夏季长江口及其邻近海域湍流特征分析  

Characteristics of turbulence in the Changjiang River Estuary and its adjacent waters in summer

作　　者：王寇 李博 李爱国 王鹏皓 裴生鑫 Wang Kou;Li Bo;Li Aiguo;Wang Penghao;Pei Shengxin(Marine Science and Technology College,Zhejiang Ocean University,Zhoushan 316022,China;Zhoushan Natural Resources Survey-ing and Mapping Design Center,Zhoushan 316021,China;College of Meteorology and Oceanography,National University of Defense Technology,Nanjing 211100,China)

机构地区：[1]浙江海洋大学海洋科学与技术学院,浙江舟山316022 [2]舟山市自然资源测绘设计中心,浙江舟山316021 [3]国防科技大学气象海洋学院,江苏南京211100

出　　处：《海洋学报》2021年第11期22-31,共10页

基　　金：国家重点研发计划重点专项(2017YFA0604904);国家自然科学基金青年基金(41706022);国家自然科学基金(41849903)。

摘　　要：利用2019年7月在长江口科学考察实验研究夏季航段(NORC2019-03-02)中获得的MSS90L湍流剖面仪的直接观测数据,本文计算并分析了该断面的湍动能耗散率ε和垂向湍扩散系数KZ的分布情况。湍动能耗散率的大小为1.72×10^(−10)~2.95×10^(−5)W/kg;垂向湍扩散系数的大小为3.24×10^(−7)~4.55×10^(−2)m^(2)/s。湍动能耗散率和垂向湍扩散系数的分布相似,均为上层最强,底层次之,中层最弱。上层由于风应力的作用,使得湍动能耗散率和垂向湍扩散系数较大;温跃层处层化较强,抑制了湍动能的耗散和垂向上的湍混合。盐度锋面的次级环流会促使低盐水团脱离,锋面引起的垂向环流会加强海洋的湍混合。低盐水团与外界的能量交换较少,湍动能耗散率较弱。长江口海区存在明显的上升流和下降流,它们是由锋面的次级环流产生的;上升流和下降流的存在促进湍动能的耗散与湍混合。Using the direct observation data of the MSS90L turbulence profiler obtained in the summer cruise of the Changjiang River Estuary scientific investigation and experimental study(NORC2019-03-02)in July 2019,in this paper,the distribution of the turbulent kinetic energy dissipation rateεand the vertical turbulent diffusion coefficient Kz are calculated and analyzed.The turbulent kinetic energy dissipation rate is 1.72×10^(−10)W/kg to 2.95×10^(−5)W/kg,and the vertical turbulent diffusion coefficient is 3.24×10^(−7)m^(2)/s to 4.55×10^(−2)m^(2)/s.The distribution of the turbulent kinetic energy dissipation rate and the vertical turbulent diffusion coefficient are similar,both of which are the strongest in the upper layer,the next in the bottom layer and the weakest in the middle layer.In the upper layer,due to wind stress,the turbulent kinetic energy dissipation rate and vertical turbulent diffusion coefficient are larger;the stratification is stronger at the thermocline,which suppresses the dissipation of turbulent kinetic energy and ver-tical turbulent mixing.The secondary circulation of the salinity front will promote the separation of the low salt wa-ter mass,and the vertical circulation caused by the front will enhance the turbulent mixing of the ocean.The energy exchange between the low salt water mass and the outside world is less,and the turbulent kinetic energy dissipation rate is weaker.There are obvious upwelling and downwelling in the Changjiang River Estuary,which are produced by the secondary circulation of the front;the existence of upwelling and downwelling promotes the dissipation of turbulent kinetic energy and turbulent mixing.

关 键 词：长江口 温跃层 湍动能耗散率 垂向湍扩散系数 盐度锋面 

分 类 号：P731.21[天文地球—海洋科学]