Application In The Accuracy Verification Of Autonomous Ocean Satellite Data And The Numerical Simulation Of Typhoon Waves

The ocean accounts for 71% of the Earth’s surface area,contains abundant energy and resources,and plays an important role in regulating the Earth’s climate and environment.Throughout history,humans have been striving to explore and understand the ocean,especially since the 20 th century,when a wave of ocean research began.As a maritime power,China has nearly 10000 square kilometers of ocean,and its coastline is10000 kilometers long,making it the fourth longest in the world.The long coastline also means that the area affected by marine disasters is extensive,especially during the Pacific typhoon season from May to August each year,which includes China,Japan,South Korea,and other affected areas.Typhoons can play an important role in promoting global climate regulation on one hand,while also causing significant economic losses to neighboring countries,especially economically developed coastal cities.In recent years,with the development and improvement of remote sensing satellites and wave numerical simulation technology,research on the ocean is entering a new height.This article mainly studies autonomous ocean satellites and the widely used third-generation wave numerical model WAVEWATCH-III from two aspects,exploring the accuracy verification of autonomous satellites and the applicability of wave numerical simulation in extreme ocean dynamic processes.The first part introduces the data accuracy exploration of China’s autonomous ocean satellite HY-2B.In the second part,based on the wind speed and wave spectrum information measured by the China France Ocean Satellite(CFOSAT),the drag coefficients of the WW3 wave model were re fitted during the typhoon process,and a more adaptable parameterization scheme for the drag coefficients was found,which improved the applicability of the model during the typhoon process.In the first part of the paper,the accuracy of HY-2B altimeter and scatterometer data is mainly studied in the accuracy verification of HY-2B satellite data.By obtaining HY-2B data of 20 typhoon processes in China’s offshore waters from 2019 to 2020,the accuracy of HY-2B data under normal and extreme sea conditions is discussed and evaluated.In order to compare data accuracy,HY-2B scatterometer and ASCAT wind field,HY-2B altimeter and Jason 3 altimeter data,and WW3 wave model simulated wave data are matched.The comparison results between HY-2B scatterometer and ASCAT wind field show that the root mean square error(RMSE)of wind speed is 0.78m/s,and the correlation(COR)between the data reaches 0.97.Since the HY-2B altimeter also has sea surface wind data,the ASCAT wind field is matched with the sea surface wind field data observed by the HY-2B altimeter.The results show that the root mean square error(RMSE)of wind speed is 1.2m/s,and the correlation(COR)is 0.93.The sea surface wind field observed by the HY-2B scatterometer data is more accurate.In the second part,the typhoon process drag coefficient of the WW3 wave model was optimized using the sea surface wind field and wave spectrum data from China France Star.A new set of parameterization schemes for typhoon process drag coefficients was obtained by collecting 20 typhoon process observation data from 2019 to 2020,using sea surface roughness related formulas and data fitting.The effective wave height parameters(Hs)simulated using the WW3 model were compared with the observed effective wave height results of several anchored buoys during three typhoon activities(Typhoon Phoenix in 2014,Typhoon Canhong in 2015,and Typhoon Lichma in 2019),verifying the accuracy of the new towing scheme.The comparison results show that the new drag coefficient parameterization method obtained by fitting significantly improves the accuracy of WW3 model in simulating typhoon waves.From the comparison results,it can be seen that the root mean square error of the effective wave height and the scattering coefficient(SI)of the new fitting formula in the application of the sea wave model are 0.49 m and 0.35,respectively.The effect of the new fitting formula is better when applied to the model simulation process.From this result,it can be seen that the parameterized drag coefficient equation newly fitted with Chinese and French satellite data is more effective in simulating ocean waves in WW3,especially for sea conditions with effective wave heights less than 7m.In addition,using the proposed parameterization scheme,the accuracy of simulating ocean waves did not decrease with increasing wind speed and sea conditions.However,the applicability of the proposed new parameterization requires new research and discussion when wind speeds exceed 30m/s.