Alongshore coherence on the Pacific Northwest Continental shelf (January--April, 1975)
During the winter and spring of 1975, current observations were made simultaneously at five locations between Tofino, British Columbia, and Newport, Oregon, a distance of 480 km. Sea level and atmospheric pressure observations were available at three locations alongshore, and wind observations, at four locations. Computed (Bakun) winds were available at 3/sup 0/ intervals. Low-frequency (<0.6 cpd) fluctuations in alongshore current, alongshore wind, and subsurface pressure were significantly coherent over this distance. Forcing by the local wind dominated the response at each location: alongshore current and sea level fluctuations were significantly coherent with the local alongshore wind, and local phase relationships were consistent with phase predicted by the local model of Hickey and Hamilton (1980). The high alongshore coherence observed in the current and subsurface pressure fluctuations is shown to be a result of alongshore coherence in the forcing, i.e., in the wind field. Moreover, although alongshore phase differences were too small to be associated with freely propagating waves, at the frequencies where alongshore coherence of the current and sea level fluctuations was strongest, the alongshore phase differences were consistent with local wind forcing. Alongshore differences in fluctuations could be directly related to alongshore structure in the wind field, providing independent evidence for local wind forcing.
- Research Organization:
- Department of Oceanography, University of Washington, Seattle 98195
- OSTI ID:
- 6023798
- Journal Information:
- J. Phys. Oceanogr.; (United States), Vol. 11:6
- Country of Publication:
- United States
- Language:
- English
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