CLIMATIC FEATURES OF EARLY SPRING RAINS OVER SOUTHEASTERN TIBETAN PLATEAU AND THEIR CAUSES
LI Tian-hang
LIU Xuan-fei
Abstract：Based on TRMM,GHCN and CMAP precipitation observations as well as ERA-Interim reanalysis dataset,we investigated the climatic features of early spring rains (ESR)over southeastern Tibetan Plateau (TP)and their causes.The rain-belt is distributed along the Brahmaputra Valley,covering southeastern Tibet, northwestern Yunnan,northeastern India and northern Burma.It is found by moving-t-test that the rainfall expe-riences significant increasing at the 1 7th pentad,a time that can be regarded as the onset of ESR.The turning from northwesterly to southwesterly wind in the lower level over region (88 ~94 °E,22 ~27 °N)is a symbol for the establishment of ESR.Such a southwesterly wind maintains robust during ESR seasons,leading to conver-gence in wind speed and water vapor and the formation of ESR.Meanwhile,the southwesterly wind will be forced to lift when it blows into the bell terrain which is surrounded by the Himalaya,Transverse,and Naga Mountains,thus forming maximum precipitation centers in the upwind slope.This is the immediate climatic cause of ESR formation.Further study reveals that the southwesterly wind is associated with both the mechanical forcing of TP and sensible heating over central southern TP,suggesting that the presence of TP plays a funda-mental role in the climatic formation of ESR.
Keywords：southeastern Tibetan Plateauearly spring rainsclimatic featuresclimatic causessouthwesterly wind
Publication Date：2016-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：8( 717-724 )