Investigation Of Numerical Forecasting Wave Model In Bohai Sea

Based on SWAN(Simulating Wave Nearshore), a model of wave forecasting of shallow water was established in BoHai Sea .Impacts of source term of wind on wave growth and decay are investigated in BOHAI with SWAN (Simulating Wave Nearshore). To attain the optimal parameter in Bohai Sea, we experimented with two kinds of energy input mechanisms of wind (Jassen and Komen), three mechanisms of whitecapping, mechanism of bottom friction and mechanism of Depth-induced wave breaking respectively. As the results illustrated, input mechanism of wind and mechanism of Whitecapping have more effects on wave growth and decay than the other mechanisms. We find that the mechanism of whitecapping depends on the wave number in case of Komen, while the default parameter of SWAN omits this effect (by setting =0.0). The new mechanism of whitecapping introduced by Alkyon et al cause more dissipation of wave energy, because it includes an unseemly parameter.There is generally poor agreement between model results and measurements, when we use default parameters of the formulas used by SWAN to implement the model in Bohai Sea. We find that the proportionality coefficient in linear growth term of wind growth model plays an important role in the process of wave developing. Therefore, we introduce a new formula into the linear growth term of wind growth model. We experiment with two kinds of energy input formula of wind (Jassen and Komen) and three mechanisms of whitecapping to validate the improvement in three wind processes (two cold waves and a south wind). We also adjust the parameters of whitecapping mechanisms based on the Cumulative Steepness Method as described by Alkyon et al. (2002). In conclusion, we find the optimal parameters of formulas used by SWAN for Bohai Sea and agreements with observations are improved via the adjustments. This improvement makes a solid foundation for setting up a proper model of wave forecasting of shallow water in Bohai Sea.