Improved cyclonic wind fields over the Bay of Bengal and their application in storm surge and wave computations

Abstract

Tropical cyclone induced storm surge and extreme waves pose a significant threat and danger to coastal inhabitants as well cause significant damage to infrastructure. Nevertheless, significant progress has been achieved over the past several years in tropical cyclone modeling, there are however inherent limitations in the quality of real-time wind forecast for near-field and far-field regions surrounding the cyclone eye. The reliability and quality of computed storm surge and extreme wind-waves remains a challenge due to their primary association with the quality of input wind forcing. Parametric wind field models are widely used owing to their simplicity and also in realistically representing the inner core region of cyclones. On the other hand, global atmospheric models have inherent limitations in underestimating the inner core winds, although they produce outer core winds much better as compared to the parametric formulation. In this study a blending technique is proposed which takes advantage of both these wind fields thereby producing a blended wind field using a smoothing algorithm and superposition technique that provides realistic estimates of both inner and outer core winds. Numerical simulations with a coupled wave-hydrodynamic model using both blended and the parametric winds were also verified against in situ data. The study reveals that simulations using blended winds performed better and has practical relevance to real-time operational forecasts.