Towards Determining the Circulation of the North Atlantic and Caribbean Sea

Simulations of the North Atlantic Ocean circulation have been plentiful over the years, and although qualitatively similar, numerous significant discrepancies have arisen. In this study, a simple analytical model is developed, which expresses the transport in terms of a wind-stress integral and specified thermohaline-driven western boundary current. The model is especially powerful for determining the connection between the Ocean and Caribbean Sea, as it enables the wind-stress bands, which determine a particular strait transport to be readily identified. For example, Windward Passage, often regarded as a major inflow channel for the Caribbean Sea, is shown to lie in a dynamical regime where its transport can be readily reversed. Hence, occasional observations of almost no mean flow in the Passage are probably not erroneous, but likely provide important information on long-term changes in the Atlantic circulation and forcing. The robust major inflow passage is identified as Anegada Passage, as suggested by some tracer studies, but which has received little attention to-date. Realistic transports through the Windward Island passages are only obtained if the frictional resistance in these passages is an order of magnitude larger than used in the western passages. It is noteworthy that this is not inconsistent with the passage of westward-propagating Rossby waves from the Atlantic into the Caribbean observed in TOPEX data by several authors. Water masses from the South Atlantic are partially deflected northward along the outer arc of the Windward Islands, and enter the Caribbean Sea through Anegada Passage. The model suggests that for realistic friction parameters, South Atlantic water masses are unlikely to be found in the more western passages, or in the western boundary current skirting the edge of the Bahama Banks.