The Kuroshio flow-through in the East China Sea : A numerical model

• Published in: Progress in oceanography Vol. 39; no. 2; pp. 79 - 108
• Main Authors: HSUEH, Y, SCHULTZ, J. R, HOLLAND, W. R
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier 1997
• Subjects: Earth, ocean, space; Exact sciences and technology; External geophysics; Marine; Physics of the oceans; Thermohaline structure and circulation. Turbulence and diffusion; Kuroshio; Pacific Ocean; East China Sea; North Pacific; INW, Pacific, Kuroshio Current; INW, Donghai Sea; INW, Donghai Sea, Kuroshio Current; Temperature; Stream function; General circulation models; Ocean circulation; Flow(fluid); Numerical simulation; Slope current; Ocean model; Salinity
• ISSN: 0079-6611; 1873-4472
• DOI: 10.1016/s0079-6611(97)00008-6

The Bryan-Cox model of general ocean circulation is adapted to the East China Sea to study the flow-through of the Kuroshio. The model domain lies between 22 degree N and 35 degree N and between 119 degree E and 135 degree E, with a horizontal grid size of 1/6 degree and a vertical resolution provided by 30 levels so placed as to represent adequately the rapid change in bottom topography over the upper continental slope that underlies the Kuroshio. The model is driven by a steady inflow and outflow consistent with the Sverdrup transport calculated from the annual mean windstress field over the entire North Pacific. Temperature and salinity at the model sea surface are relaxed to the climatological values on a 50-day time scale. There is no locally imposed windstress. The model is initialized with the inflow-and-outflow-forced streamfunction field and climatological fields of temperature and salinity. The outflow condition is subsequently updated to reflect the redistribution suggested by the adjusted interior during the first year of integration. The model is then run with a combination of relaxation and radiation conditions along open boundaries for a total of six years, nearly five years beyond the time when the basin averaged kinetic energy reaches a constant value. In the final quasi-steady state, the model exhibits many of the patterns evident in observations, including a sharpened Kuroshio front over the upper continental slope, the countercurrent at about 200 m northeast of Taiwan, and the separation of the Kuroshio at about 30 degree N. A budget calculation at the final state shows that about 5% of the net poleward heat transport carried by the Kuroshio across 24 degree N in the North Pacific is routed through the marginal seas. Similarly, a salt flux about 5% of the net poleward transport carried by the Kuroshio across 24 degree N is directed to the north into the Sea of Japan, making the East China Sea an important salt source for water mass formation at high latitudes in the North Pacific Ocean.