Role of the western hemisphere warm pool in climate variability over the western North Pacific
The climate variability in the Western North Pacific (WNP), which is surrounded by densely populated countries, is closely tied to the lives of the people in the East Asia in terms of climate and socioeconomics. Along with global warming, remarkable interannual and interdecadal variations in sea surface temperature (SST) and sea surface height have been observed in the WNP. Here we demonstrated that boreal summer SST variability in the western hemisphere warm pool (WHWP, a.k.a. Atlantic Warm Pool) near the Intra-Americas Sea, which is known as the second largest warm pool on the planet, has considerably contributed to the climate variability in the WNP in subsequent winter. This is possible due to westward propagation of Rossby waves associated with a WHWP-SST warming (cooling) in mid-summer to early fall season, which induces northerly (southerly) wind anomalies over the North Pacific. In the presence of northeasterly mean trade winds, the anomalous meridional winds interact with SST and precipitation anomalies. Such air-sea coupling processes gradually move equatorward and westward along the climatological migration of the Pacific Intertropical Convergence Zone, and it has finally an effect on the climate variability over the WNP in winter. Further diagnosis verifies that WHWP-WNP connection exists not only on interannual time scale but also on decadal time scale. The analysis using state-of-the-art climate models reasonably supports this argument. A better understanding of the WHWP influence is expected to improve forecasts for the WNP climate and assist socioeconomic development in the East Asia.
KeywordsWestern North Pacific Western Hemisphere Warm Pool (Atlantic Warm Pool) Air-Sea Coupling
J.-S. Kug is supported by the Korea Meteorological Administration Research and Development Program under Grant KMI2018-03214, and the National Research Foundation of Korea(NRF) Grant funded by the Korea government(MSIT) (NRF-2018R1A5A1024958). This work was jointly supported by NSFC grant 41630423, NSF grant AGS-1565653, NOAA NA18OAR4310298, and JAMSTEC JIJI project. This is SOEST contribution number 10641, and IPRC contribution number 1360.
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