海洋次表层SCVs的特征与成因机制:问题与进展

doi:10.3969/j.issn.1001-909X.2023.02.004

摘要/Abstract

摘要：

随着观测技术的进步和海洋数值模拟能力的提升,已发现在海洋次表层中广泛存在一种远离生成源区、结构紧致且稳定的次表层强化的SCVs,其动力学特征表现为:弱层结,低位涡中心,外围等密度线呈透镜状结构,温度、盐度或其他示踪量的性质与周围水体相比存在明显异常,内部核心流速较强。此类次表层SCVs对于海洋的水体运输、热盐环流和海洋生物生态环境均有重要影响。该文通过综述海洋次表层SCVs的结构及水文特征、识别方法、次表层SCVs在全球的分布、动力学机制及其重要影响等,展现次表层SCVs的研究进展,提出了未来研究的方向,包括研究的难点和全面认识海洋次表层SCVs尚待解决的问题。

关键词: 海洋次表层, 次表层SCVs, 动力学特征与机制

Abstract:

With the advancement of observation technology and the improvement of ocean numerical simulation capabilities, some stable subsurface coherent vortices have been widely observed in the ocean, which far from the formation source area. These vortices possess distinctive dynamic characteristics, such as a low potential vorticity center, lens-like structure of isopycnals, weak stratification, and anomalous temperature, salinity, or other tracer properties compared to the surrounding water mass. Their core flow is relatively stronger. These subsurface coherent vortices significantly impact ocean water mass transport, thermohaline circulation and marine biological environment. This paper comprehensively summarizes researches on subsurface coherent vortices in the ocean, including their structure, hydrological characteristics, identifying methods, global distribution, dynamic mechanisms and their important effects on ocean environment. Furthermore, the research perspectives are discussed, such as the difficulties in the research and the issues that need to be solved to comprehensively understand subsurface coherent vortices in the ocean.

Key words: ocean subsurface, subsurface coherent vortex, dynamic characteristics and mechanism

中图分类号:

P731.2

戈玉宇, 廖光洪. 海洋次表层SCVs的特征与成因机制:问题与进展[J]. 海洋学研究, 2023, 41(2): 45-60.

GE Yuyu, LIAO Guanghong. Characteristics and mechanism of ocean subsurface coherent eddies: Problems and progress[J]. Journal of Marine Sciences, 2023, 41(2): 45-60.

图/表 10

图1 当前几种常用观测手段所识别出的次表层SCVs [a:夏威夷海洋时间序列(HOT)航次在ALOHA观测站(22°45'N, 158°00'W)通过高分辨率采样获得由次表层(300~500 m)涡旋引起的位温(θ)、盐度(S)、溶解氧(O2)、浮力频率(N)和荧光剂(Fl)异常,图中黑色曲线为121航次观测剖面,彩色曲线为122航次观测剖面[14];b:Argo浮标(WMO ID 3900556)于2007年在南太平洋副热带东部区域观测的上层600 m时间-深度-盐度剖面图[15],图中黑色线为盐度等值线,白色线从上往下分别为位势密度(σθ=26.0,26.2,26.5,26.7和27.0 kg·m-3)等值线;c:2004年秋季由水下滑翔机观测到加利福尼亚潜流涡旋(Cuddy)引起的涩度异常剖面图[4],图中叠加了位势密度异常等值线(品红色线)、沿岸地转流流速等值线(黑色线为向极地方向、灰色线为向赤道方向,粗黑线是流速为0 m·s-1的等值线),位势密度和地转流流速等值线间隔分别为0.2 kg·m-3和0.02 m·s-1,高亮且粗的品红色线表示σθ=26.55 kg·m-3 等位势密度线,代表加利福尼亚潜流流核位置;d:北大西洋地震反射数据观测到的次表层地中海涡旋(Meddy)[16]。]

