Research Article
Observations of an Extra-Large Subsurface Anticyclonic Eddy in the Northwestern Pacific Subtropical Gyre
Feng Nan1, Fei Yu1,2*, Chuanjie Wei1, Qiang Ren1 and Conghui Fan11Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China
2University of Chinese Academy of Sciences, Beijing, China
- Corresponding Author:
- Dr. Fei Yu
Institute of Oceanology
Chinese Academy of Sciences
7 Nanhai Road, Qingdao 266071, China
Tel: (86)053282898187
Fax: (86)053282898186
E-mail: yuf@qdio.ac.cn
Received Date: July 05, 2017; Accepted Date: July 26, 2017; Published Date: July 30, 2017
Citation: Feng Nan, Yu F, Wei C, Ren Q, Fan C (2017) Observations of an Extra-Large Subsurface Anticyclonic Eddy in the Northwestern Pacific Subtropical Gyre. J Marine Sci Res Dev 7:234. doi: 10.4172/2155-9910.1000234
Copyright: © 2017 Feng Nan, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Abstract
An extra-large subsurface anticyclonic eddy (SAE) with horizontal scale of 470 km was detected in the northwestern Pacific subtropical gyre by in situ measurements in October 2014. The SAE exhibited a lens-shaped vertical structure with shoaling of the seasonal thermocline and deepening of the main thermocline. Consequently, the water in the eddy core was colder above 200 m and warmer below 200 m than the surrounding waters with maximum temperature anomalies of -1.2°C and 3.5°C located at ~100 m and ~450 m depths, respectively. The central water mass of the SAE was characterized as low potential vorticity water, i.e., the north Pacific Subtropical Mode Water (STMW). Swirl velocity of the SAE was directly observed by ship-mounted ADCP (Acoustic Doppler Current Profilers). The maximum azimuthal velocity reached 0.35 ms-1 near a 110 km radius at ~ 200 m depth, which was comparable with the maximum velocity of the northward Kuroshio east of Taiwan at the same depth. Threedimensional structure and evolutionary process of the SAE were also presented using Argo float profile data as well as the satellite altimeter data. The results indicated that the SAE was generated in the region of the STMW in February, then propagated westward over 1500 km at a mean speed of ~0.06 ms-1 and finally disappeared east of Taiwan in December, transporting ~0.5 Sv (Sv=106 m3s-1) STMW.
