This study was funded by the EU MAST-2 program, DYNAMO CT930060. I thank George Nurser, Peter Killworth, and Keith Haines for helpful discussions, and Rainer Bleck and Linda Smith for providing the numerical code. I also thank the anonymous referees for helpful suggestions.
Bleck, R., and L. T. Smith, 1990: A wind-driven isopycnic coordinate model of the North and equatorial Atlantic Ocean. I. Model development and supporting experiments. J. Geophys. Res, 95 , 3273–3285.
Haines, K., 1991: A direct method for assimilating sea surface height data into ocean models with adjustments to the deep circulation. J. Phys. Oceanogr, 21 , 843–868.
Haines, K., P. Malanotte-Rizzoli, R. E. Young, and W. R. Holland, 1993: A comparison of two methods for the assimilation of altimeter data into a shallow-water model. Dyn. Atmos. Oceans, 17 , 89–133.
Rhines, P. B., and W. R. Young, 1983: How rapidly is a passive scalar mixed within closed streamlines? J. Fluid Mech, 133 , 133–145.