Evaluation and bias correction of global climate models in the CMIP5 over the Indian Ocean region

Global climate model (GCM) simulations driven by various emission scenarios are widely used for the projections of future climate change. In this study, an assessment was carried out by using 35 GCMs under Coupled Model Intercomparison Project (CMIP5) in reproducing the present day wind speed changes over six selected regions in the Indian Ocean region based on altimetry-measured merged wind speed product in the Indian Ocean. The relative ranking of the GCMs is performed based on the evaluation of the CMIP5 historical simulations for the period 1993-2005. The skill level of GCMs in representing the various metrics such as annual mean, mean seasonal cycle, linear trend, correlation coefficient, and seasonal standard deviations was accounted for the relative ranking of the GCMs. The models CMCC-CESM, HadGEM2-ES, and GFDL-ESM2G are found to be better for the Arabian Sea region. The GCM products such as HadCM3, CSIRO-Mk3.6.0, HadGEM2-CC, HadGEM2-AO, and MIROC5 were noticed better for the Bay of Bengal (BoB) region. Large bias in wind speed (similar to 3 m/s) is observed for the head BoB and the Southern Ocean region. Bias corrections for the present-day Representative Concentration Pathway (RCP) simulations (2006-2016) were performed based on quantile mapping (QM) method, and the present-day wind changes are also compared with observations. The findings from study recommend that suitable bias correction for different GCMs is an essential pre-requisite for climate change studies.