0608号台风“桑美”过境前后对长江口外海域环境的影响

台风是短期改变海洋环境的重要动力因素，会对近岸河口环境产生巨大的影响.基于0608号台风“桑美”过境前后长江口外海域多个站位的调查资料，分析了台风过境前后长江口外海域温度、盐度、浊度等环境要素的变化.结果表明:在台风引起的水体平流输运和垂向混合作用下，长江口外海域的温度、盐度、浊度等结构发生了较大改变.表层水体的温度降低，盐度增大；底层水体温度升高，盐度降低；温跃层厚度增大，层结构强度减弱；东部海域的盐跃层基本消失，温盐跃层对营养盐垂向输运的限制减弱，导致叶绿素a浓度值升高；台湾暖流底层冷水明显向近岸涌升，近岸上升流特征更为显著，同时台湾暖流底层冷水的中心位置向东偏移；水体浊度减小，尤其是近岸水深较浅海域，细颗粒沉积物被强平流作用输运. 

The Impact of Super Typhoon Saomai (0608) on the Offshore Environment near the Yangtze Estuary

Typhoon is an important dynamic factor for short-term changes in the marine environment, which have a huge impact on the coastal estuarine environment. Based on the filed observation offshore near Yangtze Estuary before and after the typhoon "Saomai", the variations of water environment factors were analyzed in horizontal and vertical distribution. The results show that the temperature, salinity, chlorophyll a and turbidity changes were largely due to the advection transport and vertical mixing in the water body caused by the typhoon. The surface water temperature decreased and salinity increased, whereas the bottom water temperature increased and salinity decreased. The thickness of thermocline increased and stratifications got weaker than those before the typhoon, and the halocline almost disappeared in eastern area. The vertical transport of nutrient enhanced, causing an increase of the chlorophyll a. After the typhoon, the bottom cold water from the Taiwan warm current rose clearly in coastal area, and the upwelling feature was more significant, and the center of the Taiwan warm current in the bottom shifted eastward. The water turbidity decreased, especially in the shallow coastal waters, fine-grained sediments were flow transported by stronger advection.