台风影响下广州近岸及珠江口水文气象特征响应

Responds of hydrological and meteorological characteristics in Guangzhou nearshore and the Pearl River Estuary to the influence of typhoon

基于海洋自动观测站实测连续的水文气象数据,对1713号台风“天鸽”和1822号台风“山竹”影响期间广州近岸及珠江口水文气象特征进行了分析,并对海洋灾害影响动力因素进行了探讨。研究结果表明:(1)在台风影响期间,各观测站风速由平时的1~4级增至7~8级,风速均在受台风七级风圈影响6~7 h左右达到最大;潮位均超红色警戒潮位,最大增水2~3 m;波高由平时的1~2级增至3~4级;余流受风速影响先降后增,台风登陆当日余流值最低,台风使余流发生转向;海表温度下降1~2℃,海表盐度增大4~12。(2)对台风的响应由快至慢为:风速、余流、波浪、潮位、水温和盐度,波浪比风速晚1 h达到峰值,最高潮位出现在台风登陆1~2 h后,水温和盐度比风速对台风的响应晚5~6 h。(3)对波浪影响较大的因素主要为台风风圈半径、强台风持续时间、台风级别、移动速度等;对风暴增水影响较大的因素为台风强度和风圈半径,天文大潮、上游流量、地形等对潮位抬升也有一定影响,此外,波浪陡增对风暴增水具有较大影响,相关系数达0.7。(4)“山竹”登陆地点较“天鸽”远74 km且非天文大潮期,但引起的灾害较“天鸽”更严重,引起的最大增水较“天鸽”高30~50 cm,风暴潮等级Ⅱ级以上增水历时较“天鸽”长2.5 h,受4级海况影响时间较“天鸽”长11 h,主要原因是“山竹”的风圈半径远远大于“天鸽”,向陆移动过程中强台风持续时间远远长于“天鸽”。

Based on the long-term continuous hydro-meteorological data from buoys and tidal gauge stations in the upper Pearl River Estuary near Guangzhou,the hydro-meteorological characteristics of this region during the Typhoons Hato and Mangkhut are analyzed,and the dynamic factors causing the marine disasters are also discussed.Results show that firstly influenced by typhoon the wind speed of each station increased from Level 1-4 to 7-8,and the wind speed reached the maximum around 6-7 hours influenced by Typhoon Level 7 wind circle.The tide levels of all station are above the red warning tide level.The maximum storm surge is approximately 2-3 meters.The wave height increased from Level 1-2 to 3-4.The residual current decreased before it increased.The lowest value of the residual current appeared on the day of the typhoon landfall and the typhoon changes the direction of the residual current.The sea surface temperature dropped by 1-2℃and the sea surface salinity increased by 4-12.Secondly,the first response to the typhoon were wind and residual current.The maximum wave height appeared about 1 hour later than the maximum wind speed.The highest tide level appeared in about 1-2 hours later than the typhoon landfall.The changes in sea surface temperature and salinity came later than the wind in about 5-6 hours.Thirdly,the typhoon wind circle radius,the duration of the severe typhoon,typhoon intensity and the moving speed had a great influence on storm surge and wave disaster.The wave height increased sharply and it also had a great influence on the storm surge with correlation coefficient of about 0.7.Fourthly,the landing position of Mangkhut was 74 km farther than Hato,and it was not in the astronomical spring tide period,but the level 7 wind circle radius was 130 km larger than that of Hato.The duration of the severe typhoon was 27 hours longer than that of Hato,so the marine disaster caused by Mangkhut was stronger than Hato.Also,the maximum storm surge was 30-50 cm higher than that of Hato.The Level II storm surge lasted 2.5 hours longer than Hato,and the moderate wave lasted 11 hours longer than that of Hato.