A SIMPLE-MODEL OF ABYSSAL CIRCULATION IN A CIRCUMPOLAR OCEAN

A simple barotropic model of abyssal circulation in a circumpolar ocea n basin is constructed. In the presence of a sufficiently high ridge, the classical Stommel and Arons theory applies here with very substant ial modifications. In the case with a point source at one side of the channel and a point sink at the other side of the channel, there is a through-channel recirculation in addition to the flow from the source to the sink. The volume flux of this recirculation is critically deter mined by the supercriticality of the ridge height. In the case with a uniform sink and point sources and sinks, the circulation is essential ly in the Stommel and Arons sense with one major novelty; that is, a t hrough-channel recirculating flow is generated. Both its strength and direction depend critically upon the model parameters. This suggests t hat the Antarctic Bottom Water formation could drive a substantial amo unt of westward flow that counterbalances the wind-driven eastward flo w. Last, a schematic picture of the abyssal circulation in an idealize d Southern Ocean is obtained. The most significant feature is the narr ow current along the northern boundary of the circumpolar basin, which feeds the deep western boundary currents of the Indian Ocean and Paci fic Ocean and connects all the oceanic basins in the Southern Ocean.