Comparison of sea level and currents off the Oregon coast using mean monthly data

Graduation date: 1977Sea level and current data collected near Newport, Oregon are\ud compared to determine an empirical relationship from which the low\ud frequency (f < .1 cpd) alongshore current field over the continental\ud shelf is estimated from observed sea level measurements at the coast.\ud Regression analysis of the near-surface (20-25 m) currents\ud with sea level indicates the surface currents are in geostrophic\ud balance with the sea surface slope. Analysis of the alongshore shear\ud between the near-surface and deep (75-80 m) layers with sea level\ud shows the thermal wind relationship holds.\ud A near-surface regression model is developed from which the mean\ud monthly alongshore current 20-25 m below the surface can be estimated\ud with a standard estimate of error (σ[subscript ER]) less than six cm/sec.\ud The annual range at this depth is nearly 60 cm/sec. A regression\ud model for the alongshore shear is formed from which the mean vertical\ud shear is estimated with a σ[subscript ER] of .07-.10 cm/sec/m. The annual\ud range is approximately .8 cm/sec/m.\ud The surface currents are found to be predominantly driven by the\ud local meteorological conditions. Deep and near-bottom current observations\ud suggest the deep layer currents are primarily influenced by the\ud thermal wind relationship and the location of the California Undercurrent