A fluorescent dye tracer, fluorescein, injected into the bottom mixed layer (BML) at the off-bank edge of the tidal front on Georges Bank in late May and early June 1999 has provided the first quantitative measurement of an on-bank diapycnal Lagrangian flow through the front. From the warming of the dye patch, 1.9 x 10(-6) and 7.6 X 10(-6 degrees)C/s on the south flank and northeast peak, respectively, as it passed through the frontal temperature gradient, we infer a mean on-bank flow of 1.6 cm/s on the south flank and 3.1 cm/s on the northeast peak. The heat flux required for this warming is predominantly due to vertical mixing within the tidal front. From the dispersion of the dye patch, we estimate a vertical diffusivity of 1.6 and 3.1 X 10(-3) m(2)/s and a cross-front diffusivity of 18 and 30 m(2)/s on the south flank and northeast peak, respectively.The evolution of a second dye injection on the south flank was distinctly different from the first because of the proximity of the foot of shelfbreak front now displaced onto the bank by a transient meander to within 6 kin of the tidal front. Although the dispersion of this patch was the same as for the first injection, its cross-bank displacement was much less reflecting the divergence of the cross-bank flow in this region. (C) 2002 Elsevier Science B.V. All rights reserved.
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