A Numerical Study on Density Current Descending Along Continental Slope
Kiyoshi Tanaka
Department of Geophysics, Graduate School of Science, Kyoto University,
Kyoto 606-8224, Japan
Tel: 81-75-753-3924
Fax: 81-75-753-3923
tanaka@kugi.kyoto-u.ac.jp
Kazunori Akitomo and Toshiyuki Awaji
Numerical experiments with a three-dimensional nonhydrostatic ocean model, having a continental shelf and slope, have been carried out to investigate the descending process of dense water, which is essential to deep and bottom water formation in polar oceans. Density current is driven by negative buoyancy flux supplied uniformly at the coastal end of the continental shelf. The sloping bottom has two effects operating oppositely on the descending process of dense water. One is to enhance the instability of flow to a rapid development of eddies. The other is to hinder a cross-slope movement of the eddies. The former effect can lead to the effective downslope transport of dense water if the eddies are detached to move offshore smoothly, while the latter prevents it. Therefore, on a gentle slope such as continental shelf, eddies develop slowly. Once fully developed, however, they move offshore smoothly to transport dense water effectively. On a steep slope such as continental slope, on the other hand, eddies do not readily move offshore though they develop more rapidly. As a result, the offshore transport of dense water becomes less effective.
