Characteristics and mechanism of ocean subsurface coherent eddies: Problems and progress

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

Abstract

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

CLC Number:

P731.2

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.

Figures/Tables 10

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].]

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

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

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])

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])

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

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.]

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.)

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.)

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

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

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