基于精细温度观测的南海东北部陆坡-深海盆底层湍流混合  

Bottom turbulent mixing of continental slope-deep sea basin in northeastern South China Sea based on high-resolution temperature observation

作　　者：李杨 黄鹏起 鲁远征[1,2] 屈玲 郭双喜 岑显荣 周生启[1,2,4,5] 张佳政 丘学林[2,3,5] LI Yang;HUANG Pengqi;LU Yuanzheng;QU Ling;GUO Shuangxi;CEN Xianrong;ZHOU Shengqi;ZHANG Jiazheng;QIU Xuelin(State Key Laboratory of Tropical Oceanography(South China Sea Institute of Oceanology,Chinese Academy of Sciences),Guangzhou 510301,China;Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou),Guangzhou 511458,China;Key Laboratory of Ocean and Marginal Sea Geology of Chinese Academy of Sciences(South China Sea Institute of Oceanology,Chinese Academy of Sciences),Guangzhou 510301,China;Institute of South China Sea Ecology and Environmental Engineering(Chinese Academy of Sciences),Guangzhou 510301,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]热带海洋环境国家重点实验室(中国科学院南海海洋研究所),广东广州510301 [2]南方海洋科学与工程广东省实验室(广州),广东广州511458 [3]中国科学院边缘海与大洋地质重点实验室(中国科学院南海海洋研究所),广东广州510301 [4]中国科学院南海生态环境工程创新研究院,广东广州510301 [5]中国科学院大学,北京100049

出　　处：《热带海洋学报》2022年第1期62-74,共13页Journal of Tropical Oceanography

基　　金：国家自然科学基金项目(91952106、41776033、42006196);广州市科技计划项目(201904010312、201804020056)。

摘　　要：南海是存在强湍流混合的边缘海之一,但前人对南海湍流混合的研究更多关注的是中上层,对底层则鲜有关注。本文基于高分辨率温度传感器于2019年5月在南海东北部22个站位海底上方0.5m处持续观测4.4d的温度数据,分析了2216~3200m深度范围内底层海水温度的时间变化特征,并探讨了地形粗糙度和内潮对底层湍流混合的影响。分析结果表明,南海东北部各站位底层海水的温度变化量级约为10^(–4)~10-^(–3)℃;温度变化趋势与正压潮变化趋势不同,温度能谱显示多数站位在全日和半日频带区间出现谱峰,温度变化更多地受斜压潮影响,全日、半日内潮起主要调制作用。陆坡-深海盆过渡区及深海盆底层的湍动能耗散率量级为10^(–10)~10^(–9)m^(2)·s^(–3),涡扩散系数量级为10^(–4)~10^(–3)m^(2)·s^(–1)。观测数据未能显示底层湍流混合与地形粗糙度存在明显的相关性。底层湍流混合的空间分布与过去观测到的南海北部深海盆内潮的南北不对称性分布一致。The South China Sea(SCS)is one of the marginal seas with strong turbulent mixing.More attention was paid on turbulent mixing in the upper and middle layers than that in the bottom layer in previous studies of the SCS.Based on the temperature data obtained in the northeastern SCS with high-resolution records at 0.5 m above the seafloor at 22 stations for about 4.4 days in May 2019,we analyzed the time variation characteristics of bottom-water temperature with ocean depth varying from 2216 to 3200 m,and discuss the influence of topographic roughness and internal tides on bottom turbulent mixing.The analysis results show that the bottom temperature fluctuation at each station is 10^(–4)~10^(–3)℃,the trend of temperature variation is different from that of barotropic tide elevation,the temperature variation is affected by baroclinic process,mainly modulated by the diurnal and semi-diurnal tides at most stations.The magnitude of the turbulent kinetic energy dissipation rate at the bottom of the continental slope-deep basin transition zone and the deep basin is 10^(–10)~10^(–9)m^(2)·s^(–3),and turbulent diffusivity is 10^(–4)~10^(–3) m^(2)·s^(–1).The results,however,cannot reveal the significant positive correlation between the intensity of bottom turbulence mixing and topographic roughness.The spatial distribution of bottom turbulent dissipation is in accord with the north-south asymmetry of internal tides in the deep basin west of the Luzon Strait.

关 键 词：底层温度 湍流混合 内潮 湍动能耗散率 涡扩散系数 南海东北部 

分 类 号：P731.26[天文地球—海洋科学]