The Thermal and Mechanical Effects of the Tibetan Plateau on Asian Monsoons

The uplift of the Tibetan Plateau profoundly shapes the Asian summer monsoons1-5, with elevated temperatures over the Plateau widely recognized as a key driver6-9. However, its thermal effect is closely intertwined with the Plateau’s mechanical influence10-13, making their individual contributions difficult to disentangle. Here, we apply a novel atmospheric temperature nudging technique within an atmosphere–ocean coupled climate model to isolate these effects. Our simulations show that the Plateau’s thermal forcing is the primary driver of East Asian monsoon circulation and precipitation, while also contributing 40–50% to the strengthening of South Asian monsoon circulation. Meanwhile, the mechanical effect, strongest along the southeastern flank, generates a downstream low-pressure system and enhances southerly winds over the South China Sea and the Philippine Sea. Further simulations comparing coupled and uncoupled ocean–atmosphere interactions demonstrate that Tibetan Plateau-induced surface cooling in the Arabian Sea strengthens monsoonal southwesterlies by 2 m s⁻¹ and contributes to the eastward shift of South Asian summer monsoon precipitation. These findings reveal the distinct yet interconnected roles of thermal and mechanical forcing, as well as their interactions with sea surface temperatures, providing new insights into the fundamental mechanisms driving monsoon variability.