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FENG Ying,CHEN Xianyao,WANG Qin,YUAN Yeli. 2015. Mesoscale characteristics of Antarctic Intermediate Water in the South Pacific. Acta Oceanologica Sinica, 34(11):92-101
Mesoscale characteristics of Antarctic Intermediate Water in the South Pacific
南太平洋南极中层水的中尺度特征
Received:March 19, 2015  Revised:June 02, 2015
DOI:10.1007/s13131-015-0752-2
Key words:mesoscale characteristics  subsurface ocean  Antarctic Intermediate Water (AAIW)  Argo
中文关键词:  中尺度特征  次表层海洋  南极中层水  ARGO漂流浮标
基金项目:The National Natural Science Foundation of China under contract No. 41176029; the Basic Scientific Fund for National Public Research Institute of China under contract No. GY02-2012G25.
Author NameAffiliationE-mail
FENG Ying College of Ocean and Earth Sciences, Xiamen University, Xiamen 361002, China fengying@stu.xmu.edu.cn 
CHEN Xianyao Key Laboratory of Physcial Oceanography, Ocean University of China, Qingdao 266100, China  
WANG Qin Marine Monitoring and Forecasting Center of Zhejiang, Hangzhou 310007, China  
YUAN Yeli Key Laboratory of Marine Science and Numerical Modeling, the First Institute of Oceanography, State Oceanic Administration, Qingdao 266061, China  
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Abstract:
      The Argo float observations are used to investigate the mesoscale characteristics of the Antarctic Intermediate Water (AAIW) in the South Pacific in this paper. It is shown that a subsurface mesoscale phenomenon is probably touched by an Argo float during the float's ascent-descent cycles and is identified by the horizontal salinity gradient between the vertical temperature-salinity profiles. This shows that the transportation of the AAIW may be accompanied with the rich mesoscale characteristics. To derive the spatial length, time, and propagation characteristics of the mesoscale variability of the AAIW, the gridded temperature-salinity dataset ENACT/ENSEMBLE Version 3 constructed on the in-situ observations in the South Pacific since 2005 is used. The Empirical Mode Decomposition method is applied to decompose the isopycnal-averaged salinity anomaly from 26.8 σθ-27.4 σθ, where the AAIW mainly resides, into the basin scale and two mesoscale modes. It is found that the first mesoscale mode with the length scale on the order of 1 000 km explains nearly 50% variability of the mesoscale characteristics of the AAIW. Its westward-propagation speeds are slower in the mid-latitude (around 1 cm/s) and faster in the low latitude (around 6 cm/s), but with an increasing in the latitude band on 25°-30°S. The second mesoscale mode is of the length scale on the order of 500 km, explaining about 30% variability of the mesoscale characteristics of the AAIW. Its westward-propagation speed keeps nearly unchanged (around 0.5 cm/s). These results presented the stronger turbulent motion of the subsurface ocean on the spatial scale, and also described the significant role of Argo program for the better understanding of the deep ocean.
中文摘要:
      本文利用ARGO漂流浮标观测资料分析南大洋南极中层水(AAIW)的中尺度特征.研究表明次表层中尺度现象很有可能被在海洋中上下运动的ARGO漂流浮标捕捉到,并且通过垂向温盐剖面中水平的盐度梯度可以辨认出来.南大洋南极中层水输运的过程中可能携带着非常丰富的中尺度特征.为了得到南极中层水中尺度变异的空间尺度、持续时间和传播特性,我们利用基于现场观测的网格化ENACT/ENSEMBLE 3温度-盐度数据,并用经验模分解方法处理平均等密度面上的在26.8-27.4之间的盐度异常,将南极中层水分解成一个海盆尺度模态和两个中尺度模态.经研究发现,南极中层水的第一个中尺度模态的空间尺度是1000km量级,可以解释近50%的中尺度变异.它的西向传播速度在中纬度相对较低,只有1cm/s左右,而在低纬度地区传播速度却很快,接近6cm/s,然而在25°-30°S也出现了快速的增长.第二个中尺度模态的空间尺度在500km量级,能够解释大概30%的南极中层水的中尺度变异.西向传播速度随着纬度变化很小,都在0.5cm/s左右.这些研究结果表明,在大洋次表层中存在更强的湍流作用,同时也说明ARGO计划对于深海研究有着深远的意义.
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