Improvements in wind field hindcast for storm surge predictions in the Bay of Bengal: A case study for the tropical cyclone Varadah

Abstract

Forecasting the storm surges is crucial to prevent the enormous devastation of coastal ecosystems, habitats, and economic losses. Further, estimating ocean wave parameters in tropical areas is difficult due to the complexity of wind fields associated with tropical cyclones (TCs). Usually, parametric and global model wind fields are the two primary sources to acquire wind and pressure fields to estimate the storm surges. The parametric models usually depict a better wind field near the cyclone center. Unlike the parametric models, the wind fields from global models have better accuracy in the areas far away from the eye of the cyclone. Owing to this inconsistency, a blended wind field approach has been introduced. However, there are no consensus on selecting parametric and background wind models due to the lack of a rigorous assessment of different wind models in the Bay of Bengal (BoB) region. Hence, in this study, five well-known parametric wind models, namely, Jelesnianski (SLOSH), rankine vortex (RV), Willoughby (WL06), Holland (HL80), and generalized asymmetric holland model (GAHM); and, two global wind models, namely, european center for medium-rangeweather forecasts (ECMWF), and weather research forecast (WRF) models were investigated with the available predictions and measurements in BoB. After investigating the best wind model in this region, a detailed analysis was carried out for the TC Varadah in the BoB region. Further, this study provides insight into the deviations in the resulting simulated surge, wave characteristics, and inundation induced by the different atmospheric forcing wind models. The results reveal that a blended wind model based on GAHM and WRF can better simulate the background wind field and the internal structure of the cyclone for the BoB region.