Robert Houghton
Lamont Doherty Earth Observatory

Two cruises were undertaken in May and June 1999 in which dye patches were released to study cross-frontal exchange. On Oceanus Cruise 342, led by Bob Houghton of LDEO, dye was released in the bottom mixed layer. Jim Ledwell and Jim Churchill of WHOI led Endeavor Cruise 323/324 in which dye and drifters were deployed in the pycnocline and in the surface layer. Sampling on this cruise was done by the WHOI VPR group, yielding plankton distributions. Real time modeling was done on board by Dennis McGillicuddy.

Figure 1 shows the location of dye and drifter deployments during these cruises. The LDEO dye was Fluorescein injected into the bottom mixed layer on the stratified side of the tidal front. The WHOI dye was Rhodamine-WT: #1 injected into the surface (1-3 m ) layer and #2-4 into the pycnocline. During the WHOI dye injections additional WHOI drifters drogued at various depths were deployed in the dye patch. Drifters also drogued at various depths were deployed by Manning in April and May on NOAA cruises. See the time line for the temporal distribution of the experiments. The work is described in more detail in the following cruise reports:

Houghton, R. W., R/V Endeavor Cruise 342 to Georges Bank, Cruise Report, U. S. GLOBEC Northwest Atlantic/Georges Bank Program, 1999.

Ledwell, J. R., T. G. Donoghue, C. J. Sellers, J. H. Churchill, D. Torres, D. McGillicuddy, V. Kosnyrev, C. S. Davis, S. M. Gallager, C. J. Ashjian, A. P. Girard, P. Alatalo, and Q. Hu, Lagrangian Studies of the Tidal Mixing Front on Georges Bank, R/V Endeavor Cruises 323 and 324, Cruise Report, U. S. GLOBEC Northwest Atlantic/Georges Bank Program, 2000.

McGillicuddy, D. J., and V. K. Kosnyrev, Real-Time Modeling on Cruises EN323 and EN324, Cruise Report, U. S. GLOBEC Northwest Atlantic/Georges Bank Program, 1999.