The El Niño and Southern Oscillation in the historical centennial integrations of the new generation of climate models
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In this study, we compare the simulation of El Niño and the Southern Oscillation (ENSO) in the historical integrations of 17 Coupled Model Intercomparison Project 5 (CMIP5) models with corresponding observations. The mean state and ENSO variations are analyzed in both the atmosphere and ocean and it is found that most of the CMIP5 models exhibit cold (warm) biases in the equatorial (subtropical eastern) Pacific Ocean sea surface temperature that are reminiscent of the split intertropical convergence zone phenomenon found in previous studies. There is, however, a major improvement in the representation of the power spectrum of the Niño3.4 sea surface temperature variations, which shows that, as in the observations, a majority of the models display a spectral peak in the 2–7 year range, have a near-linear relationship with the displacement of the equatorial thermocline and exhibit a robust atmospheric response to ENSO variations. Several issues remain such as erroneous amplitudes in the Niño3.4 sea surface temperature spectrum’s peak and a width of the spectral peak that is either too broad or too narrow. It is also seen that most CMIP5 models unlike the observations extend the ENSO variations in the equatorial Pacific too far westward beyond the dateline and there is very little asymmetry in event duration between the warm and cold phases. ENSO variability forces a dominant mode of rainfall variability in the southeastern United States, especially in the boreal winter season. The CMIP5 exhibited a wide range of response in this metric with several displaying weak to nonexistent, some showing relatively strong, and one indicating excessively zonally symmetric teleconnection over the southeastern United States.
KeywordsENSO CMIP5 El Niño Southern Oscillation Ocean–atmosphere interaction Climate Variability
We acknowledge the World Climate Research Programme’s Working Group on Coupled Modelling, which is responsible for CMIP, and the climate modeling groups (listed in Table 1.1 of this paper) for producing and making available their model output. This work was supported by the grants from NOAA (NA12OAR4310078, NA10OAR4310215, NA11OAR4310110), USGS (06HQGR0125), and USDA (027865).
- Behringer D, Xue Y (2004) Evaluation of the global ocean data assimilation system at NCEP: the Pacific Ocean. Eighth Symposium on Integrated Observing and Assimilation Systems for Atmosphere, Oceans, and Land Surface. AMS 84th Annual Meeting, Seattle, WA, 11–15Google Scholar
- Clarke A (2008) An introduction to the dynamics of El Niño and the Southern Oscillation. Academic press, p 324Google Scholar
- Guilyardi E, Bellenger H, Collins M, Ferrett S, Cai W, Wittenberg A (2012) A First look at ENSO in CMIP5. Clivar Exchange 59(17):29–32Google Scholar
- Kalnay E, Kanamitsu M, Kistler R, Collins W, Deaven D et al. (1996) The NCEP/NCAR 40-year reanalysis project. Bull Amer Soc 77:437–471Google Scholar
- Mechoso CR et al (1995) The seasonal cycle over the tropical Pacific in coupled ocean–atmosphere general circulation models. Mon Wea Rev 123:2825–2838Google Scholar
- Misra V, DiNapoli SM (2012) Understanding wet season variations over Florida. Clim Dyn 34 doi: 10.1007/s00382-012-1382-4
- NRC (2010) Assessment of intraseasonal to interannual climate prediction and predictability. The National Academies PressGoogle Scholar
- Philander SG (1990) El Niño, La Niña, and the Southern Oscillation, International Geophysical Series, Vol. 46. Academic Press, pp 293Google Scholar
- Solomon S et al (2007) Global climate projections. Cambridge University Press, Cambridge, UKGoogle Scholar