Effect of recent Atlantic warming in strengthening Atlantic–Pacific teleconnection on interannual timescale via enhanced connection with the pacific meridional mode
The Atlantic warm pool (AWP), which features the highest sea surface temperature (SST) in the western Hemisphere in boreal summer to early fall, has been known to have a significant influence on the climate in its surrounding regions. It is reported that the AWP has become warmer and warmer, so that AWP–SST during a couple of recent decades has been higher than any other period since the twentieth century. Under the increased mean AWP–SST, atmospheric responses to the anomalous AWP–SST are intensified, which corresponds to a higher possibility of deep convection formation. Through Rossby wave propagation induced by the deep convection, AWP signals are able to reach further west toward the central North Pacific. At this moment, anomalous northerly winds are introduced over the North Pacific, which advects negative moist static energy (MSE) into the subtropics and simultaneously contributes to a SST cooling by interacting with northerly mean trade winds. Owing to the Gill-type response to a negative heating anomaly associated with the anomalous SST cooling and the negative MSE, the anomalous northerly winds are further developed over the North Pacific. Such air–sea coupling persists throughout fall to winter, leading to Pacific meridional mode development in the following spring. Subsequently, the PMM acts to boost El Niño and Southern Oscillation events. Coupled model experiments were carried out to investigate the extent to which the mean AWP–SST warming strengthens the Atlantic–Pacific interbasin teleconnection on interannual timescales, and it is proven to support observational analysis.
KeywordsAtlantic warm pool Pacific meridional mode El Niño
This work was supported by NSFC Grant 41630423, 973 project 2015CB453200, NSF Grant AGS-1565653, NOAA grant NA18OAR4310298, NSFC grant 41875069, and JAMSTEC JIJI Theme 1 project. This is SOEST contribution number 10620, and IPRC contribution number 1355. We would like to thank two anonymous referees for their constructive comments. SWY and HRK were funded by the Korea Meteorological Administration Research and Development Program under grant KMI2018-03211.
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