Skill assessment of global climate model wind speed from CMIP5 and CMIP6 and evaluation of projections for the Bay of Bengal

Abstract

Atmospheric and oceanic parameters derived from global climate model (GCM) simulations have received wide global attention and importance in representing the future world under different scenarios of greenhouse gas emissions. The present study deals with near-surface wind speed in the Bay of Bengal (BoB) obtained from CMIP5 and the upcoming CMIP6 GCMs and validation exercise clearly signify improved performance of CMIP6 GCMs over CMIP5. Multi-model ensemble mean corresponding to the four emission scenarios are constructed using the best performing models of CMIP6 family. The study reveals that near-future changes in wind speed in the BoB are moderate under the low-end scenario of SSP1-2.6. Projected wind speeds in the head BoB are expected to increase or decrease by 20% during June–July–August and December–January–February under high-end scenario by the end of twenty-first century. A positive change up to 30% in the northeast monsoon winds under SSP5-8.5 is projected in the central BoB. Irrespective of the seasons, a net increase amounting to 0.6–0.8 m/s is observed along the east coast of India under SSP2-4.5 scenario by the mid and end of the century. Maximum rise by 25% (0.5–1 m/s) in wind speed is predicted under SSP3-7.0 scenario in the near future. Further, the study points out a decline in wind speed by 0.2–0.8 m/s in the central and southern BoB under the extreme scenario of SSP5-8.5. Strengthening and weakening of winds over the BoB accounts the projected variations in temperature that resulted from global warming and subsequent changes in atmospheric circulation.