第七届青年地学论坛

This study investigates the recent changes in precipitation over the southern slope of the Tibetan Plateau (SSTP). Analysis of multi-source precipitation datasets indicates that a significant drying tendency appears over the SSTP area in summer, especially in July, August, and September, with a nearly 20% decline of climatological precipitation during the period of 1980–2018. A moisture budget analysis shows that the drying trend is dominated by a decreased vertical moisture advection due to weakened upward motion, which is resulted directly from the northward shift of the subtropical westerly jet (WJ) over the northern plateau, through weakened upper-tropospheric divergence over the SSTP. Moreover, the meridional shift of the WJ is remotely forced by the internal change in mid-latitude atmospheric circulation showing a circumglobal teleconnection (CGT)-like pattern, by which an anticyclonic trend along the WJ axis appears over the northeastern plateau. Therefore, it is concluded that the long-term CGT-like trend of the mid-latitude atmospheric circulation plays an important role in triggering the drying tendency over the SSTP in the recent decades, through creating a northward shift of WJ and then weakening the upward motion.
 

Dring trend, Tibetan Plateau, Southern slope, Mid-latitude atmospheric changes