On the Role of Closed and Open Boundaries in a Model of the Tropical Atlantic Ocean

Abstract

A series of model experiments Of the tropical Atlantic Ocean is Performed to demonstrate the effect of various closed and open boundary configurations on spinup and steady state time sclaes. In response to forcing by idealized winds and a realistic seasonal cycle, the large-scale interior solutions are relatively insensitive to the choice of boundary condition. However, the choice of boundary condition does have an important impact on the structure and variability of the western boundary circulation, and its relation to the interior flow field. As expected, transient effects during spinup produced significant differences in western boundary coastal upwelling and downwelling regimes based on the implementation of closed or open boundaries. More importantly, the mere existence of certain western boundary features such as coastally trapped jet was strongly dependent on the choice of boundaries under mean and seasonal equilibrium conditions. In particular only those solutions with an open western boundary were able to simulate the continuous northwestward coastal flow of the North Brazil Current during spring and the complete eastward veering of this current into the North Equatorial Countercurrent during the fall.