| Storm surge is an abnormal rise in sea level caused by intense atmospheric disturbances that occurs outside of the predicted astronomical tides.Typhoon-caused storm surges are most common in the summer and fall in China,and they primarily affect the country’s southeast coast.Storm surges induced by tropical cyclones are more severe than extratropical storm surges,resulting in higher mortality and economic damage.The purpose of this article is to examine the characteristics of typhoon storm surge fluctuation and the impact of climate change on storm surges along the Chinese coast.We use harmonic analysis to calculate astronomical tide levels and storm surges based on observed water level data from 9 sites along China’s southeast coast since 1958.The amplitude and phase lag of astronomical tides in coastal China are observed to vary significantly from year to year,with an 18-year fluctuation period.Storm surges during the summer half of the year are often stronger than those during the winter half of the year,according to the findings.From July through October,there were no storm surges with water levels above 1 meter.Taiwan’s stations have a smaller storm water increase than other mainland coastal stations,and the eastern stations are stronger than the southern stations.These nine stations are divided into three areas: the southern stations(Beihai,Zhapo,Hongkong,Shanwei),the eastern stations(Xiamen,Sansha,Kanmen),and the Taiwanese stations(Kaohsiung,Keelung).By examining long-term variations in storm surge amount,length,and intensity,it was discovered that,with the exception of Kanmen station,typhoon storm surge has been decreasing in recent decades.From 1975 to 1995,there were few extreme water increase events in the eastern stations,although typhoon storm surge in the eastern stations exhibited a clear upward trend after 1980.It is found that there are obvious spatial differences of the effects of El Ni(?)o-Southern Oscillation(ENSO)on storm surges.The intensity of storm surge is stronger in eastern stations during El Ni(?)o years,and lower in southern stations during El Ni(?)o years.They are opposite during La Ni(?)a years.The storm surge intensity of most stations during the cold phase of Pacific Decadal Oscillation(PDO)is stronger than that during the warm phase.ENSO and PDO affect the storm surge by influencing the intensity,number and path of typhoons that affect the Chinese coast.During El Ni(?)o years,tropical cyclones have a further genesis area,longer track,higher intensity,and a more northerly landing position,while during La Ni(?)a years,tropical cyclones have a closer location,shorter track,and weaker intensity.In the cold phase of PDO,tropical cyclones landed at higher latitudes. |
