The Equatorial Cold Tongue Bias in CGCMs: Its Impact on ENSO
Vanniere, B., Guilyardi, E., Madec, G., Doblas-Reyes, F.J. and Woolnough, S. 2013. Using seasonal hindcasts to understand the origin of the equatorial cold tongue bias in CGCMs and its impact on ENSO. Climate Dynamics 40: 963-981.
In attempting to unscramble and resolve these many problems, Vanniere et al. used seasonal re-forecasts or hindcasts to "track back" the origin of the major cold bias, so that "a time sequence of processes involved in the advent of the final mean state errors can then be proposed," applying this strategy to the ENSEMBLES-FP6 project multi-model hindcasts of the last decades."
When all was said and done - and there was really a lot that was said and done - the five researchers discovered that "the models are able to reproduce either El Niño or La Niña close to observations, but not both [itlaics added]." Thus, "more work is needed to understand the origin of the zonal wind bias in models," and they indicate, in this regard, that "understanding the dynamical and thermodynamical mechanisms that drive the tropical atmosphere is required both to alleviate OAGCM errors and to describe the full extent of the atmosphere's role in tropical variability, such as ENSO."
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