Cirrus Cloud Distribution over China from Spaceborne Lidar Observations

The distribution of cirrus clouds over China is presented using the Earthorbiting CloudAerosol Lidar with Orthogonal Polarization (CALIOP) Level 25 km (horizontal resolution) cloud layer product from June 2006 to May 2008. The three quality control standards based on cirrus climatologies can be effectively used to eliminate the cirrus false identifications in this product. From the analysis of cirrus cloud horizontal distribution, the authers attribute the highest occurrence frequency of cirrus clouds of about 60% in the south of China near Intertropical Convergence Zone (ITCZ) to the strongly rising air and rich water vapor. The terraininduced cirrus clouds produced by uplifted relatively warm and moist air on the QinghaiXizang Plateau cause the relatively high occurrence frequency of about 30%－40% on the northeast slope of QinghaiXizang Plateau. The migrations of ITCZ and monsoon induce the seasonal latitudinal movement of cirrus over China, and the relatively high cirrus on the northeast slope of QinghaiXizang Plateau relatively which occurs in winter and spring as well. The latitudinal variation of vertical distribution of cirrus displays that the cirrus clouds at low-latitude center around 16 km due to the limit of tropopause. The analysis shows that the horizontal distribution of multilayered cirrus cloud systems with different kinds of cloud is closely associated with the latitudinal distribution of different kinds of cloud. In addition to the multilayered cirrus cloud systems occurring with cirrus, the relatively high value on the northeast of Qinghai-Xizang Plateau is mainly contributed to the occurrence of systems with high altocumulus.