Regional differences of convection structure of thunderclouds over the Tibetan Plateau

Abstract

Tibetan Plateau (TP) is the highest plateau in the world, and also the source region of several major rivers and supports more than a billion people downstream. Thunderclouds are severe convective synoptic processes and significant contributor to the rainfall over the TP. To better estimate the impact of thundercloud on the hydrological cycle and climatic system, it is necessary to understand the cloud structure and regional variation of thunderstorms over the TP. By using 17-years data of precipitation radar and lightning observations from TRMM satellite, the convective structure of thundercloud over the TP are investigated. Significant differences of thunderclouds in terms of seasonal variation, and convective intensity and structure, are found in eastern, central and western regions of the Plateau (namely ETP, CTP and WTP). From west to east, thundercloud increases in size and intensity. As indicators of thunderstorm intensity, flash rate, ice content, cloud top height and volume convective precipitation rate are all the largest in the ETP, while the average thundercloud frequency is the highest in the CTP. Thunderclouds in different seasons have different capacity of producing lightning with that in June over the ETP being the strongest. In terms of convective structure, the depth and horizontal areas of 20, 30 and 40 dBZ radar echo are the largest over the ETP, and the smallest over the WTP. Although the depth of 40 dBZ echo shows obvious difference among the three subregions, the most remarkable difference among the three subregions is the horizontal area of 40 dBZ radar echo, the value of which over the ETP is about 2.6 times that over the CTP and 4.7 times that over the WTP, respectively.