AbstractsGeography &GIS

Hydrographic and bathythermograph data taken off the Oregon coast during a two week period in August of 1969 were analyzed to determine if heat content and mixed layer depth may be used as indicators of Columbia River plume water. Heat content was found to be a poor indicator of plume water because of large additions of heat to the plume as the waters flowed southward and because the layer over which heat content was integrated (0 to 20 meters) was inconsistent with the depth of the plume. High variability among observations made analysis of mixed layer depth difficult and reduced its utility as an indicator of plume waters. Hydrographic sections taken during the summer months off Oregon from 1960 through 1969 were also examined. The axis of the Columbia River plume was located in 70 instances. The salinity axis was found to lie inshore of the temperature axis by a mean distance of 8.5 nautical miles. This displacement increased downstream and was most pronounced in July and August. A simple model showed the displacement to be the result of a large temperature gradient across the nearshore portion of the plume pynocline.