The Dynamic Structure of the Frontal Zone in the Coastal Upwelling Region off Oregon

Abstract

We studied the frontal zone of the coastal upwelling region off Oregon, from observations made in two successive years. The measurements were made between July and September in 1965 and 1966. The alongshore flow field was determined by combining direct measurements and geostrophic calculations. A near-surface southward jet and a subsurface northward undercurrent existed in the frontal zone. They were separated by an inclined frontal layer (permanent pycnocline). The frontal layer tended to intersect the sea surface about 10 km offshore, where a surface front was formed. Through a combination of direct current measurement and water mass analysis, the cross-stream flow was estimated to be seaward near the surface, shoreward at the top of the inclined frontal layer, but seaward at the bottom of the inclined frontal layer and shoreward below that. During a 25 h anchor station, a high degree of correlation existed between the vertical structure of the alongshore and cross-stream flows. An anomalously ... Abstract We studied the frontal zone of the coastal upwelling region off Oregon, from observations made in two successive years. The measurements were made between July and September in 1965 and 1966. The alongshore flow field was determined by combining direct measurements and geostrophic calculations. A near-surface southward jet and a subsurface northward undercurrent existed in the frontal zone. They were separated by an inclined frontal layer (permanent pycnocline). The frontal layer tended to intersect the sea surface about 10 km offshore, where a surface front was formed. Through a combination of direct current measurement and water mass analysis, the cross-stream flow was estimated to be seaward near the surface, shoreward at the top of the inclined frontal layer, but seaward at the bottom of the inclined frontal layer and shoreward below that. During a 25 h anchor station, a high degree of correlation existed between the vertical structure of the alongshore and cross-stream flows. An anomalously ...