An innovative ocean state forecasting approach using SWAN+ WAVEWATCH III modelling system for Indian coastal waters

摘要: Sustained advancements in the developed ocean wave models are of paramount importance to get realistic simulations of the ocean wind waves. In the present study, a novel technique viz.,‘Boundary Condition Impartation Technique’(BCIT) has been developed and implemented to directly nest an unstructured mesh version of the coastal wave model Simulating WAves Nearshore (SWAN)(configured for the Indian coastal region) with the global wave model WAVEWATCH III (WWIII). An important advantage of this technique is that it eliminates the need for an intermediate structured SWAN, which typically required significant computational resources. Integrated SWAN+ WWIII modelling systems for the east and west coasts were configured separately using BCIT and evaluated for normal as well as cyclonic situations using observational data. The results suggest that this method of nesting of the two models works well, and has a significant effect in filling up the energy in the low-frequency part of the wave energy spectra, as evidenced by the spectral energy density plots. Statistics of model errors before and after the integration shows that errors are reduced significantly after integration of the models using this approach. Accuracy in the prediction of significant wave height was improved by 45% for Kollam (a west coast site), and 35% for Tuticorin (an east coast site) upon inclusion of open boundary conditions, thus highlighting the effectiveness of this newly developed technique. The scatter index for significant wave height and mean wave period were below 0.3 even during extreme conditions, indicating that the model setup could safely be used …