Numerical Simulation Of Storm Waves Based On The Wind Field From WRF Atmospheric Model

Accurate nearshore wave data in extreme weather is a prerequisite for design safety of port and coastal engineering. It is of great significance to investigate the wave generation and propagation during strong wind processes of typhoon, extratropical storm and cold wave. In recent years, the numerical simulation of waves has become a very important method for sea wave research. However, the reasonability of wave results directly depends on the reasonability of wind data. In addition, the effects of current should be taken into accout in nearshore wave simulation. Therefore, an atmosphere-ocean-wave system was developed to simulate the typhoon and extratropical storm wave process based on the mesoscale atmospheric model of WRF, the two-dimensional tidal current model of FVCOM and the wave model of SWAN. The main contents and results are as follows.(1) Various parameters of WRF under strong wind actions of typhoon and extratropical storm were determined by comparative analysis. The effects of data assimilation under two wind conditions were analyzed. It was indicated that data assimilation had great influence on typhoon wind results while having little influence on extratropical storm wind results. More observation data should be considered to improve data assimilation effects.(2) Comparisons among winds from WRF, QSCAT/NCEP Blended Ocean Winds, and mixed winds of QSCAT/NCEP and typhoon model showed that the WRF simulation data agree with the observation data more satisfactorily than the other data. WRF model can well simulate the wind speeds and directions in typhoon and extratropical storm and can provide high-precision wind data for wave simulation.(3) The two-dimensional tidal current model of FVCOM and SWAN wave model were applied to simulate the current and wave processes for the WIPHA typhoon in 2007 and the extratropical storm occurred in March, 2007. It is shown that the numerical models could well simulate the current and wave process of WIPHA typhoon and the extratropical storm.(4) The analysis of wave propagation under typhoon wind conditions indicated that the wave direction varied and was gradually consistent with wind direction with a circular wave field, but the center of wave field had a time delay compared to typhoon wind center.(5) The effects of tidal current on wave in shallow water were analyzed. It is verified that the tidal current had a remarkable effect on wave height in shallow water of nearshore zone. It is suggested that the effects of tidal current should not be neglected in nearshore wave simulation.