The applicability study of different typhoon wind fields in typhoon wave simulation in Zhejiang sea area
Combined with the Holland wind fields and the ERA5 wind fields,the mixed wind fields was set up by introducing a weight coefficient varying with the radius of wind speed,and a typhoon wave model in Zhejiang sea area was established using MIKE21 SW.Then,the Holland,the ERA5 and the mixed wind fields were used as the input wind fields to simulate the wind speed and the significant wave height during No.1918 typhoon Mitag,respectively.The verification shows that the simulated results obtained using the Holland wind fields and the ERA5 wind fields cannot agree accurately with the observed data,while the mixed wind fields proposed in this study can improve the simulation accuracy.In order to study whether the above conclusion is universal in Zhejiang sea area,five typical typhoons that have the most serious impact on Zhejiang sea area in the recent 5 years were selected for typhoon wave numerical simulations and the error statistical analysis.The results indicate the wind speed around the typhoon center is relatively good using the Holland wind fields and the average relative errors of the maximum wind speed are 8.62%-10.19%,but the average relative errors of the wind speed below 10 m/s is relatively bigger,reaching 29.76%-44.29%.However,the wind speed around the typhoon center using the ERA5 wind fields is smaller than the observed data,and the average relative errors of the maximum wind speed are 17.64%-25.77%,but the average relative errors of wind speed below 10 m/s are smaller than that using the Holland wind fields,which are 19.64%-32.00%.During the five typhoon processes,the average values of the average relative errors of the significant wave height driven by Holland,the ERA5 and the mixed wind fields are 29.92%,25.62%and 22.82%,respectively.Correspondingly,the average root mean square errors are 0.46 m,0.42 m and 0.39 m and the consistency indexes are 0.94,0.95 and 0.96.The above results shows that the mixed wind fields proposed in this study is universal in Zhejiang sea area and can improve the simulation accuracy of typhoon waves.
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