This study investigated the impacts of Tibetan Plateau vertical heating (TPVH) on the Asian summer monsoon (ASM) on the interdecadal scale since the beginning of the 20th century. The ASM, corresponding to TPVH, generally enhances on the interdecadal scale. In the upper troposphere, the upper-level westerly and easterly jet streams shift northwards in Asia, with two meridional "southern low and northern high" wave-like patterns dominating in East Asia and India, respectively. In the lower troposphere, the summer monsoonal airflow and convergence zone migrate northwards in Asia, and two meridional "southern high and northern low" patterns appear in East Asia and India, respectively. Thus, TPVH can strengthen the baroclinicity over northern East Asia and northern India, but weaken it over southern East Asia and southern India. Moreover, two anomalous meridional circulation cells are identified in East Asia and India, with ascending branches in their northern parts and descending branches in their southern parts. Eventually, the ASM strengthens, leading to a southern dry and northern wet pattern in East Asia and India.

Although influences of the Atlantic multidecadal variability (AMV) and atmospheric heat source over the Tibetan Plateau (TPHS) on the East Asian summer rainfall (EASR) have been previously investigated, the relationship between the AMV and TPHS, and their synergistic impact on the EASR are still unclear. We investigate the distinct relationship between the AMV and TPHS, and the role of Tibetan Plateau (TP) in the impact of AMV on the EASR in this study. Results show that the AMV exerts a remote effect on the EASR through an atmospheric teleconnection, and the TP serves as a booster of this remote effect. The warming of the North Atlantic (positive phase of AMV) enhances the Asian summer monsoon through a zonal wave train along the northern mid-latitudes, yielding an anomalous tripole rainfall pattern over East Asia. The enhanced warm and moist monsoon airflow converges and climbs up along the southern and eastern flanks of the TP, resulting in stronger latent heating over the TP than over other regions along the same latitude due to the orographic effect of the huge plateau. The enhanced TPHS in turn further strengthens the summer monsoon and the East Asian tripole rainfall pattern by exciting a downstream meridional wave train. When the AMV and TPHS are in-phase, the zonal wave train originating from the North Atlantic is strong and propagates eastward to the Asia–Pacific regions, significantly regulating the East Asian summer monsoon. Notably, the TP boosts this remote impact of the AMV through the effect of superimposition.

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