Estimates of Reynolds Stress and TKE Production in the Seasonally Stratified East China Sea  

作　　者：YANG Wei ZHAO Liang XU Peng FENG Jianlong WANG Tao QUAN Qi JIANG Wensheng 

机构地区：[1]Key Laboratory of Physical Oceanography, Ministry of Education of China [2]College of Physical and Environmental Oceanography, Ocean University of China [3]College of Marine Science & Engineering, Tianjin University of Science and Technology

出　　处：《Journal of Ocean University of China》2013年第4期549-556,共8页中国海洋大学学报（英文版）

基　　金：supported by the National Basic Research Program of China (973 Program,2010CB428904);the National Science Foundation of China (No.41276016);the Program for New Century Excellent Talents in University (NCET-11-0475);the National Key Technology R&D Program of China (2011BAC03B02)

摘　　要：During the two cruises in March and July of 2011, the tidal cycling of turbulent properties and the T/S profiles at the same location in seasonally stratified East China Sea （ECS） were measured synchronously by a bottom-mounted fast sampling ADCP （acoustic Doppler current profiler） and a RBR CTD （RBR-620） profiler. While focusing on the tide-induced and stratification＇s impact on mixing, the Reynolds stress and the turbulent kinetic energy （TKE） production rate were calculated using the ‘variance method＇. In spring, the features of mixing mainly induced by tides were clear when the water column was well-mixed. Velocity shear and turbulent parameters intensified towards the seabed due to the bottom friction. The components of the velocity shear and the Reynolds stress displayed a dominant semi-diurnal variation related to velocity changes caused by the flood and ebb of M2 tide. Stratification occurred in summer, and the water column showed a strongly stratified pycnocline with a characteristic squared buoy- ancy frequency of N2~ （1-6）x 10 3 S-2 The components of the velocity shear and the Reynolds stress penetrated upwards very fast from the bottom boundary layer to the whole water column in spring, while in summer they only penetrated to the bottom of the pycnocline with a relatively slow propagation speed. In summer, the TKE production within the pycnocline was comparable with and sometimes larger than that in the well-mixed bottom layer under the pycnocline. Considering the associated high velocity shear, it is speculated that the mixing in the pycnocline is a result of the local velocity shear.During the two cruises in March and July of 2011,the tidal cycling of turbulent properties and the T/S profiles at the same location in seasonally stratified East China Sea (ECS) were measured synchronously by a bottom-mounted fast sampling ADCP (acoustic Doppler current profiler) and a RBR CTD (RBR-620) profiler.While focusing on the tide-induced and stratification’s impact on mixing,the Reynolds stress and the turbulent kinetic energy (TKE) production rate were calculated using the‘variance method’.In spring,the features of mixing mainly induced by tides were clear when the water column was well-mixed.Velocity shear and turbulent parameters intensified towards the seabed due to the bottom friction.The components of the velocity shear and the Reynolds stress displayed a dominant semi-diurnal variation related to velocity changes caused by the flood and ebb of M2tide.Stratification occurred in summer,and the water column showed a strongly stratified pycnocline with a characteristic squared buoyancy frequency of N2~ (1 6) ×10 3s 2.The components of the velocity shear and the Reynolds stress penetrated upwards very fast from the bottom boundary layer to the whole water column in spring,while in summer they only penetrated to the bottom of the pycnocline with a relatively slow propagation speed.In summer,the TKE production within the pycnocline was comparable with and sometimes larger than that in the well-mixed bottom layer under the pycnocline.Considering the associated high velocity shear,it is speculated that the mixing in the pycnocline is a result of the local velocity shear.

关 键 词：TKE production Reynolds stress turbulence STRATIFICATION the East China Sea 

分 类 号：P731.2[天文地球—海洋科学]