Evaluation of wave growth and bottom friction parameterization schemes in the SWAN based on wave modelling for the central west coast of India

Abstract

In the present study, SWAN wave model is nested with Wavewatch 3 to reproduce waves off the central west coast of India using ERA-5 winds. The sensitivity of SWAN wave model was tested with different wave growth and bottom friction schemes to identify the most suitable scheme for this region. The model parameters have been validated with one year buoy measurements. Among all the four wave growth schemes (Komen, Janssen, Westhuysen and ST6) and three friction schemes (JONSWAP, Collin and Madsen) considered, SWAN with Komen or ST6 and JONSWAP setup performed better in predicting the waves, including the high waves during the southwest monsoon. Model performance has also been tested with high resolution WRF winds and the statistical results showed comparably the same performance as ERA5 winds. The model very well demonstrated the existence of single peaked spectra during the southwest monsoon and double/multi-peaked spectra due to strong local winds and the swells arriving from the Southern Ocean during fair/moderate weather season. Hence, Komen or ST6 wave growth with JONSWAP bottom friction is recommended for the prediction of waves off the central west coast of India using ERA5 winds.