Association between Tibetan Heat Sources and Heat Waves in China.

The Tibetan Plateau (TP), known as the "Third Pole," profoundly affects weather and climate at regional and global scales. In this study, we investigate the characteristics of heat waves in China and their association with the TP heat source. The results show that during the summertime from 1980 to 2020, the frequency of heat wave days that hit eastern China and northwest China increased at rates of 0.09 and 0.24 days yr−1, respectively, accompanied by an increase in the atmospheric heat source (AHS) over the TP by over 2 W m−2 yr−1 under the background of global warming. The enhanced TP heat source induces an anomalous upper-tropospheric anticyclone, which caused the western Pacific subtropical high and South Asia high to be stronger and closer to each other, causing descending motions over eastern China and consequently more heat waves. At the same time, the enhanced TP heat source weakened the westerlies, thereby favoring the occurrence and maintenance of the anticyclone centered in northwest China and creating more heat waves due to strong descending motions. Therefore, the association between the TP heat source and heat waves in China provides relevant information for studying the mechanism and future changes of heat waves. Significance Statement: The Tibetan Plateau significantly affects the surrounding weather and climate. We find that there are some linkages between the Tibetan heat source and heat waves in China. The stronger the Tibetan heat source is, the more heat waves hit China. The enhancement of the Tibetan heat source could induce an anomalous upper-tropospheric anticyclone by affecting the western Pacific subtropical high and South Asia high, consequently causing descending motions over eastern China and the resulting heat waves. The weaker westerly due to the enhanced Tibetan heat source favors the occurrence of the anticyclone centered in northwest China, leading to more heat waves by descending motions. This study reveals a potential contributor to heat waves in China, providing some clues for better prediction in the future. [ABSTRACT FROM AUTHOR]