Characteristics of Precipitation Based on Cloud Brightness Temperatures and Storm Tops in Summer Tibetan Plateau
FU Yunfei;PAN Xiao;LIU Guosheng;LI Rui;ZHONG Lei;School of Earth and Apace Sciences, University of Science and Technology of China;
Characteristics of precipitation types are investigated in summer over the Tibetan Plateau based on the merged 2A25 and 1B01 datasets issued by TRMM(Tropical Rainfall Measuring Mission). The statistics show that many more stratiform precipitation samples are included in 2A25, version 7, in summer over the Tibetan Plateau, and their ratio reaches 85%. In the definition of precipitation types based upon the cloud top brightness temperature(i.e., cloud phases) observed by the thermal infrared channel of VIRS(Visible and Infrared Scanner), results indicate about 43% and 56% of precipitation with ice, mixed ice and water in the top precipitating clouds, respectively, in summer over the Tibetan Plateau. This compares to versus about 77%, 22% and 1% for deep weak convective precipitation, shallow precipitation, and deep strong convective precipitation, respectively, according to storm top classification. The spatial distribution indicates that the frequency and rain intensity of precipitation with ice or mixed ice and water in the top of precipitating clouds increases from the western plateau towards the eastern and southeastern plateau. However, the storm top altitudes for these precipitating clouds decrease from the western and central plateau towards the eastern plateau. In the category of precipitation types defined by storm top altitudes, their spatial distributions show that the frequency of the deep strong convective and shallow precipitation increases from the western plateau towards the eastern plateau, while the frequency of the deep weak convective precipitation shows that it is less in the western and northern plateau, opposite to that in the southern plateau where it is usually one time higher than that in the northern plateau. The spatial distribution of rainfall intensity for both deep weak convective precipitation and shallow precipitation also displays an increasing trend from the western and central plateau towards the eastern plateau, with the opposite variation of storm top altitudes for both precipitation types. In conclusion, the variation in the frequency and intensity of precipitation in summer over the Tibetan Plateau increases from the western to the eastern plateau, contrary to the altitude variation of cloud top and storm top.
【Fund】： 国家自然科学基金项目41230419、91337213、40730950、40375018;; 公益性行业(气象)科研专项GYHY201306077~~
【CateGory Index】： P426.6
【CateGory Index】： P426.6