HR: 10:35h
AN: OS12A-02    [Abstracts]
TI: Dye Tracer Experiments in the Hudson River Plume During LaTTE\#1, May 2004
AU: * Houghton, R W
EM: houghton@ldeo.columbia.edu
AF: Lamont Doherty Earth Observatory of Columbia University, 61 Route 9W, Palisades, NY 10964 United States
AU: Chant, R J
EM: chant@imcs.rutgers.edu
AF: Institute of Marine and coastal Sciences of Rutgers University, Dudley Road, New Brunswick, NJ 08903 United States
AB: During LaTTE \#1 (LAgrangian Transport and Transformation Experiment), in May 2004, a tracer experiment using Rhodamine dye was conducted to study the circulation and mixing in the Hudson River plume. The experiment consisted of two (28 kg) injections of Rhodamine-WT into the surface mixed layer of the plume. The dispersing dye patch was monitored in situ with a Chelsea Ltd. Aquatraka III fluorometer attached to an undulating Eco-shuttle for 1.2 and 2.2 days after the first and second injections respectively. Persistent upwelling winds prior to and during the first experiment drove the plume to the east along Long Island's South Shore. When winds shifted to downwelling a new plume quickly set-up along the New Jersey coast and propagated down shelf at speeds exceeding 50 cm/s. The second injection occurred in the leading edge of the new plume. Several aspects of the dye's behavior appear to be inconsistent with the expected Ekman response to downwelling winds. In particular, after injection the plume remained thin, dye penetrated into the halocline, and the salinity of the leading edge of the dye-patch increased rapidly. In contrast, Ekman theory would have predicted a landward movement of the dye and a thickening of the plume. Furthermore, the rapid salting of the plume during downwelling-favorable wind conditions differs from numerical results of Fong and Geyer. We speculate that time-dependency may play be an important factor in the early evolution of the plume's structure, circulation and mixing.
DE: 4219 Continental shelf processes
DE: 4568 Turbulence, diffusion, and mixing processes
SC: Ocean Sciences [OS]
MN: 2004 AGU Fall Meeting