Modeling and Observational Studies of the Juan de Fuca Eddy

Michael Foreman¹, Barbara Hickey², Emanuele Di Lorenzo³, Amy MacFadyen², John Morrison¹, and Vera Trainer⁴

1 Institute of Ocean Sciences, Sidney B.C., V8L 4B2, Canada. E-mail: foremanm@dfo-mpo.gc.ca
2 School of Oceanography, University of Washington, Seattle, 98195-07940, USA
3 Scripps Institution of Oceanography, La Jolla, 92093-0224, USA
4 Northwest Marine Fisheries Service, NOAA, Seattle, 98122-2013, USA

Recent studies suggest that the Juan de Fuca Eddy, a seasonal nutrient-rich retentive feature off the Washington and British Columbia coasts, may be an initiation site for the toxigenic phytoplankton Pseudo-nitzschia (PN) that impact shellfish along the Washington coast. As part of ECOHAB PNW, a project funded by the Ecology and Oceanography of Harmful Algal Blooms program, the Regional Ocean Modeling System (ROMS) has been chosen to simulate CTD, ship-board ADCP, and mooring observations collected during a three-week cruise in June 2003. During this cruise, two periods of upwelling winds which supported the eddy were separated by a downwelling storm which caused the eddy to collapse. In this talk, we will show that model simulations not only reproduce this behavior, but also capture other major regional current features such as estuarine flow in Juan de Fuca Strait, the Vancouver Island Coastal Current, the Shelf Break Current, and the California Undercurrent.