TERRAPUB Journal of Oceanography

Journal of Oceanography, Vol. 48 (No. 2), pp. 193-219, 1992

Effects of a Continental Slope along the Western Boundary on the Abyssal Circulation

Minoru Nakata1, Shigeaki Aoki2 and Nobuo Suginohara1

1Center for Climate System Research, University of Tokyo, Meguro-ku, Tokyo 153, Japan
2National Research Institute for Pollution and Resources, 16-3, Onogawa, Tsukuba-shi, Ibaraki 305, Japan

(Received 9 September 1991; in revised form 16 January 1992; accepted 29 January 1992)

Abstract: To investigate effects of a continental slope along the western boundary on the abyssal circulation, numerical experiments using multi-level models were carried out. An ocean which extends over the northern and southern hemispheres is forced by cooling inside the ocean at the southwest corner of the basin and uniform heating through the sea surface. When the reference density for the cooling is vertically uniform, effects of the slope emerge clearly for the slope with considerably broad width. The deep western boundary current flowing over the slope feeds no bottom flows in the southern hemisphere, and carries the warmed deep water into the northern hemisphere. This leads to the increased meridional density gradient, which results in the modification of deep flow patterns. When the reference density is vertically distributed, the upper and lower northward flowing western boundary currents form in the deep layer. As the density stratification relaxes the topographic control, the westward intensification of the upper boundary current is achieved over the slope. The intensified flow is accompanied by the countercurrent and they form the horizontal recirculation over the slope. However, the effects are confined around the slope region and the interior flow patterns do not change. The lower boundary current is not significantly affected by the slope and has the large width with no countercurrent. It is found that the actual continental slope does not have significant effects on the gross feature of the thermohaline circulation.

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