Record Details
Interactions of wind-driven and tidally-driven circulation in the Oregon coastal ocean
ScholarsArchive at Oregon State University
| Field | Value |
|---|---|
| Title | Interactions of wind-driven and tidally-driven circulation in the Oregon coastal ocean |
| Names |
Osborne, John J. (John Joseph)
(creator) Kurapov, Alexander L. (advisor) |
| Date Issued | 2014-03-12 (iso8601) |
| Note | Graduation date: 2014 |
| Abstract | Influences of tidal and slower (subtidal) oceanic flows over the continental shelf and slope off Oregon are studied using a high-resolution ocean circulation model and comparative model-data analyses. The model is based on the Regional Ocean Modeling System (ROMS), a fully nonlinear, three-dimensional model (using hydrostatic and Boussinesq approximations). The model horizontal resolution is 1 km. The study period is summer 2002. Variability in the semi-diurnal internal (three-dimensional, baroclinic) tidal flows is influenced by the background conditions associated with coastal wind-driven summer currents. Our analyses reveal areas of intensified semidiurnal tide on the Oregon slope and the shelf and how these vary with change in the background conditions. Hot spots of barotopic-to-baroclinic energy conversion found on the slope occupy 1% of the slope area produce about 20% of the internal tide energy. At these locations, generation is well balanced by radiation of the internal tide energy away from the generation location. Intensity of the diurnal K1 and O1 tidal currents on the Oregon shelf is also influenced by the background stratification and alongshore currents associated with summer upwelling. Tidal currents are stronger in stratified conditions (as compared to an unstratified case). Intensity of the diurnal surface current is influenced by the advection of the alongshore wind-driven coastal current by cross-shore tidal current and also diurnal wind forcing. Analyses in this part are corroborated by comparisons with the high-frequency (HF) radar surface currents. Diurnal flows may dominate variability around Cape Blanco, a prominent geographical feature on the Oregon coast, where the surface diurnal currents may be in excess of 0.3 m/s. Analyses of the slope flows using a passive tracer released continuously at the bottom at the 300 m depth show the presence of the continuous undercurrent between Cape Blanco and Heceta Bank. In this area, the Reynolds-averaged term 〈v'q'〉 is computed, where v' and q' are the high-pass filtered (tidal) velocity across the 200-m isobath and the tracer concentration, respectively, and 〈∙〉 denotes the 40-hour half-amplitude low-pass filter. The Reynolds term contributes appreciably to the on-shelf tracer transport on subtidal scales. |
| Genre | Thesis/Dissertation |
| Topic | Oregon coastal ocean |
| Identifier | http://hdl.handle.net/1957/47884 |
