HR: 1340h
AN: OS13A-0509    [Abstracts]
TI: Frontal circulation and sediment distribution in the Columbia River plume during the 2004 RISE cruise
AU: * Horner-Devine, A R
EM: arhorner@alumni.princeton.edu
AF: Harris Hydraulics Lab, Department of Civil and Environmental Engineering, University of Washington, Box 352700, Seattle, WA 98195-2700 United States
AU: Chisholm, T A
EM: 503-748-1372
AF: OGI/OHSU, Department of Environmental and Biomolecular Systems, OGI School of Science and Engineering, Oregon Health and Science University, 20000 NW Walker Rd, Beaverton, OR 97006-8921 United States
AU: Jay, D A
EM: djay@ebs.ogi.edu
AF: OGI/OHSU, Department of Environmental and Biomolecular Systems, OGI School of Science and Engineering, Oregon Health and Science University, 20000 NW Walker Rd, Beaverton, OR 97006-8921 United States
AB: The National Science Foundation-funded RISE (River-Influenced Shelf Ecosystems) project seeks to understand how the Columbia River plume affects the productivity of the Washington and Oregon shelves by redistributing and mixing nutrients in coastal waters. Based on observations from the first RISE cruise, we present a description of the frontal circulation and sediment distribution in the Columbia River plume. River-borne sediments may play an important role in mediating productivity in this system by transporting nutrients and regulating light availability in the water column. During the first RISE cruise on July 8-28, 2004, we sampled the upper water column of the plume area intensively with a Triaxus tow-fish aboard the R/V Pt Sur. The Triaxis was outfitted with three CTDs, a fluorometer, a transmissometer, a nitrate sensor, a Laser In-Situ Scattering Transmissometer (LISST-25), an upward looking acoustic Doppler current profiler (1200 kHz), and a laser-optical plankton counter (LOPC). We obtained additional information on the sediment class distribution in the plume with a LISST-100 mounted to a CTD array and deployed separately from the Triaxis. Preliminary results suggest that strong fronts are generated on the windward side of the plume and that fronts on the northern side of the plume are typically stronger than those on the south. These fronts create strongly convergent flow near the surface and penetrate well below the buoyant surface layer. In shallow areas the front-induced flow appears to re-suspend nutrient-rich bottom sediments.
DE: 4219 Continental shelf processes
DE: 4528 Fronts and jets
DE: 4558 Sediment transport
SC: Ocean Sciences [OS]
MN: 2004 AGU Fall Meeting