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Biases in CMIP3 and 5 Simulations of the Indian Ocean Basin Mode

Paper Reviewed
Tao, W., Huang, G., Hu, K., Gong, H., Wen, G. and Liu, L. 2016. A study of biases in simulation of the Indian Ocean basin mode and its capacitor effect in CMIP3/CMIP5 models. Climate Dynamics 46: 205-226.

Introducing their work, Tao et al. (2016) describe how they employed 30-year simulations of the Indian Ocean Basin Mode (IOBM) covering the period 1970-2000, which they obtained from 15 CMIP3 models and 32 CMIP5 models, hoping they would see some improvements in the CMIP5 model results over those of the CMIP3 models. And what did they find when all was said and done?

The six Chinese scientists report that during some parts of the year CMIP5 models show "some improvement" when "compared with CMIP3 models," although they also say "there are no remarkable changes." And they further state that "the spread of inter-model biases also shows improvement from CMIP3 to CMIP5." However, they additionally report that "biases of IOBM simulation are ultimately related to the ENSO simulation," and that "problems about ENSO simulation in state-of-the-art CGCMS still exist," including (1,2) "intensity and westward extension of SST anomalies," as well as (3) "rainfall biases [that] further affect the simulation of the South Indian Ocean anticyclone," plus (4 and counting) many other "oceanic processes."

In concluding, therefore, Tao et al. state that these as-yet-unresolved shortcomings "call for a breakthrough in CGCM [Coupled Ocean-Atmosphere General Circulation Model] simulations of physical processes associated with ENSO."

Posted 29 June 2016