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Abstract

The North Atlantic sea surface temperature multidecadal oscillation, or AMO, has a substantial impact on both the global and local climate. The authors suggest a delayed oscillator model of interdecadal sea-air coupling to describe the underlying physical principles of AMO. On the basis of the impact of cumulative atmospheric forcing on ocean circulation, they also develop new AMOC indicators and shed light on the AMO's dynamics. To explain the remote impacts of AMO, the authors propose and identify the Atlantic-West Pacific trans-basin SST mode as a significant mode of global inter-oceanic interdecadal variability based on observational and model evidence. They discover that this mode started to change from a negative to a positive phase in the 1990s, which led to significant changes in the regional SST system in the Indian Ocean and the Arabian Sea. As a result, the warming rate of the Arabian Sea began to significantly accelerate in the 1990s. The Atlantic-West Pacific trans-basin SST mode corresponds to the synchronous changes of the Atlantic warm pool and the West Pacific warm pool, which have an important impact on the zonal Walker circulation; on the other hand, the Atlantic-West Pacific trans-basin SST mode can modulate the SST gradient in the northern and southern hemispheres, causing the variability of the meridional Hadley circulation and the north-south shift of the ITCZ position. These AMO-related changes have an impact on the climate in Asia as well as extreme weather (such tropical cyclones and heatwaves).