摘要
根据维基百科的定义(https:∥en.wikipedia.org/wiki/Edd),海洋中水平直径在10~500km、持续时间由数天至数月之间的水平旋转水体通称为中尺度涡。南海中尺度涡最早发现于1956年,60a来的观测与研究表明,南海是中尺度涡多发、频发海区。南海中尺度涡研究大致经历了早期发现、将中尺度涡当作单体运动现象研究、统计分析和当作群体运动现象研究等阶段,本文概要评述南海中尺度涡研究发展史和近年最新研究进展。经过60a的观测与研究,南海中尺度涡的宏观特征,包括三维结构和运动学,已大致清楚。南海中尺度涡全年皆可发生,主要分布在水深大于1 000m的深海盆,其中吕宋海峡以西和海盆西边界最为集中,气旋式冷涡和反气旋式暖涡发生概率大致相同。南海中尺度涡海面半径大多分布在50~150km,半径随水深减小,平均水平尺度比太平洋的涡旋要小。涡旋个数逐月变化,但季节规律不明显;年际变化幅度约20%,但与ENSO无明显对应关系;年平均个数的统计结果不一,最少11个·a^(-1),最多49个·a^(-1)。南海中尺度涡旋转流场从表层一直延伸到海底,流矢量表层(100m)最大(可达40cm·s^(-1)),随水深减小,2 000m仍可达3.5~5.0cm·s^(-1),但相对涡旋中心不对称,涡轴线向西倾斜。南海中尺度涡以2.0~9.0cm·s^(-1)的速度向西传播,低速区分布在深海盆东边界和西南部分海域。海面涡度平均值在5.4×10^(-6)~20×10^(-6) s^(-1)区间,高于太平洋平均值。近期研究把南海中尺度涡视为群体运动现象,先后提出长寿涡列、驻波模态和罗斯贝标准模等新概念。关于南海中尺度涡的发生机制,前人多认为黑潮和南海局地为起源。最新观点认为以罗斯贝波和中尺度涡为表现形式的太平洋中尺度扰动直接进入南海,并与海盆固有振荡模态发生共振,从而构成太平洋起源。而南海中尺度涡耗散过程、中尺度涡与其他海洋过程的相互作用有待进一步研究。
According to Wikipedia (https:∥en.wikipedia.org/wiki/Eddy),mesoscale eddies in the ocean are rotating water masses with diameters between about 10 and 500 km and lifetime from days to months.Mesoscale eddies in the South China Sea (SCSME) were firstly observed in 1956.Since then,60-years of observations and investigations have shown that the SCS are a unique ocean area with energetic and high-frequency occurred mesoscale eddies.The research of SCSME has passed stages of early discovery,being studied as a single water mass motion and as grouped water mass motion.This paper reviews the development history and new progress in the research of SCSME.By 60-years of observations and investigations,general characteristics of SCSME,such as the 3D structure and the kinematics,have been mostly revealed.SCSME may occur all year around.They are mainly distributed in the deep basin with the water depth deeper than 1 000 m,in particular concentrated in the west of the Luzon Strait and the western boundary of the basin.The occurrence frequencies of cyclonic eddies and anticyclonic eddies are near the same.The sea surface radiuses of SCSME are mostly distributed with a range from 50 to 150 km.The radius decreases with the water depth.The average horizontal scale of SCSME is smaller than that in the Pacific.The number of SCSMEs has monthly variation,but not obvious seasonal variation.The amplitude of annual variation is about 20%,but correspondence to the ENSO events is not supported by the observations.The statistical results of annual number of SCSMEs are inconsistent.The minimum number is 11 per year,and the maximum is 49 per year.The rotating current field of SCSME extends from the sea surface to the bottom.The current vector reaches the maximum value of 40 cm·s^-1 at the surface layer of 100 m,decreases with the water depth to 3.5-5.0 cm·s^-1 at 2 000 m.SCSMEs propagate westward with velocities from 2.0 to 9.0 cm·s^-1,and the low velocity areas are distributed in the eastern boundary of the deep basin and the southwestern SCS.The mean value of the sea surface vorticity of SCSMEs is within a range from 5.4×10-6 to 20×10^-6 s^-1,higher than that in the Pacific.Recent investigations treat SCSME as a grouped motion phenomenon,and have proposed new concepts of long-lived eddy row,standing wave modes and the Rossby normal modes.Of the generation mechanisms,previous investigators have suggested the Kuroshio origin and the SCS local origins.The newest point-of-view suggests that disturbance from the Pacific in the form of the Rossby waves and eddies may enter the SCS directly and resonance with intrinsic oscillation modes of the basin,so that forms another Pacific origin.In addition,the dissipation processes and the interaction of SCSMEs with other ocean processes are worth further pursuing.
作者
郑全安
谢玲玲
郑志文
胡建宇
ZHENG Quan-an XIE Ling-ling ZHENG Zhe-wen HU Jian-yu(Department of Atmospheric and Oceanic Science ,University of Maryland ,College Park, Maryland 20742, USA College of Ocean and Meteorology ,Guangdong Ocean University ,Zhanjiang 524088,China The First Institute of Oceanography ,Sate Oceanic Administration, Qingdao 266061 ,China National Taiwan Normal University, Taipei 10610,China College of Ocean and Earth Sciences, Xiamen University, Xiamen 361005, China)
出处
《海洋科学进展》
CAS
CSCD
北大核心
2017年第2期131-158,共28页
Advances in Marine Science
基金
国家自然科学基金项目--热带气旋对琼东上升流动力过程和物质输送的影响机制研究(41476009)
台湾海峡与吕宋海峡水体交换及相互作用研究(U1405233)
广东省高等学校优秀青年教师项目--粤西陆架环流的调控机制研究(YQ2015088)
广东海洋大学创新强校项目--热带气旋对上升流动力过程的影响机制(GDOU2016050240)
关键词
南海
中尺度涡
长驻涡列
驻波模态
罗斯贝标准模态
South China Sea
mesoscale eddies
long lived eddy row
standing wave modes
Rossby normal modes