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Huang Runqi,Xie Lingling,Zheng Quanan,Li Mingming,Bai Peng,Tan Keyi. 2020. Statistical analysis of mesoscale eddy propagation velocity in the South China Sea deep basin. Acta Oceanologica Sinica, 39(11):91-102
Statistical analysis of mesoscale eddy propagation velocity in the South China Sea deep basin
南海海盆中尺度涡移动速度统计分析
Received:June 15, 2020  
DOI:10.1007/s13131-020-1678-x
Key words:South China Sea  mesoscale eddies  eddy propagation velocity  variation in life span  eddies with abnormal speeds
中文关键词:  南海  中尺度涡  涡旋移动速度  生命周期内变化  移速异常涡旋
基金项目:The National Natural Science Foundation of China under contract Nos 41776034 and 41706025; the Fund of Southern Marine Science and Engineering Guangdong Laboratory (Zhanjiang) under contract No. ZJW-2019-08; the Special Project of Global Change and Air and Sea Interaction under contract No. GASI-02-SCS-YGST2-02; the Guangdong Province First-Class Discipline Plan under contract Nos CYL231419012 and 231389002; the Scientific Research Setup Fund of Guangdong Ocean University under contract No.101302/R18001.
Author NameAffiliationE-mail
Huang Runqi Laboratory of Coastal Ocean Variation and Disaster Prediction, College of Ocean and Meteorology, Guangdong Ocean University, Zhanjiang 524088, China  
Xie Lingling Laboratory of Coastal Ocean Variation and Disaster Prediction, College of Ocean and Meteorology, Guangdong Ocean University, Zhanjiang 524088, China
Marine Resources Big Data Center of South China Sea, Southern Marine Science and Engineering Guangdong Laboratory (Zhanjiang), Zhanjiang 524025, China 
xiell@gdou.edu.cn 
Zheng Quanan Department of Atmospheric and Oceanic Science, University of Maryland, College Park, Maryland 20742, USA  
Li Mingming Laboratory of Coastal Ocean Variation and Disaster Prediction, College of Ocean and Meteorology, Guangdong Ocean University, Zhanjiang 524088, China
Marine Resources Big Data Center of South China Sea, Southern Marine Science and Engineering Guangdong Laboratory (Zhanjiang), Zhanjiang 524025, China 
 
Bai Peng Laboratory of Coastal Ocean Variation and Disaster Prediction, College of Ocean and Meteorology, Guangdong Ocean University, Zhanjiang 524088, China
Marine Resources Big Data Center of South China Sea, Southern Marine Science and Engineering Guangdong Laboratory (Zhanjiang), Zhanjiang 524025, China 
 
Tan Keyi Laboratory of Coastal Ocean Variation and Disaster Prediction, College of Ocean and Meteorology, Guangdong Ocean University, Zhanjiang 524088, China  
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Abstract:
      Using mesoscale eddy trajectory product derived from satellite altimetry data from 1993 to 2017, this study analyzes the statistical characteristics of spatiotemporal distribution of mesoscale eddy propagation velocities (C) in the South China Sea (SCS) deep basin with depths >1 000 m. Climatologically, the zonal propagation velocities (cx) are westwards in the whole basin, and the meridional velocities (cy) are southwards in the northwestern basin, and northwards in the southeastern basin. The variation of cy with longitude is consistent with that of the background meridional currents with correlation coefficient R2 of 0.96, while the variation of cx is related both to the background zonal currents and β effect. The propagation velocities characterize significant seasonality with the minimum magnitude occurring in summer and the maximum in winter for cx and C. Interannually, larger values of cx and cy mostly occurred in La Niña years in the negative phase of the Pacific Decadal Oscillation (PDO). Mesoscale eddies move fast at the beginning and end of their life span, i.e., at their growth and dissipation periods, and slowly during their stable “midlife” period. This trend is negatively correlated with the rotating tangential velocity with R2 of –0.93. Eddies with extreme propagation velocities are defined, which are slower (faster) than 1.5 cm/s (15.4 cm/s) and take 1.5% (1.9%) of the total eddies. The extremely slow-moving (fast-moving) eddies tend to appear in the middle (on the edge) of the basin, and mostly occur in summer (winter). The mechanism analysis reveals that the spatiotemporal distributions of the propagation velocities of mesoscale eddies in the SCS are modulated by the basin-scale background circulation.
中文摘要:
      基于1993-2017年卫星高度计数据得到的中尺度涡追踪产品,分析了1000 m以深南海海盆中尺度涡移动速度C的时空分布特征。结果表明,南海海盆气候态平均的中尺度涡纬向移动速度cx均为西向,经向移动速度cy在海盆西北侧为南向,东南侧为北向。cy随经度的变化与背景经向流的变化一致,相关系数达0.96,而cx的变化与背景纬向流和β效应有关。cxC存在明显季节变化,夏季最慢,冬季最快。年际变化上,cxcy的大值多发生在太平洋年代际涛动(PDO)负位相期的La Nina年。中尺度涡在其生命周期的开始和结束阶段(即生成和耗散阶段)移速较快,而在稳定的“中期”阶段移动缓慢。该趋势与涡旋转速呈反相关,相关系数为-0.93。以移速小于1.5 cm/s和大于15.4 cm/s定义的极慢和极快涡旋,分别占总涡旋数量的1.5%和1.9%。移速极慢的涡多出现在海盆的中部,且主要发生在夏季;移速极快的涡多出现在海盆的边缘,且主要发生在冬季。机制分析显示,南海海盆中尺度涡移动速度的时空分布受到大尺度背景流场调制。
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