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Quantifying the Role of Oceanic Feedbacks on ENSO Asymmetry
Author(s) -
Guan Cong,
McPhaden Michael J.,
Wang Fan,
Hu Shijian
Publication year - 2019
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2018gl081332
Subject(s) - thermocline , asymmetry , climatology , el niño southern oscillation , geology , magnitude (astronomy) , oscillation (cell signaling) , atmospheric sciences , physics , chemistry , quantum mechanics , biochemistry , astronomy
The role of oceanic feedbacks in determining the asymmetry of El Niño–Southern Oscillation (ENSO) magnitude, spatial structure, and duration is quantified on the basis of a novel temperature variance budget. Results confirm previous studies that in the eastern Pacific, El Niño warm temperature anomalies are larger in magnitude than La Niña cold temperature anomalies mainly due to stronger positive oceanic feedbacks for El Niño. We find that La Niña cold anomalies are typically stronger than El Niño warm anomalies in the central Pacific with a faster growth rate for cold anomalies, due to a stronger positive thermocline feedback and weaker nonlinear damping. The thermocline feedback related to recharge oscillator dynamics plays a dominate role and leads to asymmetry in the duration of El Niño and La Niña events. In particular, the thermocline feedback becomes significantly negative during the late decaying phase of El Niño and speeds up its demise.