Wave simulations under the effects of geographical complexity over the Strait of Hormuz

Reliable wave estimation in complex body of waters from geographical point of view is a matter of high importance. Main straits in the world, such as the Strait of Hormuz are major referent for this issue. Marine activities such as coastal management and ship routing, navigation, maintenance, and installation of offshore infrastructure are all greatly dependent on reliable wave estimations. Predicting waves in a region requires a well-developed wave model that can account for the shallow water wave mechanisms like their generation, propagation, and dissipation. On the other hand, reliable input wind data is a pre-requisite for realistic wave estimation, while the winds over such environments are highly affected by the land features around the straits. The wind data accuracy is also dependent on horizontal resolution of the models to capture the meso-scale dominant phenomena in the interest region. This study aims to develop a wave model employing SWAN wave model, in order to improve wave estimations over the Strait of Hormuz, where is highly affected by geographical complexity. Initially, the simulation is carried out for more than one month from January to May for period of 40 days of 2011. The main parameters of the model were assigned based on a comprehensive sensitivity analysis study and the model performance was verified based on the available archive field data for two stations Jask and Larak in the eastern part and western part of Strait of Hormuz, respectively. The numerical modeling activities are conducted to adopt two sources of surface wind data. The first adopted dataset, ECMWF’s hourly ERA5 product, is based on the presence of meso-scale locally convective phenomena such as land-seas breeze which is dominant in a water body like the Persian Gulf. ERA5 reanalysis dataset, which is the best available wind source, misses these features (because of low resolution) and in turn, when it is used to force the wave models, may result in predicting less accurate wave fields. For improving wind data accuracy, the second dataset, i.e., the high resolution meso-scale atmospheric model WRF was adopted to generate a more realistic wind field. This model reflects the meso-scale phenomena and using it to force the wave model, reflects more accurate wave fields over study area. Different model resolutions are also tested and the result showed that reducing the horizontal resolution for wind field improves the result. The final model results show a significant improvement in wave estimations in the middle of the Strait of Hormuz for coupling wave model SWAN and using WRF wind data. For Larak station, the RMSE decreases 10 percent in comparison to ERA5 wave data and CC (Corolation Coefficient) get to about 0.75. For Jask staion in eastern part of Strait of Hurmoz, ERA5 wave data CC is about 0.9 which is the best performance.