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LI Bo, YUAN Dongliang, ZHOU Hui. Water masses in the far western equatorial Pacific during the winters of 2010 and 2012[J]. Journal of Oceanology and Limnology, 2018, 36(5): 1459-1474

Water masses in the far western equatorial Pacific during the winters of 2010 and 2012

LI Bo1,4,5, YUAN Dongliang1,2,3, ZHOU Hui1
1 Key Laboratory of Ocean Circulation and Waves, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China;
2 Function Laboratory for Ocean Dynamics and Climate, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266000, China;
3 Qingdao Collaborative Innovation Center of Marine Science and Technology, Qingdao 266000, China;
4 State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China;
5 University of the Chinese Academy of Sciences, Beijing 100049, China
Conductivity-temperature-depth (CTD) data obtained during the 2010 La Niña winter and the 2012 normal winter, combined with concurrent Argo profiling float data, provide a quasi-synoptic description of the water mass distributions and their variations in the far western equatorial Pacific Ocean. The water mass connection between the western Pacific and the east Indonesian seas is emphasized. Analysis indicates that the North Pacific Tropical Water (NPTW, S>34.9) carried by the Mindanao Current southward and the South Pacific Tropical Water (SPTW, S>35.1) from the southern hemisphere meet in the area. Observations suggest that the southward transport of the NPTW is stronger in 2010 than in 2012 due to enhanced advection of the Mindanao Current. The distribution of SPTW, which crosses the equator in the northwest direction and retroflects back to the interior Pacific Ocean, is found to retreat from 4°-5°N in 2012 to 2°-3°N in 2010 La Niña peak in the 130°E section. A relatively fresh tropical subsurface water is identified in between the NPTW and the SPTW, moving eastward with the North Equatorial Countercurrent into the equatorial Pacific Ocean. However, the salinity maximum of this subsurface fresh water is found to decrease eastward, suggesting that the salinity maximum is generated either by strong diapycnal mixing or by isopycnal mixing of temporally entrained Indonesian sea water into the area.
Key words:    far western equatorial Pacific|North Pacific Tropic Water|South Pacific Tropical Water|tropical subsurface water|La Niña   
Received: 2017-03-10   Revised:
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