Cold deep water in the South China Sea
Journal
Journal of Oceanography
Journal Volume
66
Journal Issue
2
Pages
183-190
Date Issued
2010
Author(s)
Abstract
Two deep channels that cut through the Luzon Strait facilitate deep (>2000 m) water exchange between the western Pacific Ocean and the South China Sea. Our observations rule out the northern channel as a major exchange conduit. Rather, the southern channel funnels deep water from the western Pacific to the South China Sea at the rate of 1.06 ± 0.44 Sv (1 Sv = 106 m3s-1). The residence time estimated from the observed inflow from the southern channel, about 30 to 71 years, is comparable to previous estimates. The observation-based estimate of upwelling velocity at 2000 m depth is (1.10 ± 0.33) × 10-6 ms-1, which is of the same order as Ekman pumping plus upwelling induced by the geostrophic current. Historical hydrographic observations suggest that the deep inflow is primarily a mixture of the Circumpolar Deep Water and Pacific Subarctic Intermediate Water. The cold inflow through the southern channel offsets about 40% of the net surface heat gain over the South China Sea. Balancing vertical advection with vertical diffusion, the estimated mean vertical eddy diffusivity of heat is about 1.21 × 10-3 m2s-1. The cold water inflow from the southern channel maintains the shallow thermocline, which in turn could breed internal wave activities in the South China Sea. © Springer Science+Business Media B.V. 2010.
SDGs
Type
journal article