Summer Land Surface Thermal Anomalies over Eurasia and Their Relationship with Summer Rainfall in East China

Based on ERA-40 reanalysis, CRU TS3.0 dataset, and observational data, the characteristics of Eurasian land surface thermal anomalies in summer and their relationship with summer rainfall in East China were investigated. The results showed that the large-scale characteristics of Eurasian land surface air temperature and sub-surface soil temperature are basically the same. The leading mode of Empirical Orthogonal Function (EOF) manifests characteristics of reversal change between southwest Eurasia and other regions of the continent and the principal components went through transition in the late 1980s. When a positive summer land surface thermal anomaly happens in North India and central-eastern China, the East Asian summer monsoon tends to be strengthened and the western Pacific subtropical high (WPSH) moves eastward, which benefits stronger southerly winds over East China but less water vapor and weakened ascending motion in the Yangtze-Huaihe River basin, resulting in reduced precipitation over this region. At the same time, more water vapor and intensified ascending motion in the southeast and northeast of China tends to produce more summer precipitation, and vice versa. When a positive summer land surface thermal anomaly occurs in the areas to the east and west of Lake Baikal, but a negative anomaly occurs in northeastern China, the East Asian summer monsoon tends to be strengthened and the WPSH moves westward, which results in less water vapor and weakened ascending motion in the southeast of China and central Inner Mongolia, leading to less precipitation over these regions. Meanwhile, more water vapor and intensified ascending motion are found in the rest of East China, accompanied by more precipitation, and vice versa.