Holocene multi-centennial variations of the Asian summer monsoon triggered by solar activity

Solar activity affects Asian summer monsoon (ASM) at various time scales. However, it remains unknown if and how solar activity can influence ASM on the centennial time scale. Using the Community Earth System Model, we conduct a solar activity forced Holocene transient simulation with an acceleration factor of 10 and show that during the middle‒late Holocene ASM precipitation exhibits a significant 300‒600-year periodicity under solar forcing. This model-produced multi-centennial variation is also suggested by proxy data. The leading mode of the multi-centennial ASM variation shows a “wet tropics–dry subtropics” pattern, which lags the corresponding solar activity by about a quarter cycle. The western North Pacific (WNP) circulation system is responsible for the multi-centennial ASM variation, through enhancing the climatological south Asia‒WNP monsoon trough. We suggest that solar activity modulates the zonal SST gradients of the tropical Pacific, inducing the anomalous WNP cyclone and enhancing ASM precipitation in a delayed mode.