|Abstract or Summary
- A time series of hourly surface current maps in the shelf waters off Newport, Oregon,
was made during April–September 2001 using five SeaSonde HF current mappers, during
Coastal Advances in Shelf Transport (COAST). The surface currents responded rapidly
to the changing winds, in repeated patterns that were strongly affected by bottom
topography. An equatorward current jet repeatedly formed in response to upwelling winds,
its strength, but not its trajectory, covarying with the meridional wind stress. Near Cape
Foulweather (44.8°N), where the shelf begins to widen, the jet rotates, weakens, and
trends offshore to the south first along, then across, the isobaths. Below Cape Foulweather,
inshore of the jet, a lee region of generally weak currents was commonly observed.
The equatorward jet core was most commonly observed near the 80-m isobath between
45.0°N and 44.4°N, but transited offshore between spring and summer over Heceta Bank.
At Newport (44.6°N), it was rarely observed less than 8 km from the coast. A second,
inshore, equatorward jet, previously unknown, was observed repeatedly south of Waldport
(44.4°N). Sustained downwelling wind episodes produced poleward currents, though
less responsively north of Cape Foulweather. Strongest poleward flow was generally
trapped near the coast. Surface currents were correlated with the northward wind, except
regionally far from shore over Heceta Bank, responding within half a day. Response to the
wind varies spatially, being intensified in the narrow shelf (northern) region. The
equatorward jet persists through periods of zero wind forcing. Coastal sea level covaries
with the meridional wind and the primary mode of ocean current response.