Fig.1 Subsurface coherent vortices identified by some observation methods [a: Potential temperature (θ), salinity (S), dissolved oxygen (O2), buoyancy frequency (N) and fluorescence (F1) profiles from ALOHA station (22°45'N, 158°00'W) during Hawaii Ocean Time-series (HOT) cruises 121 (black lines) and 122 (colored lines) [14]; b: Time-depth sections of salinity during 2007 in the upper 600 m from Argo float WMO ID 3900556, located in the eastern subtropical South Pacific Ocean[15], with the black line for salinity contours. Contours for σθ=26.0,26.2,26.5,26.7 and 27.0 kg·m-3 from top to battom are overlaid in white; c: Profile of anomalously spicy caused by California undercurrent eddy (Cuddy) observed by underwater glider from autumn 2004[4]. The figure superimposes the potential density anomaly (magenta contours), and alongshore geostrophic velocity (black contours poleward, gray contours equatorward, zero contour heavy line), The contour interval for potential density (velocity) is 0.2 kg·m-3 (0.02 m·s-1). The California undercurrent core isopycnal ofσθ=26.55 kg·m-3 is highlighted by the thick magenta line; d: Mediterranean eddy (Meddy) observed from the North Atlantic seismic reflection data[16].]

图2 再分析数据探测到的黑潮延伸体区域次表层SCVs结构 (图中的白色线代表混合层深度。)

Fig.2 Structure of subsurface vortex detected using reanalysis data in Kuroshio extend region (White lines indicate mixed layer depth.)

图3 应用再分析数据探测到的黑潮延伸体区次表层SCVs的三维结构

Fig.3 3D structure figure of subsurface vortex detected by reanalysis data in Kuroshio extend region

表1 在全球观测发现的典型次表层SCVs

Tab.1 Typical subsurface coherent vortices found in the global ocean

区域	温跃层内涡旋(ITEs)		温跃层下涡旋(STEs)				模态水涡旋
区域	主要结论	代表性文献	涡旋名称	主要结论	代表性文献		主要结论	代表性文献
印度洋	表层反气旋涡与热带气旋相互作用可能产生ITEs	GORDON et al^[23]	阿拉伯涡旋	阿拉伯海观测到的STEs在咸水横跨阿拉伯海的运输中具有重要作用	VIC C et al^[25], MAREZ et al^[26]
印度洋	在马达加斯加东南部观测到ITEs	NAUW et al^[24]	阿拉伯涡旋	阿拉伯海观测到的STEs在咸水横跨阿拉伯海的运输中具有重要作用	VIC C et al^[25], MAREZ et al^[26]
大西洋	综合大西洋西部永久性温跃层中等温透镜体的观测结果,解释其为孤立特征,首次提出ITEs,同时在马尾藻海中观测到ITEs	DUGAN et al^[20]	地中海涡旋	地中海涡旋将高盐的地中海水输送到亚热带大西洋,影响环流、深对流、生物化学物质等	MCDOWELL et al^[29], RICHARDSON et al^[30], BARBOSA et al^[31], BOSSE et al^[3,32-33]	模态水涡旋在大西洋西北部被观测到,它们通过沿密度面输送和动量搅拌热盐、化学物质等影响海洋环流从而影响生态		MCGILLICUDDY et al^[34]
	在副热带北大西洋东边界上升流潜流中观测到ITEs,其内部和周围生产力很高	PIETRI et al^[12]				北大西洋东部的海洋低氧区的形成与模态水涡旋的孤立水团输运有关		SCHüTTE et al^[35]
	在墨西哥湾观测到的ITEs对墨西哥湾热量、盐度再分配有影响	MEUNIER et al^[27], GULA et al^[28]				北大西洋东部的海洋低氧区的形成与模态水涡旋的孤立水团输运有关		SCHüTTE et al^[35]
太平洋	在日本海观测到ITEs,被认为是由冬季混合层水沿副极地锋南边缘的锋面汇聚和俯冲作用形成的	GORDON et al^[36]	加利福尼亚潜流涡旋	加利福尼亚潜流涡旋是加利福尼亚潜流温暖、高盐水横向输送机制之一	GARFIELD et al^[37]	北太平洋次表层低位涡水团的变化和涡旋密切相关		WEN et al^[38]
			南太平洋副热带回旋的赤道13 ℃水	反气旋,可能来自于东边界的极向潜流	JOHNSON et al^[15]	北太平洋次表层低位涡水团的变化和涡旋密切相关		WEN et al^[38]
			南太平洋副热带回旋的赤道13 ℃水	反气旋,可能来自于东边界的极向潜流	JOHNSON et al^[15]	黑潮延伸体区域观测到低位涡、高溶解氧的次表层SCVs,发现它们影响中层水的俯冲		OKA et al^[41]
	利用HYCOM模拟日本海的ITEs,阐述了其生成的相关机制	HOGAN et al^[39]	黑潮延伸体涡旋	多次观测到STEs,其内部的热盐性质表明它们可能起源于黑潮上游	MAXIMENKO et al^[40], OKA et al^[41], ZHANG et al^[42]
	ITEs不仅可以离岸运输水团,还能促进上升流区域的拓展	HORMAZABAL et al^[13]	棉兰老岛海岸涡旋	多次观测到STEs,它们对南北太平洋中层的混合有重要作用	FIRING E et al^[43], CHIANG et al^[44-45], NAN et al^[46], ZHANG et al^[47]
北冰洋	早期观测到次表层SCVs的地区之一,在格陵兰海、波弗特海、拉布拉多海都曾观测到,与深对流相关(D’ASARO^[48], GASCARD et al^[49], LILLY et al^[50])

