Lagrangian flow at the foot of a shelfbreak front
using a dye tracer injected into the bottom boundary layer

Robert W. Houghton

Lamont Doherty Earth Observatory
Palisades, NY 10964

(Submitted to GRL, March 1997)


Convergent flow at the foot of the shelfbreak front in the Middle Atlantic Bight has been detected using a dye tracer, Rhodamine-WT, injected into the bottom boundary layer. The observations substantiate model predictions by Chapman and Lentz (1994) of a small scale convergent flow in the vicinity of the front which would be very difficult if not impossible to detect in conventional moored current meter data. By following the dispersal of the dye patch over a 4 day period Lagrangian velocities of the order of 0.015 m/s with respect to the front were resolved even as the frontal boundary was displaced ~12 km onshore. The water following properties of the dye tracer provides a new technique for studying the small-scale circulation and mixing at the frontal boundary.

Designed by: D. Jarvis Belinne
Lamont-Doherty Earth Observatory of Columbia University