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Article
The Columbia River Plume Study: Subtidal Variability in the Velocity and Salinity Fields
Geophysical Research Letters
  • B. M. Hickey, University of Washington - Seattle Campus
  • Leonard J. Pietrafesa, North Carolina State University at Raleigh
  • David A. Jay, Portland State University
  • William C. Boicourt, University of Maryland - Baltimore
Document Type
Article
Publication Date
5-1-1998
Subjects
  • Columbia River
Abstract
A comprehensive study of the strongly wind driven midlatitude buoyant plume from the Columbia River, located on the U.S. west coast, demonstrates that the plume has two basic structures during the fall/winter season, namely, a thin (~5~15 m), strongly stratified plume tending west to northwestward during periods of southward or light northward wind stress and a thicker (~10~40 m), weakly stratified plume tending northward and hugging the coast during periods of stronger northward stress. The plume and its velocity field respond nearly instantaneously to changes in wind speed or direction, and the wind fluctuations have timescales of 2-10 days. Frictional wind-driven currents cause the primarily unidirectional flow down the plume axis to veer to the right or left of the axis for northward or southward winds, respectively. Farther downstream, currents turn to parallel rather than cross salinity contours, consistent with a geostrophic balance. In particular, during periods when the plume is separated from the coast, currents tend to flow around the mound of fresher water. At distances exceeding about 20 km from the river mouth, the along-shelf depth-averaged flow over the inner to midshelf is linear, and depth-averaged acceleration is governed to lowest order by the difference between surface and bottom stress alone. In this region, along-shelf geostrophic buoyancy-driven currents at ~5 m (calculated from surface density) and along-shelf geostrophic wind-driven currents (computed from a depth-averaged linear model) are comparable in magnitude (~10-25 cm-1 ).
Description

Copyright 1998 American Geophysical Union.

The following article can be found online at: http://dx.doi.org/10.1029/97JC03290

* At the time of publication David A. Jay was affiliated with the Oregon Graduate Institute.

DOI
10.1029/97JC03290
Persistent Identifier
http://archives.pdx.edu/ds/psu/8029
Citation Information
Hickey, B. M., L. J. Pietrafesa, D. A. Jay, and W. C. Boicourt (1998), The Columbia River Plume Study: Subtidal variability in the velocity and salinity fields, J. Geophys. Res., 103(C5), 10,339--10, 368.