• Fisheries and Aquatic Sciences
• /
• v.4 no.3
• /
• pp.101-111
• /
• 2001

In an attempt to demonstrate the seasonal variation of the Ulleung Warm Eddy (UWE), in which the UWE changes its shape from a warm core ring in early spring to a warm lens in late summer under the effect of surrounding East Korean Warm Current (EKWC) Water, a simple geostrophic adjustment model is considered. Model results indicate that the buoyancy increase of the EKWC Water and the strengthening of the EKWC towards summer, both of which are typical of this region, are the major factors governing the seasonal variation of the UWE.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.30 no.6
• /
• pp.1044-1055
• /
• 1997

To find out generating mechanism of eddies in the polar frontal zone of the East Sea, we carried out a series of numerical experiments using the nonlinear $1^{1/2}-layer$ model allowing the effect of the polar front. We assumed the polar front at about $39^{\circ}N$ in zonal direction with the cold water region in the northern part and the warm water region in the southern part of the model ocean. To examine the effect of the frontal motion without the influence of the Tsushima Current from the beginning of the geostrophic adjustment, the initial state of the model ocean was assumed motionless. Eastward current was caused by the geostrophic adjustment process in the polar frontal zone that induced a steady northward coastal current along the Korean coast to satisfy the mass continuity. The overshooting of this coastal current acted as an initial disturbance of the zonal flow field which caused meanders and eddies. The spatial scales of eddies were in good agreement with the baroclinic instability theory.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.26 no.6
• /
• pp.580-593
• /
• 1993

The Tsushima Current has been known to branch out from the Kuroshio west of Kyushu and to flow north to the Korea Strait. Then, it has to flow across the isobaths and so needs some driving forces. As the forces, sea level difference between the Korea and Tsugaru Straits, Reynolds stress west of Kyushu and density differences have been suggested, In this paper, their roles have been numerically studied in the barotropic case. Model results show that the Tsushima Current is possible without any above force. The flows just follow isobaths over the East China Sea. They seem to be driven by their own dynamics without any external force. The mechanism is just like outflows from a gap. Model results also show that the flows in this area could be significantly affected by the external forces such as Reynolds Stress. Then the dynamics and flows in real ocean might be complicated. However, the barotropic study tells us that the Tsuahima Currents is basically driven by geostrophic adjustment.

• Journal of the korean society of oceanography
• /
• v.37 no.1
• /
• pp.20-26
• /
• 2002

The offshore extension of the East Korean Warm Current (EKWC) mostly turns anti-cyclonically around the Ulleung Warm Eddy (UWE). This fact needs to be dynamically explained because a rectilinear stream past a circular cylinder is normally expected to have a flow pattern symmetric about the stream axis. For this purpose, a simple analytical model is presented in this paper. This model shows that the EKWC's tendency to be anti-cyclonic around the UWE is due to the anti cyclonic circulation generated around the UWE. This tendency results from the geostrophic adjustment between the UWE and the ambient EKWC water. As the strength of the UWE decreases, relative to the EKWC, this model shows that the flow pattern gradually changes from circular to rectilinear.

• 한국해양학회지
• /
• v.22 no.2
• /
• pp.63-70
• /
• 1987

Existing oceanographic data indicate that tidal mixing fronts generally prevail in the Eastern Yellow Sea along the Korean coast. In the Western part, these fronts seem to be much weaker. These fronts are believed to be generated mostly by spatially different tidal mixing. The geostrophic adjustment model applied to the observed density structure gives the mixed coastal water flowing northward and the offshore waters(both surface warm and bottom cold waters) flowing southward along the Korean coast. The transport of each water amounts to O(10$\^$4/)m$\^$3//sec.

• 한국해양학회지
• /
• v.24 no.1
• /
• pp.29-38
• /
• 1989

It has been believed that the circulation in the Japan Sea involves separation of current from the Korean coast and formation of a cold cyclonic gyre in the north. To explain this, a simple quasi-geostrophic linear model is considered. The model is basically of an inflow-outflow system. The local forcings, wind and air-sea heat exchange together with damping (both mechanical and thermal), are imposed upon. The results show that only the buoyancy damping due to perturbations from local thermal adjustment can cause the separation and the gyre. Various types of circulation patterns are possible depending on the intensity of the thermal forcing.