Formation of an anticyclonic eddy and the mechanism involved: a case study using cruise data from the northern South China Sea -- Journal of Oceanology and Limnology,2019,37(5):1481-1494

	Cite this paper:
	HOU Huaqian, XIE Qiang, XUE Huijie, SHU Yeqiang, NAN Feng, YIN Yuqi, YU Fei. Formation of an anticyclonic eddy and the mechanism involved: a case study using cruise data from the northern South China Sea[J]. Journal of Oceanology and Limnology, 2019, 37(5): 1481-1494

Formation of an anticyclonic eddy and the mechanism involved: a case study using cruise data from the northern South China Sea

HOU Huaqian^1,2, XIE Qiang^1,3, XUE Huijie^1,4, SHU Yeqiang^1,5, NAN Feng², YIN Yuqi², YU Fei²

1 State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China;
2 Key Laboratory of Ocean Circulation and Wave Studies, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China;
3 Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences, Sanya 572006, China;
4 School of Marine Sciences, University of Maine, Orono 04469, Maine, USA;
5 Innovation Academy of South China Sea Ecology and Environmental Engineering, Chinese Academy of Science, Guangzhou 510301, China

Abstract:

Data from satellite altimetry and in situ observations together with the Hybrid Coordinate Ocean Model (HYCOM) reanalysis data were used to investigate the mechanism and formation of an anticyclonic eddy in the northeastern South China Sea (SCS). Analysis of water mass using cruise data indicated that the water captured in the eddy differs from those in the SCS, the Kuroshio intrusion, and the eddy-forming region. Data from sea surface height (SSH) and sea level anomaly (SLA) indicate that the eddy formed due both to the Kuroshio intrusion and the local circulation in the SCS. The Kuroshio intrusion is present at the start of the eddy growth (March 5-9) before Kuroshio leaps the Luzon Strait. The eddy then becomes larger and stronger in the absence of the Kuroshio intrusion. From the eddy budget of the HYCOM reanalysis data, the formation of the eddy goes in three steps. By the third step, the eddy had become affected by variations of local SCS circulation, which is more strongly than in the first step in which it is affected more by the Kuroshio intrusion. The variability of the temperature and salinity inside the eddy provide a support to this conclusion. The water in the SCS intruded into the eddy from the southeast, which decrease the salinity gradually in the southern part of the eddy during the growth period.

Key words: anticyclonic eddy|Kuroshio intrusion|circulation variation|water mass

Received: 2018-10-19 Revised: 2018-12-17

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