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Modelling the Arabian Sea SST Evolution from Spring to Summer

Paper Reviewed
Sayantani, O., Gnanaseelan, C., Chowdary, J.S., Parekh, A. and Rahul, S. 2016. Arabian Sea SST evolution during spring to summer transition period and the associated processes in coupled climate models. International Journal of Climatology 36: 2541-2554.

In this intriguing study, Sayantani et al. (2016) examined the sea surface temperature (SST) evolution during the spring-to-summer transition months of May and June over the Arabian Sea (AS) region in historical simulations of 13 CMIP5 models and the Climate Forecasting System coupled models CFSv1 and CFSv2. And what did they learn by so doing?

The five researchers from the Indian Institute of Tropical Meteorology in Pune, India, report that (1) "the annual cycle of SST shows that the summer monsoon cooling is not adequately captured by many models," that (2) "the monsoon low-level jet (LLJ) is not accurately represented in most of the models," that (3) "the misrepresentation of the LLJ causes bias in the oceanic processes, leading to [4] unrealistic SST evolution in many models," and that (5) "the model deficiency in representing AS SST is speculated to be a major limiting factor in capturing the monsoon rainfall in the current coupled models."

In addition, Sayantani et al. state that (6) "the south-westerly winds during summer monsoon are not captured well by many models," that (7) "the core of LLJ is located north of the normal position in most of the models," that (8) "such wrong representation of monsoon winds can lead to biases in the oceanic processes and in turn [9] misrepresent SST," with the result that (10) "the discrepancy in SST evolution in the coupled models may cause strong biases in precipitation over the ISM [Indian Summer Monsoon] region."

Posted 21 September 2016