Observations of turbulent mixing and vertical diff usive salt fl ux in the Changjiang Diluted Water  

作　　者：Baisu ZHU Wei YANG Chengfei JIANG Tao WANG Hao WEI 

机构地区：[1]School of Marine Science and Technology,Tianjin University,Tianjin 300072,China [2]Key Laboratory of Marine Environment and Ecology,Ocean University of China,Qingdao 266100,China

出　　处：《Journal of Oceanology and Limnology》2022年第4期1349-1360,共12页海洋湖沼学报（英文）

基　　金：Supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA23050502);the National Natural Science Foundation of China(No.41906006)。

摘　　要：Based on microstructure measurements from a repeated sampling station southwest of the Jeju Island during summer,we studied the hydrography,pycnocline turbulence,and vertical salt fl ux in the Changjiang Diluted Water(CDW).The water column was well stratifi ed with the CDW occupied the surface~20 m.Most of the large turbulent kinetic energy dissipation rate(ε)were found in the bottom boundary layer.Interestingly,intermittent strong turbulence(ε>10^(-6) W/kg)occurred in the pycnocline,which may induce strong mixing events and increase the vertical diff usive salt fl ux at the base of CDW by one order of magnitude.The daily-mean vertical diff usive salt fl ux could reach 4.3(2.1,8.9)×10^(-6) m/s.Both moored velocity measurements and associated wavelet analysis showed the presence of velocity fl uctuations when there was strong pycnocline turbulence.The moderate resolution imaging spectroradiometer(MODIS)satellite images further suggest that the velocity fl uctuations are induced by the prevailing internal solitary waves(ISWs)which are mainly generated at the shelf break of the East China Sea or the topographic features surrounding Jeju Island.The calculated gradient Richardson number denote the occurrence of shear instability in the pycnocline when strong turbulence presents.The presented results have strong implications for the importance of ISWs in infl uencing the vertical diff usion of CDW and changes in other properties.

关 键 词：TURBULENCE vertical salt flux internal solitary wave Changjiang River plume 

分 类 号：P333[天文地球—水文科学] P731[水利工程—水文学及水资源]