of clouds over East Asia are obtained by dividing the area into six regions and analyzing the 2007, 2008, and 2009 datasets from the cloud observing satellite CloudSat and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO). Results indicate that the total cloud amount exhibits a distinct tendency of seasonal change at various altitudes, reaching a maximum in summer and minimum in winter. The maximum value of single-layer cloud amount appears in winter above the ocean and in summer above land. The frequency of occurrence of single-layer clouds in East Asia is 52.2%, 48.1%, 49.2%, and 51.9% for spring, summer, autumn, and winter, respectively; that for multilayer clouds is 24.2%, 31.0%, 19.7%, and 15.8%, respectively. For all six regions, the frequency of occurrence for both types of clouds is highest in summer and lowest in winter. In all four seasons, cloud frequency in the southern region of East Asia is higher than that in the northern region and is greater above the ocean than that above land. These results indicate that variance in the frequency of occurrence for total clouds is decided by that of multilayer clouds. Cloud top height of the highest cloud layer in East Asia reaches a maximum in summer and minimum in winter at 15.1 km and 8.2 km, respectively. The difference in levels is higher in the southern region above the ocean than in the northern region above land at 15.1 km and 12.1 km, respectively. In addition, the thickness of the cloud layer ranges from 1 km-3 km and is largest in summer and smallest in winter; little difference appears among the regions. Moreover, when the number of cloud layers in the multilayer cloud system increases, the mean cloud thickness decreases, and the mean thickness of the higher cloud layer is larger than that of the lower. The intervals among cloud layers show single peak distribution with the peak value appearing between 1 km and 3 km; differences among regions and seasons are minimal. This work supplies useful information for accurate parameterization of vertical cloud structures.