深圳近海风暴潮影响因素分析

Analysis on the influencing factors of storm surges near Shenzhen

风暴潮可能给沿海城市造成巨大破坏,而深圳位于易受台风影响的南海北部沿岸,经济和人口总量巨大,但有关深圳近海风暴潮的研究工作却十分匮乏。本文基于区域海洋模式系统(regional ocean model system,ROMS)建立了一个以深圳近海为中心的三层嵌套模型,用于研究深圳近海台风所致风暴潮的影响因素。首先对2018年台风“山竹”过境深圳导致的风暴潮进行模拟,模拟结果与观测结果较为一致。在此基础上,进行一系列参数调整试验,研究台风登陆地点、登陆角度、台风尺度、台风强度以及移动速度的改变对风暴潮及其分布的影响。结果表明,在深圳西边登陆的台风,比在深圳东边登陆的台风产生的最大增水高1.5m左右。由东往西移动并登陆深圳的台风,比由南向北移动的台风产生的最大增水高1.0m左右。台风最大风速半径增加15%,最大增水上升0.2m左右。台风强度增强15%,最大增水上升0.4m左右。台风移动速度总体上对风暴潮影响不大,但不同登陆地点存在明显差异。当台风在深圳西边或者东边登陆时,台风移动速度增加30%,深圳沿海各海湾的最大增水反而上升0.2~0.6m。当台风从深圳中部登陆时,台风移动速度增加30%,珠江口的最大增水降低0.1m左右,大鹏湾和大亚湾的最大增水却相反地上升0.2m左右,不同海湾对台风移动速度呈现不同的变化特征,与各海湾水体重新分布到稳定状态时间和台风作用时间有关。

Storm surge can cause huge damages to a coastal city. Shenzhen, as a mega-city in terms of economics and population, is located in the north coast of the South China Sea, where typhoons frequently happen. However, the research on storm surge near Shenzhen is limited. Based on the regional ocean model system(ROMS), a three-layer nested regional ocean model was developed to study influencing factors of storm surges in the coastal region of Shenzhen. First, the storm surge caused by Typhoon Mangkhut in 2018 was simulated and tested, and the simulation results are consistent with observations. Based on the case of Mangkhut, a series of experiments were carried out to study influences of landing location, size, intensity, and moving direction and speed on storm surge. Our results show that, under the same conditions, the maximum storm surge of a typhoon landing on the west of Shenzhen is about 1.5 m higher than that landing on the east of Shenzhen. The storm surge driven by the typhoon passing Shenzhen from east to west is about 1.0 m higher than that moving from south to north. If the radius of maximum wind of a typhoon is enlarged by 15%,the maximum storm surge increases by about 0.2 m. As the intensity of a typhoon goes up by 15%, the maximum storm surge increases by about 0.4 m. On the whole, the translation speed of a typhoon has only weak influence on storm surge, and its influence on storm surges is related to the landing location. If a typhoon makes landfall to the west or east of Shenzhen, and the moving speed of the typhoon increases by 30%, the maximum storm surge in each bay along the Shenzhen coast increases by 0.2 to 0.6 m. If a typhoon passes through each bay of Shenzhen successively, and the moving speed of a typhoon increases by 30%, the maximum storm surge in the Pearl River Estuary decreases by about 0.1 m, and that in Dapeng Bay and Daya Bay increases by about 0.2 m. This is related to the time for the water mass redistribution to return to its a steady state within a bay and the forcing time of the typhoon.