HR: 14:00h
AN: OS52H-01    [PDF]
TI: Mixing and Circulation at the New England Shelfbreak during NESPEX from Dye Tracer Studies
AU: * Houghton, R W
EM: houghton@ldeo,columbia.edu
AF: Lamont Doherty Earth Obs. of Columbia Univ., 61 Route 9W, Palisades, NY 10964 United States
AB: The three dye tracer releases during the New England Shelfbreak Productivity Experiment (NESPEX) were a continuation of a series of tracer experiments to investigate the mixing and circulation at the shelfbreak front. In the earlier three experiments (1996-1997) the convergence and detachment of the bottom boundary flow was detected. Here the mixing is diapycnal with dye patch T/S properties evolving along the shelf-slope water mixing line. The NESPEX dye releases were also at the shelfbreak front but higher in the water column. In the interior of the `cold pool', inshore of the front, there was a weak ($<=$0.5 cm/s) offshore isopycnal flow along essentially horizontal density surfaces. Along the shelfbreak front above the bottom boundary layer there was direct evidence of isopycnal upwelling flow. Much of this exchange is characterized by filaments of water $\sim$1 km in scale moving offshore with speeds up to 8 cm/s apparently generated by a highly sheared flow field. Horizontal diffusivities are approximately 10 m2/s in the bottom mixed layer and 3-5 m2/s in the stratified front. Vertical diffusivities are approximately 3x10-5 m2/s in the cold pool and 1.3x10-5 m2/s in the shelfbreak front above the bottom boundary layer.
DE: 4219 Continental shelf processes
DE: 4279 Upwelling and convergences
DE: 4528 Fronts and jets
DE: 4568 Turbulence, diffusion, and mixing processes
SC: Ocean Sciences [OS]
MN: 2004 Ocean Sciences Meeting