Assimilation of significant wave height from EnviSAT in coastal wave model using optimum interpolation at variable wave height ranges

Abstract

In this study significant wave height (SWH) from EnviSAT radar altimeter data has been assimilated in the coastal ocean wave model SWAN (Simulating WAve Near-shore). Optimum interpolation (OI) technique has been used for this purpose. A detailed validation of the model and the EnviSAT observations has been carried out prior to the assimilation for the determination of the error covariance matrix of prediction and observation. Validation of the EnviSAT data and the model is done using the in-situ buoy observations and Jason-1 altimeter data. Validation exercise revels that at various ranges of SWH the error covariance changes significantly for both the model and the altimeter measurements. Result shows that the assimilation of EnviSAT data at various ranges of SWH, using optimum interpolation scheme in SWAN model improves the prediction by 15-20%. Also there is reduction in the RMSE of SWH by 0.2 m. Multi-mission altimetric data assimilation using the same technique can improve the model prediction significantly.