Subsurface high salinity (>34.68‰) is often used as an indicator of the North Pacific Tropical Water (NPTW). It is also used as an indicator of the Kuroshio intrusion into the South China Sea (SCS). It is used here to investigate water exchange between the SCS and the northwestern Pacific. Using high-resolution hybrid coordinate ocean model (HYCOM) global assimilation data, we investigate seasonal variation of subsurface high salinity water in the northern SCS and the influence from the northwestern Pacific. Results show that there exists obviously seasonal variation in the subsurface high salinity water at about 100~200 m depth, reaching as far west as 111°E in the northern SCS, and the salinity reaches its maximum (minimum) in December (June). Further analysis shows that the seasonal change of high salinity water is strongly affected by the seasonal variation of large-scale circulation in the low latitude northwestern Pacific. The volume changes of the high salinity water is highly correlated with the bifurcation latitude of the North Equatorial Current (NEC), which reaches northernmost latitude in January and southernmost latitude in June. Due to the large-scale wind change in the Pacific, the Kuroshio transport strengthens (weakens) when the bifurcation latitude of the NEC shifts to the south (north) during the first (second) half year, the salinity flux diminishes (increases) from upper northwestern Pacific into the SCS through the Luzon Strait, and the intrusion of the subsurface high salinity water in the northern SCS weakens (enhances). The velocity and salinity flux distribution in the Luzon Strait show that the high salinity water mainly enters the northern SCS between 20°~21°18°N.
WANG Ai-mei
,
DU Yan
,
ZHUANG Wei
,
WANG Fa-yun
,
QI Yi-quan
. The seasonal variation of subsurface high salinity in the northern South China Sea and its relationship to the northwestern Pacific circulations[J]. Journal of Tropical Oceanography, 2014
, 33(6)
: 1
-8
.
DOI: 10.11978/j.issn.1009-5470.2014.06.001
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