Evaluation of ECMWF wind data for wave hindcast in Chabahar zone

Abstract

Wind waves are the most important environmental forces acting on the marine structures. Due to the incompleteness of measured wave parameters, wave prediction plays a key role in the design of coastal and offshore structures. Nowadays, numerical wind wave models are widely used for wave hindcast and forecast. Since wind is the most important forcing term in the numerical wind wave model, the selection of appropriate wind source is a vital step in the wave modeling. In the present study; two wind sources i.e. the measured synoptic and the ECMWF (European Center for Medium Range Weather Forecasts) data, were evaluated for wave simulation near the Chabahar zone. To simulate wave parameters the third generation spectral SWAN model was utilized and the results were compared with those of in situ measurements in a depth of about 17 m. The whitecapping dissipation coefficient and bottom friction factor were used for calibration of the model. The sensitivity analysis showed that other physical parameters have no specific effect on the wave characteristics. Calibration of whitecapping dissipation rate led to the overestimation of high waves. Therefore, a combination of whitecapping dissipation and bottom friction factors was used to calibrate the model. It was found that the SWAN model forced by ECMWF wind data predicted the south-west and west waves successfully while underestimated the east, south-east and south waves. This was mainly due to well prediction of south-west and west wind and underestimation of wind from the east to the south by the ECMWF model. In addition, it was revealed that synoptic wind data can be used as an appropriate wind source for wave hindcasting at the studied area.