What is a storm surge?

Storm surge is a kind of marine disaster along the coast. This kind of disaster is mainly caused by strong wind and high water level. The reason for this is that there is strong wind along the coast. The strong winds formed in the ocean are mainly typhoons and extratropical cyclones. Typhoons occur in tropical oceans and are very destructive. Internationally, it is called a tropical cyclone, and the Atlantic Ocean and the Northeast Pacific Ocean are called hurricanes. There are about 80 typhoons in the world every year, of which 1/3 can cause typhoon storm surge. The extratropical cyclone is also called extratropical depression, or peak cyclone. The gale formed by this cyclone is not as strong as that of a typhoon, but its influence range is larger than that of a typhoon, with an average of 1000 km and a maximum of more than 3,000 km. Therefore, the storm surge caused by extratropical cyclones is also very common.

Whether storm surge can become a disaster sometimes depends on whether it meets the astronomical tide at that time. If the two tidal levels are superimposed together, there is a great possibility of disaster. The severity of storm surge disaster is not only restricted by the size of storm surge and local astronomical climax, but also depends on the geographical location, coastal shape, seabed topography and socio-economic conditions of the affected areas. Generally speaking, storm surge disasters are relatively serious in areas with strong winds at sea, trumpet-shaped coast, flat seabed, high population density and developed economy.

According to statistics, near tropical cyclones and temperate cyclones, it is extremely vulnerable to strong winds and produces storm surges. Specifically, there are eight tropical cyclone prone areas in the world, among which the northwest and northeast Pacific, the north Pacific, the Bay of Bengal, the south Pacific and the southwest Indian Ocean are more prominent. Temperate cyclone prone areas are mostly distributed in the sea area north of 20 north latitude, and generally do not appear in the south of 20 north latitude.