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Journal of Oceanography

, Volume 57, Issue 5, pp 549–563 | Cite as

Low Salinity, Cool-Core Cyclonic Eddy Detected Northwest of Luzon during the South China Sea Monsoon Experiment (SCSMEX) in July 1998

  • Peter C. Chu
  • Chenwu Fan
Article

Abstract

To detect eddies, intensive surveys of the northeast South China Sea (SCS) (114°30′–121°30′ E, 17°–22°N) were conducted in July 1998 during the international SCS Monsoon Experiment (SCSMEX), the U.S. Navy using Airborne Expendable Bathythermograph and Conductivity-Temperature-Depth sensors (AXBT/AXCTD), and the Chinese Academy of Sciences using Acoustic Doppler Current Profilers (ADCP). The hydrographic survey included 307 AXBT and 9 AXCTD stations, distributed uniformly throughout the survey area. The ADCP survey had two sections. The velocity field inverted from the AXBT/AXCTD data and analyzed from the ADCP data confirm the existence of a low salinity, cool-core cyclonic eddy located northwest of Luzon Island (i.e., the Northwest Luzon Eddy). The radius of this eddy is approximately 150 km. The horizontal temperature gradient of the eddy increases with depth from the surface to 100 m and then decreases with depth below 100 m. The cool core was evident from the surface to 300 m depth, being 1°–2°C cooler inside the eddy than outside. The tangential velocity of the eddy is around 30–40 cm/s above 50 m and decreases with depth. At 300 m depth, it becomes less than 5 cm/s.

Mesoscale eddies South China Sea Monsoon Experiment (SCSMEX) P-vector method airborne expendable bathythermograph (AXBT) airborne expendable CTD (AXCTD) 

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Copyright information

© The Oceanographic Society of Japan 2001

Authors and Affiliations

  • Peter C. Chu
    • 1
  • Chenwu Fan
    • 1
  1. 1.Department of OceanographyNaval Postgraduate SchoolMontereyU.S.A

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