dense plume. A force of pressure gradient drives bottom dense plumes toward offshore, as the same as the experiments with no alongshore variation. The force also drives surface water, accompanied with the development of the bottom dense plumes. The surface water flows with an opposite direction of the bottom dense plume. In other word, the force makes a vertical circulation in the canyon and drives a left-bounded surface flow over the slope region. At the mouth of the canyon, the surface water flowing with a left-bounded direction is stretched and a cyclonic eddy is generated over the outflow of the bottom dense plume.
After the eddy generation at the mouth of the canyon, the cyclonic eddy interacts with the anticyclonic motion of the bottom dense plume. Figure 3 shows the salinity and velocity fields at day 24. The cyclonic eddy, which is marked 'A', moves with the bottom dense plume to the location around x= 177km and y=122km. A new cyclonic eddy, which is marked 'B' in Figure 3a is generated at the mouth of the canyon again. After that, a chain of eddies generates from the mouth of the canyon and travels with the bottom dense plume (Figure 3b). Water within the surface cyclonic eddies originates in the continental shelf and the shelf break regions, as shown in Figures 2a and 3a. It is suggested that the cyclonic eddies accompanied with the outflow of the bottom dense plume carry the shelf water to the basin side.
4. CONCLUDING REMARKS
The effects of changes in bottom topography to the transport process of shelf water were examined using numerical experiments. Changes in the depth and bottom slope control the transport process. Dense shelf water is transported by eddy flux in a continental shelf region and by bottom dense plume in a slope region. A salinity front is developed between the dense shelf water and the offshore surface water. The location of the front corresponds to not only the shelf break but also the location to stabilize the surface left-bounded current. The shelf break front show that dense shelf water is prevented from being transported farther offshore by eddy flux.
Submarine canyon is known as one of the generation area of eddies which has properties of shelf water. A numerical experiment was carried out to examine the effect of submarine canyon to the shelf water transport. Cyclonic eddies are generated over outflow of the bottom dense plume at the mouth of the canyon. The eddies interacts with the outflow of the bottom dense plume and moves offshore. Water in the cyclonic eddies originates in the shelf region. One possible mechanism of such cyclonic eddies is suggested by the results of the numerical simulation.
REFERENCES
Chapman, D.C.. and G. Gawarkiewicz, 1995, Offshore transport of dense shelf water in the presence of a submarine canyon, J. Geophys. Res.. 100, 13,373-13,387.
D'asaro E.A., 1988, Generation of Submesoscale Vortices: A New Mechanism, J. Geophys. Res., 93, 6685-6693
Gawarkiewicz, G., and D.C.Chapman, 1995: A numerical study of dense water formation and transport on a shallow, sloping continental shelf, J. Geophys. Res,. 100, 4489-4507.
Jiang, L., and R.W.Garwood Jr., 1995: A numerical study of three dimensional bottom plumes on a southern ocean continental slope, J. Geophys. Res., 100, 18,471-18,488.
