Potential impact of climate change on extreme waves

Abstract
Wind-wave field plays a major role in the planning and designing of important coastal structures. The study on wave characteristics is considered necessary for the routing of ships, wave hindcasting and forecasting. Climate change is one of the major threat that has been occurring over the years and the impact of climate change on wave climate results in increased storm effects and rough sea conditions. Bay of Bengal (BOB) being the active cyclonic region along the North Indian Ocean experiences severe storms every year during the onset of north-east monsoon. Hence, wind wave modelling of the cyclonic storms in the BOB region is required for the analysis of wave climate. The present study considers three severe cyclonic storms in the BOB region: Phailin which occurred during October 2013; Hud-hud during October 2014; and, Vardah during December 2016. The study further details about the impact caused by these cyclone when projected to the future under the climate change scenarios. Thus the wave climate of the three considered cyclones are projected for the Representative Concentration Pathway (RCP) scenarios of RCP4.5, RCP6.0 and RCP8.5 both for the Near-Future (2035) and Far-Future (2075) categories. The surface wind of the chosen domain for the projected scenarios is obtained from the Weather Research and Forecasting (WRF) model and then these winds are forced into the WAve Model (WAM) to predict the corresponding wave climate. The significant wave height (Hs¬) obtained from the WAM model for the projected scenarios has been compared to the present scenario of the respective cyclones and the results show an increase in intensity for all the three cyclones under the Far-Future categories of RCP6.0 and RCP8.5 scenarios. The Hud-hud cyclone has the greatest intensity of about 21% under the Far-Future category. Further, to improve the accuracy of the WAM model on the event of extreme waves in the BOB region, tuning of parameters in the model source terms is required.
Keywords: Cyclonic wave climate, RCP scenarios, WAM