Numerical Simulation And Statistical Analysis Of Typhoon Waves Along Jiangsu Province

Typhoon waves refer to the waves generated by disturbances caused by tropical cyclones(tropical depressions,typhoons,and super typhoons)occurring on the tropical ocean surface.Once disasters occur,they will cause varying degrees of damage to coastal engineering in China.Under the influence of global climate change,the marine environment is increasingly deteriorating,and typhoon wave disasters frequently occur along the coast of the mainland.Today,China’s sustainable economic development increasingly relies on the development of marine resources,and the working environment of marine operations is facing increasingly severe challenges.The coastline of Jiangsu Province is 953.9 km long,with open beaches,large tidal flats and shallow seas,poor shelter conditions,and a very fragile marine environment,which is extremely vulnerable to the threat of typhoon waves.Analyzing long-term typhoon data and simulating typhoon waves are of practical significance for offshore work,coastal engineering planning,and marine engineering protection along the Jiangsu coast.Therefore,this article uses numerical simulation and statistical analysis methods to simulate and analyze typhoon waves along the Jiangsu coast for many years,aiming to provide theoretical basis for Jiangsu marine engineering construction and theoretical data for Jiangsu marine disaster prevention and reduction work.In order to provide data support for the analysis of typhoon wave heights along the Jiangsu coast,the terrain depth used in the SWAN model is spliced from the global land and ocean elevation data ETOPO1 and the measured water depth data;the wind field data used in this article comes from the latest generation of atmospheric reanalysis data EAR5 provided by the European Center for Medium-range Weather Forecasts,which is used to drive the SWAN model and establish a numerical model of typhoon waves suitable for the Jiangsu coast.Three typhoons were selected to validate the model,and the calculated data was compared with the measured data,indicating that the numerical simulation results are in good agreement with the measured data.Using the well-validated numerical model,60 typhoons passing through the Jiangsu waters from 1971 to 2021 were calculated,and the simulation results were statistically analyzed.Firstly,through statistical analysis,extreme values of typhoon wave height in the past 51 years were obtained for ten ports along the Jiangsu coast.The results showed that in the past 20 years,there has been a gradual increase in typhoon wave height along the Jiangsu coast,and spatially,the extreme values of typhoon wave height in the Jiangsu coastal area mainly exhibit a characteristic of being high in the north and south,and low in the central part.Then,four typical typhoons in the Jiangsu coastal area were selected for temporal and spatial feature analysis,and it was found that the first and second types of typhoons caused the highest typhoon wave heights near the Jiangsu coast,and spatially,the typhoon wave heights exhibited a characteristic of being high in the north and south,and low in the central part.Moreover,there was a high correlation between wave height and period during the four typical typhoon processes.Finally,four composite extreme value distribution models were established to obtain the return periods of extreme typhoon wave heights in the Jiangsu coastal area,and the goodness-of-fit of each model was compared.The comparison results showed that the Poisson-Weibull composite extreme value distribution had the best fitting effect for the extreme typhoon wave heights in the Jiangsu coastal area.Using the PoissonWeibull distribution,the extreme values of typhoon wave heights with a return period of several decades were calculated,and it was found that the typhoon wave heights produced by a 50-year return period typhoon in the Binhai and Lusi ports along the Jiangsu coast were relatively high,with values of 4.97m and 4.91m,respectively.