Three‐dimensional pathways of water masses in the South China Sea: A modeling study. Issue 7 (28th July 2017)

• Record Type: Journal Article
• Authors: Liu, Zhiqiang; Gan, Jianping
• Is Part Of: Journal of geophysical research. Volume 122:Issue 7(2017)
• Page Start: 6039
• Page End: 6054
• Publication Date: 2017-07-28
• Subjects: South China Sea circulation -- pathways of water masses -- residence time -- numerical simulation; Oceanography -- Periodicals; 551.4605
• DOI: 10.1002/2016JC012511
• Languages: English
• ISSNs: 2169-9275

Abstract

Abstract: We conduct a numerical Eulerian analysis on the Lagrangian characteristics of South China Sea (SCS) water masses. This is the first study to investigate the water pathway and residence time in response to time‐dependent, three‐dimensional basin circulation in the SCS. The circulation of the SCS is largely determined by westward intrusions of the northwestern Pacific waters in the upper layer (0–750 m) and deep layer (>1500 m), and by an eastward extrusion in the intermediate layer (750–1500 m) through Luzon Strait (LS). The waters in these three layers are interlinked to sustain the three‐dimensional circulation in the SCS. The upper intrusive waters flow cyclonically and have a residence time of ∼3 years before they subduct into a deeper layer or exit the SCS through surrounding straits. The intrusive denser waters in the deep layer flow along the northern slope and reside for ∼25 years in the northern basin (north of 13°N), where a strong subduction occurs. A cyclonic circulation exists in the deep layer in the southern basin (south of 13°N), where a subduction of intermediate waters occurs over its eastern side and a deep upwelling exists over its western side. The water in the deep southern basin has a residence time of ∼40 years. The upwelled deep waters and the subducted waters from the upper layer form the intermediate water, where waters circulate anti‐cyclonically toward LS and have a longest residence time (∼42 years). These findings are supported by the spatial variation in the observed potential density variance. Key Points: The pathway of the SCS waters is determined not only by exchange with the neighboring oceans, but also by exchange between different layers The residence time (ReT) of SCS waters generally increases southward and downward, and the longest ReT (∼42 years) exists in the intermediate layer The refreshment of deep waters in the basin is governed by an extensive cyclonic circulation in the southern South China Sea (south of 13°N)