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CMIP3 & CMIP5 Climate Models: Still Trying to Get Things Right

Paper Reviewed
Wang, G., Dommenget, D. and Frauen, C. 2015. An evaluation of the CMIP3 and CMIP5 simulations in their skill of simulating the spatial structure of SST variability. Climate Dynamics 44: 95-114.

In this particular study, the goal of Wang et al. (2015) was merely, as they put it, "to evaluate the CMIP models' skill in simulating the natural internal spatial structure of sea surface temperature (SST) variability in all major ocean basins." And what did they learn from this exercise?

The three Australian researchers report that (1) "most models show substantial deviations from the observations and [2] from each other in most domains," that (3) "the CMIP models tend to largely overestimate the effective spatial number [of] degrees of freedom," that (4) the models "simulate too strongly localized patterns of SST variability at [5] the wrong locations with [6] structures that are different from the observed," and that (7) "the mismatch between the models is as big as the mismatch with the observations."

This spate of problems, as they continue, can (8) "be easily found in fully coupled GCMs as the atmospheric, oceanic and coupling processes could all introduce errors and even amplify the errors from each other," citing the studies of Delecluse et al. (1998), Grenier et al. (2000), Cai et al. (2011) and Gupta et al. (2013). And they thus remind us that (9) "current state-of-the-art CGCMs do not resolve oceanic meso-scale dynamics.

Cai, W., Sullivan, A., Cowan, T., Ribbe and Shi, G. 2011. Simulation of the Indian Ocean dipole: A relevant criterion for selecting models for climate projections. Geophysical Research Letters 38: 10.1029/2010GL046242.

Delecluse, P., Davey, M.K., Kitamura, Y., Philander, S.G.H., Suarez, M. and Bengtsson, L. 1998. Coupled general circulation modeling of the tropical Pacific. Journal of Geophysical Research 103: 14,357-14,373.

Grenier, H., Le Treut, H. and Fichefet, T. 2000. Ocean-atmosphere interactions and climate drift in a coupled general circulation model. Climate Dynamics 16: 701-717.

Gupta, A.S., Jourdain, N.C., Brown, J.N. and Monselesan, D. 2013. Climate drift in the CMIP5 models. Journal of Climate 26: 8597-8615.

Posted 11 May 2015