Origin of the springtime South China Sea Warm Current in the southwestern Taiwan Strait: Evidence from seawater oxygen i
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tober 2020 Vol.63 No.10: 1564–1576 https://doi.org/10.1007/s11430-019-9642-8
Origin of the springtime South China Sea Warm Current in the southwestern Taiwan Strait: Evidence from seawater oxygen isotope 1†
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Dongyu CHEN , Ergang LIAN , Yeqiang SHU , Shouye YANG , Yalong LI , Chao LI , 1 1 Pengfei LIU & Ni SU 1
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State Key Laboratory of Marine Geology, Tongji University, Shanghai 200092, China; State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China Received December 6, 2019; revised March 29, 2020; accepted June 5, 2020; published online August 18, 2020
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Abstract Oxygen isotope (δ O) of seawater is an excellent proxy for tracing the origins of water masses and their mixing processes. Combining with hydrographic observation, hybrid coordinate ocean model (HYCOM) analysis data, and seawater oxygen isotope, we investigated the source of the South China Sea Warm Current (SCSWC) in the southwestern Taiwan Strait and its underlying mechanism. Results show that the Kuroshio subsurface water (KSSW) can intrude the continental slope in the 18 southwestern Taiwan Strait, and thereby climb up the continental slope coupled with upwelling. The δ O-salinity relationship further indicates that in spring, the SCSWC in the southwestern Taiwan Strait originates from the upslope deflection of the slope current formed by the KSSW intrusion into the South China Sea, rather than from the west segment of the SCSWC formed to the east of Hainan Island. In addition, the southward flowing Zhe-Min Coastal Current (ZMCC) can reach as far as the Taiwan Bank (TB) and deflects offshore over the western TB at approximately 23.5°N, to some extent affecting the SCSWC. Moreover, this 18 study reveals that seawater δ O is exquisitely sensitive to the determination of the origin and transport of water masses as compared with traditional potential temperature-salinity plot (θ-S) and HYCOM analysis data. In addition, their coupling can more reliably interpret the mixing processes of shelf water masses. Keywords Oxygen isotope, South China Sea Warm Current, Zhe-Min Coastal Current, Kuroshio, Southwestern Taiwan Strait Citation:
Chen D, Lian E, Shu Y, Yang S, Li Y, Li C, Liu P, Su N. 2020. Origin of the springtime South China Sea Warm Current in the southwestern Taiwan Strait: Evidence from seawater oxygen isotope. Science China Earth Sciences, 63: 1564–1576, https://doi.org/10.1007/s11430-019-9642-8
1. Introduction The southwestern Taiwan Strait bears an important channel, namely the Taiwan Strait, between the East China Sea (ECS) and the South China Sea (SCS). It has the SCS Basin to the south and borders the Luzon Strait and the Western Pacific in the east. With a well-developed broad continental shelf and a * Corresponding author (email: [email protected]) † Contributed equally to this work
steep continental slope, the southwestern Taiwan Strait is one of the most important fishing grounds in China (Figure 1a). Affected by factors such as to
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