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A surface layer variance heat budget for ENSO
Author(s) -
Boucharel Julien,
Timmermann Axel,
Santoso Agus,
England Matthew H.,
Jin FeiFei,
Balmaseda Magdalena A.
Publication year - 2015
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 - 10.1002/2015gl063843
Subject(s) - thermocline , climatology , el niño southern oscillation , sea surface temperature , amplitude , environmental science , ocean heat content , climate model , multivariate enso index , forcing (mathematics) , atmospheric sciences , geology , climate change , southern oscillation , oceanography , physics , quantum mechanics
Characteristics of the El Niño–Southern Oscillation (ENSO), such as frequency, propagation, spatial extent, and amplitude, strongly depend on the climatological background state of the tropical Pacific. Multidecadal changes in the ocean mean state are hence likely to modulate ENSO properties. To better link background state variations with low‐frequency amplitude changes of ENSO, we develop a diagnostic framework that determines locally the contributions of different physical feedback terms on the ocean surface temperature variance. Our analysis shows that multidecadal changes of ENSO variance originate from the delicate balance between the background‐state‐dependent positive thermocline feedback and the atmospheric damping of sea surface temperatures anomalies. The role of higher‐order processes and atmospheric and oceanic nonlinearities is also discussed. The diagnostic tool developed here can be easily applied to other tropical ocean areas and climate phenomena.