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General Session 1: Physical oceanic processes: Dynamics and physical-biological-biogeochemical interactions |
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A peculiar lens-shaped structure observed in the South China Sea
Monday 9th @ 1605-1620
Conference Hall
Hongyang Lin* , Xiamen University
Jianyu Hu, Xiamen University
Zhiyu Liu, Xiamen University
Igor M. Belkin, University of Rhode Island
Zhenyu Sun, Xiamen University
Presenter Email: hylin@xmu.edu.cn
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| Lens-shaped structures within thermocline potentially play a significant role in subsurface transport of mass, heat, and salt in the global ocean. Whilst such structures have been observed in many oceanic regions, none has been documented in the China seas. This study reports on observations of a lens-shaped structure within thermocline in the southwestern South China Sea (SCS) in September 2007. This structure has a maximum thickness of approximately 60 m and a horizontal extent exceeding 220 km. This lens is peculiar in the sense that its size is larger than most similar structures documented in the literature. The lens core is characterized by relatively well-mixed water with higher temperature (~28.8ˇăC) and lower salinity (~33.3) compared to the surrounding waters, and more importantly by low potential vorticity (PV). Diagnostic analysis of vertical PV flux and the evolution of surface density field suggest a coastal jet separation site as the origin. It is proposed that the frontal water subducted along outcropped isopycnals forms the observed lens-shaped structure under the combined influences of ˇ°down-frontˇ± monsoon winds and a frontogenesis process. Given the possible recurrence of such subsurface structures, they might also have broader biogeochemical implications (e.g., carbon sequestration) in the SCS. |
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