Concurrent remote and in situ wave and current observations at a tidal inlet

Strong tidal currents can have a dominant influence on the incident wave field at tidal inlets such as Yaquina Bay in Oregon. Swift ebb currents, horizontal shear in the ebb jet, as well as complex bathymetry can affect the location, direction and severity of wave breaking along navigation routes. In combination with rapidly changing wave conditions, this wave breaking hazard can prove fatal for vessels entering or leaving harbors. However, efforts to model where these waves break remain challenging. This work gathers a comprehensive and concurrent set of field observations to capture wave and current conditions for future wave-current interaction model validation. The observations include remote and in situ measurements of the tidal currents and incident wave fields, as well as currents and waves directly offshore of the jetty entrance. Inter-jetty surface current measurements were gathered through the novel use of the RiverSonde (CODAR Ocean Sensors) UHF radar system. In addition, observations of the vertical structure of the currents were gathered with a nearby AWAC (Nortek) and ADCP. Directional wave spectra were collected by a WaveRider buoy that we deployed 5 km offshore along the 50 m isobaths. Finally, the Newport site is also the home of a long-term marine radar wave observing system, which is a node on the NANOOS observing system. Remote sensing observations of the breaking wave field from this system will be coupled with the in-situ observations and RiverSonde data in order to present a synoptic picture of wave-current interaction processes at this inlet. The overall goal of this work is to develop and validate a wave modeling system for this site that includes the effects of wave-current interaction. We are using the Unstructured-grid Simulating Waves Nearshore (UnSWAN) wave model covering the Newport coastal region. In addition, our collaborators are applying the Finite Volume Coastal Ocean Model (FVCOM) to Yaquina Bay and vicinity. We seek to combine and validate these two model systems. The presented work focuses on: 1) comparisons between the remotely - sensed surface currents in the channel with the co-located current profile data and 2) the influence of tidal currents at the bay mouth on the breaking conditions observed with the marine radar and comparisons of these observations to the UnSWAN predictions.