Winter extreme precipitation over the Tibetan Plateau influenced by Arctic sea ice on interdecadal timescale

Abstract

The Tibetan Plateau (TP) and the Arctic are the most sensitive regions to global climate change. However, the interdecadal varibility of winter extreme precipitation over the TP and its linkage with Arctic sea ice are still unclear. In this study, the characteristics and mechisnems of the TP extreme precipitation (TPEP) influenced by Arctic sea ice on interdecadal timescale are studied based on the daily precipitation, monthly sea ice concentration and ERA5 reanalysis data from 1980 to 2018. We found that the dominant mode of the TPEP in winter mostly exhibits a uniform spatial variation on the interdecadal timescale, with an opposite weak variation in the southeastern TP, and the Arctic sea ice concentration (SIC) before 2002 are larger than that after 2003. The interdecadal variation of TPEP is affected by two teleconnection wave trains regulated by the Barents and Kara Sea ice. In the light ice years, a remarkable positive geopotential height (HGT) anomaly appears over the Barents‒Kara Sea and a remarkable negative HGT anomaly is located over the Lake Baikal. Two wave trains originating over the Barents‒Kara Sea can be observed. The southern branch forms a wave train through the North Atlantic along the subtropical westerly jet stream, showing a ‘+ − + − +’ pattern of HGT anomalies from Arctic to the TP. Negative HGT anomaly controls the western TP, which creates dynamic and water vapor conditions for the TPEP. The northern branch forms a wave train through the Lake Baikal and the southeast of the TP, showing a ‘+ − +’ HGT anomaly distribution. Positive HGT anomaly controls the southeastern TP, which is not conducive to precipitation in the region. When the SIC in the Barents‒Kara Sea increases, the situation is opposite. The above analysis also reveals the reason for the difference in the east‒west distribution of the TPEP.