Evaluation of CMIP5 climate model projections for surface wind speed over the Indian Ocean region

Global climate model (GCM) simulations of coupled model inter-comparison project phase 5 are being widely used for projections of the future climate change. The present study systematically evaluated the future simulations performed under four contrasting representative concentration pathway (RCP) scenarios obtained from 35 GCMs. The current wind climate (2006-2016) in GCM simulations have been assessed relative to merged altimetry derived wind speed. Skill assessment of the GCMs in representing the mean variability was investigated in detail using the Taylor's skill score and thereby converging to a suite of best-performing models was selected. Multi-model mean (MMM) corresponding to four RCP scenarios were constructed from ACCESS1.0, CanESM2, CMCC-CMS, HadGEM2-AO, HadGEM2-CC, HadGEM2-ES, MPI-ESM-MR, MIROC-ESM, MRI-CGCM3 and NorESM1-M. The MMM wind climate estimated from these groups of models tend to perform better than individual models with significant improvements seen over most of the Indian Ocean (IO) region. The MMM skill score obtained from the four RCP scenarios were found to be similar, as the radiative forcing in these climate model experiments do not vary significantly for the recent decades. Significant changes in wind climate projections with reference to the historical period (1993-2005) are observed in the northern IO region, the zonal band of 30 degrees S and region south of 40 degrees S. Future projected changes in surface wind are found to be moderate for the 2026-2045 periods and the patterns in wind speed climate would be significantly changed by greenhouse gas forcing by end of the twenty-first century. The variability associated with sea level pressure, surface air temperature and sea surface temperature explains the projected changes in surface wind field under anthropogenic global warming scenario.