Abstract

Using Wright and Loder's (l985a,b) depth-dependent tidal rectification model and Garrett and Loder's (1981) diagnostic frontal circulation model, predictions of the residual circulation associated with the topographic rectification of tidal currents and the summertime density field on the northwestern and open ocean sides of Georges Bank are made and compared with observations. In general, the estimates of both wintertime and summertime along-isobath currents are in qualitative agreement with observations, but the agreement between predicted and observed cross-isobath currents is poor. The circulation associated with tidal rectification is primarily along isobaths in an anticyclonic sense around the Bank at all depths. The cross-isobath circulation is much weaker and, in the Eulerian specification, is dominated by two cells with opposing current directions. However, a significant Stokes velocity is predicted such that the along-isobath Lagrangian current is generally less than its Eulerian counterpart, and the cross-isobath Lagrangian current is sometimes in the opposite direction to its Eulerian counterpart. Both the along-isobath and cross-isobath currents associated with tidal rectification are predicted to be significantly stronger in summer than in winter due to a reduction in the strength of friction as a result of reduced wind stress and increased density stratification.An additional contribution to the anticyclonic circulation around Georges Bank is associated directly with the summertime tidal front around the Bank. This flow component is predicted to form a second intense along-isobath jet on the northwestern side, slightly off-bank of that due to tidal rectification, and a broader flow on the open ocean side. The associated cross-isobath circulation is predicted to be much weaker than the along-isobath circulation, with a general on-bank bottom flow on both sides of the Bank.

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