台风"纳沙"期间广西近岸风暴射流产生与增减水异常现象

利用长度为1年的广西近岸观测站的ADCP数据和有关潮位观测结果,针对2011年"纳沙"台风期间引发的广西沿岸西向风暴射流和增减水变化过程对应关系,分析台风期间广西近岸西向风暴射流产生的主要原因。结果发现:台风登陆期间S1站表、底层实测流速均比无台风期间流速增大将近两倍,余流流速最大值超出正常值3倍以上;台风消退时底层流向恢复最快,表层较慢;广西近岸强劲西向风暴射流的产生,可能是入海径流与台风将海水向北输运两种作用叠加导致的;台风引起的水位增减变化具有先减后增的规律。在距离海岸不到1 km处产生如此大的西向风暴射流实属少见,深入开展台风期广西沿岸西向风暴射流在传入近岸港湾后的变形、分布及衰减的理论问题研究,对于近海生态系统及环境保护具有重要的理论和现实意义。

Storm Jet and Water Level Fluctuations Induced by Typhoon Nesat in Guangxi Coastal Area

Based on ADCP data and observations on tide levels observed for 1-year from Guangxi coastal observation station, the corresponding relationship between the westward storm jet and the water fluctuations induced by typhoon Nesat in 2011 was analyzed to indentify the main course of the generation of strong western storm jet during typhoon period. The results found that during the landing of Nesat, the measured velocity of the surface layer and bottom layer at the S1 station increased by nearly two times compared with that during the absence of typhoon, and the maximum value of the residual current velocity exceeded the normal value by more than three times. When the typhoon subsided, the bottom current direction recovered fastest and the surface layer recovered more slowly. Runoff into the sea and typhoons in Guangxi coastal area transported seawater northward, and these two effects overlapped together and led to the generation of a strong westward storm jet. The water fluctuations induced by typhoon Nesat showed a regularity of first decreasing and subsequently increasing. It was rare to produce such a large westward storm jet at the distance less than 1 km from the coast. During typhoon period, the westward storm jet along the Guangxi coast deformed, changed the distribution and declined the intensity after entering the harbor. In-depth research on these theoretical problems was conducted, which had important theoretical and practical significance for coastal ecosystems and environmental protection.