Alongshore Coherence on the Pacific Northwest Continental Shelf (January–April, 1975)

Abstract

Abstract 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° intervals. Low-frequency (<0.6 cpd) fluctuations in alongshore current, alongshere 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 phases 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, rather than due to t...