The relative contributions of Sea surface temperature and Plateau surface sensible heat flux to China’s interdecadal summer precipitation

Sea surface temperatures (SST) in the Atlantic and Pacific Oceans and surface sensible heat flux (SH) over Asian plateaus, including the Tibetan Plateau (TP), Iranian Plateau (IP), and Mongolian Plateau (MP), underwent abrupt shifts in the late 1990s, significantly influencing China’s rainfall variability. A Statistical method is used to examined the relative contributions of these two factors, revealing that land conditions (plateau SH) contribute slightly more, but are nearly equal to the contributions from ocean conditions (SST). The results suggest anomalous SH heating over the MP leads to significant atmospheric warming, while the weakened SH over the TP and strengthened SH over the IP alter the local atmospheric circulation (i.e. South Asian High). These thermal forcings trigger an anomalous anticyclone over the MP and northeastern China, strengthen the teleconnection pattern across Eurasia, and simultaneously modulate the westerlies and the Asian summer monsoon systems, thereby influencing summer precipitation in China. Furthermore, we use the Community Earth System Model to further verify these results. This study provides new insights into the role of land forcing and ocean forcing on the interdecadal variability of China’s summer rainfall and offers important evidence for understanding the mechanisms through which external climate forcings affect China’s precipitation patterns.