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Impacts of the Tropical Pacific Cold Tongue Mode on ENSO Diversity Under Global Warming
Author(s) -
Li Yang,
Li Jianping,
Zhang Wenjun,
Chen Quanliang,
Feng Juan,
Zheng Fei,
Wang Wei,
Zhou Xin
Publication year - 2017
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
eISSN - 2169-9291
pISSN - 2169-9275
DOI - 10.1002/2017jc013052
Subject(s) - climatology , sea surface temperature , empirical orthogonal functions , el niño southern oscillation , mode (computer interface) , la niña , global warming , oceanography , zonal and meridional , walker circulation , environmental science , tropics , geology , geography , climate change , biology , ecology , computer science , operating system
The causes of ENSO diversity, although being of great interest in recent research, do not have a consistent explanation. This study provides a possible mechanism focused on the background change of the tropical Pacific as a response to global warming. The second empirical orthogonal function mode of the sea surface temperature anomalies (SSTA) in the tropical Pacific, namely the cold tongue mode (CTM), represents the background change of the tropical Pacific under global warming. Using composite analysis with surface observations and subsurface ocean assimilation data sets, we find ENSO spatial structure diversity is closely associated with the CTM. A positive CTM tends to cool the SST in the eastern equatorial Pacific and warm the SST outside, as well as widen (narrow) zonal and meridional scales for El Niño (La Niña), and vice versa. Particularly in the positive CTM phase, the air‐sea action center of El Niño moves west, resembling the spatial pattern of CP‐El Niño. This westward shift of center is related to the weakened Bjerknes feedback (BF) intensity by the CTM. By suppressing the SSTA growth of El Niño in the eastern equatorial Pacific, the CTM contributes to more frequent occurrence of CP‐El Niño under global warming.