Abstract:Based on snow depth dataset over China and CN05 gridded precipitation data over China, the relationship between Tibet Plateau (TP) snow depth and the summer precipitation in Yunnan are investigated by using Singular Vector Decomposition (SVD) and correlation analysis. The results show that the positive snow depth anomalies in the central and western TP during winter and spring can enhance summer precipitation in Yunnan, especially in the Jinsha River basin and the southwest of Yunnan, and the correlations between TP snow depth and Yunnan summer precipitation may be independent of the influence of ENSO on summer precipitation in Yunnan. The possible impact mechanism has been investigated through the diagnostic analyses using ERA5 reanalysis datasets, it is suggested that heavier snow depth in the key region of TP lead to the lower surface air temperature in the central and western parts of the TP and nearby areas in spring, which is conducive to the late onset of the South Asian summer monsoon, hence weaker South Asian summer monsoon and the associated monsoon depression, along with the abnormal westerly wind to the south of the TP. Furthermore, colder surface temperature associated with heavier snow depth in the TP can also initiate the wave train at 200 hPa, which will propagate from the western part of the plateau through Mongolia to Northeast Asia along the westerly jet stream, and an anomalous cyclonic circulation could be found in Northeast Asia, which was conducive to the southward movement of the cold air in the middle and high latitudes, leading to more rainfall in Yunnan province. Meanwhile, wave train at the 850 hPa can also be found, which spread from the southwest side of the plateau to the South China Sea, leading to an anomalous anticyclone circulation in South China Sea. The anomalous low level shear over Yunnan will then be developed from the westerly wind on the south side of the plateau and the southwesterly wind on the northwest side of the South China Sea anticyclone, which is favorable for more precipitation in Yunnan. Meanwhile, cold air flows southward to Yunnan and converges with warm and humid air, which also contributes to enhanced summer precipitation in Yunnan.