To what extent does ENSO rectify the tropical Pacific mean state?

The role of the El Niño-Southern Oscillation (ENSO) in modulating the mean sea surface temperature (SST) in the tropical eastern Pacific is investigated. A strategy is developed to separate the observational record from 1958 to 2010 into two groups, ENSO and non-ENSO periods. A simple analytical fra...

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Bibliographic Details
Published in:Climate dynamics 2023-10, Vol.61 (7-8), p.3875-3891
Main Authors: Xue, Manrui, Li, Tim
Format: Article
Language:English
Subjects:
Amplitude
Amplitudes
Climatology
Earth and Environmental Science
Earth Sciences
El Nino
El Nino phenomena
El Nino-Southern Oscillation event
Environmental aspects
Geophysics/Geodesy
Heat flux
Heat transfer
Influence
La Nina
Ocean models
Ocean temperature
Oceanography
Sea surface
Sea surface temperature
Southern Oscillation
Surface temperature
Thermoclines (Oceanography)
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Summary:The role of the El Niño-Southern Oscillation (ENSO) in modulating the mean sea surface temperature (SST) in the tropical eastern Pacific is investigated. A strategy is developed to separate the observational record from 1958 to 2010 into two groups, ENSO and non-ENSO periods. A simple analytical framework is constructed to quantitatively delineate the contributions of oceanic dynamic heating (ODH) and surface heat fluxes to rectifying the mean SST. It is found that the differences in the mean SST between the two periods are evident, though minor, despite distinctive interannual SST variabilities. Both linear and nonlinear ODH, as well as surface heat fluxes, contribute to this slight mean SST difference. Idealized oceanic model experiments in the presence and absence of ENSO are conducted. The experiments confirm that ENSO moderately impacts the mean SST in the equatorial eastern Pacific. Although the amplitude of the linear ODH associated with ENSO is large, its impact on the long-term mean SST is small because the sign of its contribution changes between El Niño and La Niña phases. The nonlinear ODH, on the other hand, has the same sign during the warm and cold episodes. However, its accumulated effect on the mean SST is small due to its weak amplitude.
ISSN:0930-7575
1432-0894
DOI:10.1007/s00382-023-06750-6