表1 在全球观测发现的典型次表层SCVs

Tab.1 Typical subsurface coherent vortices found in the global ocean

区域	温跃层内涡旋(ITEs)		温跃层下涡旋(STEs)				模态水涡旋
区域	主要结论	代表性文献	涡旋名称	主要结论	代表性文献		主要结论	代表性文献
印度洋	表层反气旋涡与热带气旋相互作用可能产生ITEs	GORDON et al^[23]	阿拉伯涡旋	阿拉伯海观测到的STEs在咸水横跨阿拉伯海的运输中具有重要作用	VIC C et al^[25], MAREZ et al^[26]
印度洋	在马达加斯加东南部观测到ITEs	NAUW et al^[24]	阿拉伯涡旋	阿拉伯海观测到的STEs在咸水横跨阿拉伯海的运输中具有重要作用	VIC C et al^[25], MAREZ et al^[26]
大西洋	综合大西洋西部永久性温跃层中等温透镜体的观测结果,解释其为孤立特征,首次提出ITEs,同时在马尾藻海中观测到ITEs	DUGAN et al^[20]	地中海涡旋	地中海涡旋将高盐的地中海水输送到亚热带大西洋,影响环流、深对流、生物化学物质等	MCDOWELL et al^[29], RICHARDSON et al^[30], BARBOSA et al^[31], BOSSE et al^[3,32-33]	模态水涡旋在大西洋西北部被观测到,它们通过沿密度面输送和动量搅拌热盐、化学物质等影响海洋环流从而影响生态		MCGILLICUDDY et al^[34]
	在副热带北大西洋东边界上升流潜流中观测到ITEs,其内部和周围生产力很高	PIETRI et al^[12]				北大西洋东部的海洋低氧区的形成与模态水涡旋的孤立水团输运有关		SCHüTTE et al^[35]
	在墨西哥湾观测到的ITEs对墨西哥湾热量、盐度再分配有影响	MEUNIER et al^[27], GULA et al^[28]				北大西洋东部的海洋低氧区的形成与模态水涡旋的孤立水团输运有关		SCHüTTE et al^[35]
太平洋	在日本海观测到ITEs,被认为是由冬季混合层水沿副极地锋南边缘的锋面汇聚和俯冲作用形成的	GORDON et al^[36]	加利福尼亚潜流涡旋	加利福尼亚潜流涡旋是加利福尼亚潜流温暖、高盐水横向输送机制之一	GARFIELD et al^[37]	北太平洋次表层低位涡水团的变化和涡旋密切相关		WEN et al^[38]
			南太平洋副热带回旋的赤道13 ℃水	反气旋,可能来自于东边界的极向潜流	JOHNSON et al^[15]	北太平洋次表层低位涡水团的变化和涡旋密切相关		WEN et al^[38]
			南太平洋副热带回旋的赤道13 ℃水	反气旋,可能来自于东边界的极向潜流	JOHNSON et al^[15]	黑潮延伸体区域观测到低位涡、高溶解氧的次表层SCVs,发现它们影响中层水的俯冲		OKA et al^[41]
	利用HYCOM模拟日本海的ITEs,阐述了其生成的相关机制	HOGAN et al^[39]	黑潮延伸体涡旋	多次观测到STEs,其内部的热盐性质表明它们可能起源于黑潮上游	MAXIMENKO et al^[40], OKA et al^[41], ZHANG et al^[42]
	ITEs不仅可以离岸运输水团,还能促进上升流区域的拓展	HORMAZABAL et al^[13]	棉兰老岛海岸涡旋	多次观测到STEs,它们对南北太平洋中层的混合有重要作用	FIRING E et al^[43], CHIANG et al^[44-45], NAN et al^[46], ZHANG et al^[47]
北冰洋	早期观测到次表层SCVs的地区之一,在格陵兰海、波弗特海、拉布拉多海都曾观测到,与深对流相关(D’ASARO^[48], GASCARD et al^[49], LILLY et al^[50])

