Open AccessModeling the ENSO impact of orbitally induced mean state climate changes
Author(s) -
Salau O. R.,
Schneider B.,
Park W.,
Khon V.,
Latif M.
Publication year - 2012
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2011jc007742
Subject(s) - climatology , sea surface temperature , amplitude , western hemisphere warm pool , el niño southern oscillation , teleconnection , forcing (mathematics) , climate model , holocene , geology , walker circulation , environmental science , pacific decadal oscillation , multivariate enso index , upwelling , oceanography , climate change , physics , southern oscillation , quantum mechanics
The sensitivity of the El Niño–Southern Oscillation (ENSO) phenomenon to changes in the tropical Pacific mean climate is investigated with a coupled atmosphere‐ocean‐sea ice general circulation model (AOGCM), the Kiel Climate Model (KCM). Different mean climate states are generated by changing the orbital forcing that causes a redistribution of solar energy, which was a major driver of both the Holocene and the Eemian climates. We find that the ENSO amplitude is positively correlated with both the Equatorial Pacific sea surface temperature (SST) and the equatorial zonal SST contrast. The latter is controlled by the upwelling‐induced damping of the SST changes in the Eastern Equatorial Pacific (EEP), and by the vertical ocean dynamical heating and zonal heat transport convergence in the Western Equatorial Pacific. The ENSO amplitude also correlates positively with the seasonal SST amplitude in the EEP and negatively with the strength of the easterly Trades over the Equatorial Pacific. However, the ENSO period is rather stable and stays within 3–4 years. Enhanced ENSO amplitude is simulated during the late‐Holocene, in agreement with paleoproxy records. The tight positive correlation (r = 0.89) between the ENSO strength and the Western Pacific Warm Pool (WPWP) SST suggests that the latter may provide an indirect measure of the ENSO amplitude from proxy data that cannot explicitly resolve interannual variability.