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Simulating the MJO and Convectively Coupled Equatorial Waves

Reference
Hung, M.-P., Lin, J.-L., Wang, W., Kim, D., Shinoda, T. and Weaver, S.J. 2013. MJO and convectively coupled equatorial waves simulated by CMIP5 climate models. Journal of Climate 26: 6185-6214.
Hung et al. (2013) state that the purpose of their work was to evaluate "the simulation of the Madden-Julian oscillation (MJO) and convectively coupled equatorial waves (CCEWs) in 20 models from the Coupled Model Intercomparison Project (CMIP) phase 5 (CMIP5) in the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report (AR5) and compares the results with the simulation of CMIP phase 3 (CMIP3) models in the IPCC Fourth Assessment Report (AR4)." Such a comparison would shed some light with respect to how well the models are progressing toward reality.

Although Hung et al. report that their results show that "the CMIP5 models exhibit an overall improvement over the CMIP3 models in the simulation of tropical intra-seasonal variability, especially the MJO and several CCEWs," they concede that (1) "the phase speeds of the model MJO tend to be too slow and the period is longer than observations as part of an over-reddened spectrum, which in turn is associated with too strong persistence of equatorial precipitation," that (2) "the persistence of precipitation in many CMIP5 models is still larger than observations, which is also reflected by the too red precipitation and space-time spectra," and that (3) "only one of the 20 models is able to simulate a realistic eastward propagation of the MJO."

Archived 4 December 2013