Analysis on the characteristic of precipitation structure on the eastern slope of the Qinghai-Tibet Plateau based on TRMM PR data

Abstract

Using the TRMM data and ERA5 reanalysis data, a heavy precipitation case in the eastern slope of the Qinghai-Tibet Plateau on July 6, 2006 was investigated. Based on the investigations, the precipitation structure characteristics in summer (June-August) over the eastern slope of the Qinghai-Tibet Plateau were analyzed. Results indicate that the heavy rain case on the eastern slope of the Qinghai-Tibet Plateau occurred in the typical circulation with convergence at the lower level and divergence at the upper level. The rain belt extends from northeast to southwest with the maximum rain rate over 20 mm·h-1. The echo top height of convective precipitation is more than 17 km while the echo top height of stratiform precipitation is no more than 15 km. There exists bright band structure at 6.5 km which is similar to the vertical structure of the stratiform precipitation on the non-plateau region. The statistical analysis shows that the summer precipitation frequency on the south-eastern Qinghai-Tibet Plateau and the connection area between eastern plateau and southern Sichuan Basin are high. In contrast, the frequency of the stratiform and convective precipitation are low on the north-eastern plateau and Sichuan Basin. The summer daily average precipitation shows similarity with precipitation frequency for the years. The characteristics of vertical structure of precipitation radar reflectivity factor are different in the various area. The vertical structures of precipitation radar reflectivity in the south-eastern and north-eastern regions of the Qinghai-Tibet Plateau are similar, but the vertical precipitation structures are different in the non-plateau regions because of the compression induced by the height of the topography. It is also found that there are some similarities between the vertical structure of precipitation in the connection area between eastern plateau and southern Sichuan Basin, the plateau and non-plateau regions. The vertical structure of convective precipitation in the Sichuan Basin, eastern China and tropical and sub-tropical ocean are mostly alike. The same conclusion can be found in the stratiform precipitation except for the height of the bright band is 1 km higher in the Sichuan Basin.

Keywords

• the eastern slope of qinghai-tibetan plateau
• steep terrain
• trmm
• precipitation radar
• precipitation structure