Contribution of tropical cyclone induced waves to the mean and extreme wave climatology in the Bay of Bengal

Abstract

This paper examines the contribution of tropical cyclones (TCs) to the mean wave and the extreme wave climatology in the Bay of Bengal (BoB). To assess the impact of TCs on the wave activity in the BoB, we compare 40-years long WAVEWATCH III (WW3) numerical simulation with a twin experiment, where TC signatures are filtered out from the wind forcing dataset. Our experimental strategy of twin simulations, with and without TCs, allow us to separate the TC-induced waves from the background wave activity and therefore allow us to quantify their contribution. The simulation samples more than 200 TCs in the BoB and is extensively validated against the available buoy observations that measure 39 TCs in the BoB. Results show that TCs contribute up to ~80 % and ~40 % to the extreme significant wave height (SWH) climatology defined as the maximum SWH and highest 1 % SWH and up to ~9 % to the mean SWH climatology during the post-monsoon season with slightly lesser contributions during the pre-monsoon season. This contribution is largest in the northern BoB and along the east coast of India during the post-monsoon season and in the eastern BoB and along the Bangladesh and Myanmar coast during the pre-monsoon season.