图4 在墨西哥湾海域发现的3个温跃层内涡旋(ITE01、ITE02、ITE03)[27]

Fig.4 Three intrathermocline eddies (ITE01,ITE02, ITE03) found in the Gulf of Mexico[27]

图5 水下滑翔机观测在地中海海域发现的温跃层下涡旋[3] [a:盐度剖面,图中白色等值线为等密度线;b:垂直于水下滑翔机测线的流速剖面(蓝色虚线框内为梯度风流速,蓝色虚线框外为地转流速),图中叠加了较大流速等值线(白色线)和平滑的等密度线(黑色线),蓝色虚线框为涡旋范围。]

Fig.5 Subthermocline eddies found in Mediterranean Sea by the underwater glider[3] [a: Salinity section with density contours in white; b: Cross-section velocities (Cyclostrophic within the blue box and geostrophic outside). The large current speed contours (white contours) are overlaid, and the black contours show the smoothed density field. Blue dashed box indicates eddy interior.]

图6 次表层模态水涡旋捕获流体的示意图[21] (图中颜色和黑色等值线表示等密度面上的位涡分布,黑色透明面为最外层封闭等位涡线的闭合面。)

Fig.6 Schematic diagram of trapped fluid by the subsurface modal water eddy[21] (The potential vorticity distributions on isopycnals are depicted by colored and black contours. The transparent black surface, defined by the outmost closed potential vorticity contours.)

图7 1997年8月—2020年1月基于Argo浮标识别出的所有次表层SCVs的分布[19] (红色点表示高涩度中心次表层SCVs,蓝色点表示低涩度中心次表层SCVs。)

Fig.7 Distribution of all subsurface coherent vortices detected from Argo buoys during August 1997 to January 2020[19] (In the figure, red dots are the subsurfacec coherent vortexes with the high spicy center, and blue dots are the subsurface coherent vortexes with the low spicy center.)

图8 锋面区模态水俯冲生成次表层SCVs示意图[52]

Fig.8 Schematic diagram of subsurface vortex formed by modal water subduction in frontal zone[52]

图9 海流流过海底地形通过摩擦力矩作用生成次表层SCVs示意图

Fig.9 Schematic diagram of subsurface vortex formed by flowing through terrain by friction torque

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