Contribution of Changes in Atmospheric Circulation Patterns to Regional Temperature Variation in the Central and Eastern Tibetan Plateau

The Tibetan Plateau is the highest and largest plateau in the world. Its dynamic and thermal effects have significant impacts on both of the regional and global climate change and it is also sensitive to the climate change. Under the background of global warming, there was an obvious trend of climatic warming in the Tibetan Plateau in recent decades. A large number of synoptic climatological analyses have shown that the surface climate variations and large-scale atmospheric circulation are strongly coupled. The study on the relationship between climate change and synoptic-scale atmospheric circulation variation in the Tibetan Plateau is conducive to further understanding the mechanism affecting regional or local climate change, and can also provide a basis for the weather forecast and the construction of statistical downscaling models. In this study, Rotated Orthogonal Functions (REOF) is used to analyze the spatial characters of daily mean temperature variation in the central and eastern Tibetan Plateau (CETP) and a circulation classification method, Simulated annealing and diversified randomization clustering (SAN), is used to analyze the atmospheric circulation variation over Asia, and to discuss the contribution of large-scale atmospheric circulation variation to the temperature change in CETP. The results shown that CETP can be divided into four temperature subregions, including the northern region of the Tibetan Plateau with the southern boundary at 35˚N, the southern region between the Tanggula Mountains and the Himalayan Mountains, the southeastern region of the Tibetan Plateau mainly consisting of Hengduan Mountains area and the central Tibetan Plateau between 31˚N and 35˚N. The relationship between temperature and circulation level revealed that the temperature variations of CETP have a high correlation with the geopotential height variation near the tropopause and thermodynamic contributor to the CETP temperature variations. The dynamic contribution is small, while the effect of the atmospheric circulation pattern on the variation of temperature variation of CETP performs through a dynamic role that supports or blocks the southward advection of cold air.