Flow variability at the tip of the Antarctic Peninsula

Recently ventilated water leaves the landlocked northwestern Weddell Sea near the Antarctic Peninsula and possibly spreads out into the basins of the world oceans at shallow to intermediate depths. To determine the pathways of the water through the complex topography and the flow variability, water-mass circulation and properties are described in the northwestern Weddell Sea and along the boundary of the Powell Basin by means of data from current-meter moorings and hydrographic sections. The mean flow is strongly controlled by the topography. Meso-scale, seasonal and interannual fluctuations are superimposed. The mean northward volume transport of shelf water, which represents the potential source water for intermediate layer ventilation, is estimated for the time interval between May 1996 and March 1998 to be 2.4±1.0 Sv. Water-mass properties suggest that much of this water leaves the Weddell Sea to Bransfield Strait and therefore does not reach the Weddell Scotia Confluence. The water masses are able to serve as the only source of Bransfield Strait deep water since the shelf water properties in the northwestern Weddell Sea vary over time within a range that corresponds to the required source waters. The Scotia Sea is supplied by water from the Powell Basin, which has varied significantly over the past two decades.