(Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2001-09)
Katrein, Jody M.
As part of Phase III of the U.S. GLOBEC Georges Bank program, drogued
drifters and dye tracer were released into the pycnocline on the southern flank of
Georges Bank to measure advective and diffusive transport relative to the tidal
mixing front in May 1999. Potential density measurements placed the tidal
mixing front around the 50-55 m isobath on the southern flank. Drogued drifter
movement relative to the front was on the order of the drifter's slip velocity and
therefore did not support the existence of a mean, advective flow. No movement
relative to the front of the dye patch center of mass also indicated a lack of
advective flow. Diffusive transport did occur as the dye patch spread laterally
both toward and away from the front much as would be predicted by the diffusion
relationship of Okubo (1971), who summarized diffusion experiments in the
surface ocean. The dye did not spread symmetrically, but was rather elongated
along the isobaths. This can be attributed to vertical shear in the along-isobath
current that was measured by the shipboard ADCP.
