Abstract
The future change in the El Niño-Southern Oscillation (ENSO) influence on regional climate has important implications for socio-economic activities, but is subject to considerable uncertainties, one of which stems from the uncertainty in the tropical sea surface temperature (SST) warming pattern. Here, based on two sets of CMIP6 atmospheric general circulation model (AGCM) simulations and a large ensemble AGCM simulation forced by historical and projected SST, we reveal a prominent modulating effect of the tropical SST warming pattern on the response of East Asian summer precipitation to ENSO during its developing phase. At present, a developing El Niño/La Niña event produces vigorous convective heating anomalies in the tropical western-central Pacific, leading to anomalous cyclonic/anticyclonic circulation over the western North Pacific (WNP) and evident subsidence/ascent over East Asia, thereby reducing/increasing the East Asian summer precipitation. In a future warming climate, an El Niño-like SST warming pattern may increase the meridional gradient of climatological water vapor over East Asia and the sensitivity of the tropical Pacific convective response to ENSO-related SST anomaly. As a result, both the anomalous WNP cyclone/anticyclone and subsidence/ascent are intensified with stronger moisture divergence/convergence over East Asia, leading to even stronger summer precipitation deficit/surplus there. In contrast, the La Niña-like warming pattern has the opposite effect on the future change of atmospheric circulation responses, weakening the ENSO influence on East Asian summer precipitation during the developing phase. Our results have important implications for better understanding the future changes in ENSO’s influence on East Asian climate.
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