This study evaluates the interdecadal variability of ENSO in 21 IPCC AR4 CGCMs. 110 years of the Climate of the 20th Century (20C3M) simulations are analyzed using wavelet analysis. The results show that the state-of-the-art CGCMs display a wide range of skill in simulating the interdecadal variability of ENSO. The 22 models can be categorized into three groups. The first group (8 models) shows an oscillation with a constant period shorter than the observed ENSO period, and sometimes with a constant amplitude. The second group (6 models) does not produce many statistically significant peaks in the ENSO frequency band, but usually produces one or two prominent peaks (episodes) at period longer than 6 years. The third group (8 models) displays significant interdecadal variability of ENSO in both amplitude and period. Moreover, the MPI model even reproduces the observed eastward shift of the westerly anomalies in the low-frequency regime.

Full Article: http://www.cdc.noaa.gov/people/jialin.lin/publication.html

Last Updated: 2007-07-25