Variations in sensible heat flux of High-Asia and their relationship with China's summer precipitation

The High-Asia (HA), which includes the Tibetan Plateau (TP), Iranian Plateau (IP) and Mongolian Plateau (MP), is experiencing a warming rate that is twice the global average. The increasing temperature is causing significant changes in thermal conditions across the HA and surrounding regions, which may further affect China's summer precipitation. This study used datasets from the ERA5-Land reanalysis and the high-resolution China Meteorological Forcing Data to investigate variations in SH over three plateaus of HA, and to explore the relationship between these variations and changes in China's summer precipitation. The results indicate that variations in summer SH of the HA are the largest, making them the primary contributor to the annual mean values. The summer SH over TP exhibited a decreasing trend from 1979 to 2021 (-0.47 W m-2 decadal-1, p<0.05), in contrast with the trends in IP and MP (0.59 and 1.46 W m-2 decadal-1, respectively, p<0.05). Additionally, based on the empirical orthogonal unfolding method, the dominant SH pattern over the HA revealed that the variation over the TP was opposite to that over IP and MP, and this pattern experienced a significant interdecadal shift in 1999. Moreover, The initial leading temporal expansion series of singular value decomposition showed a consistent trend in SH over the HA and summer precipitation in China (correlation coefficient=0.85, p<0.05), and an abrupt change was observed during 1998-1999. The dominant spatial pattern demonstrated that interdecadal drought in the northeast China and the Yangtze River valley exhibited a significantly positive correlation with the leading SH pattern over the HA. Conversely, increased precipitation in the northwest and south of China showed a negative correlation. Our study suggests a link between SH over HA and China's summer precipitation, providing new insights into understanding the mechanisms underlying changes in China's summer precipitation.