Field off Oregon Based on Drift Bottle Data

Abstract approved: The fall-winter surface current field off Oregon was determined by analysis of ten years of drift bottle data. Computer programs were developed for generating bottle tracks on a numerical grid, for inter-polating bottle velocity components to fill void grid points and for smoothing irregularities in the velocity fields. Charts are presented showing the spatial distribution of surface currents determined in the study area of 5 ° latitude by 2-1/2 ° longitude. The mean currents for the fall-winter season have a predomi-nantly northerly flow with speeds increasing from the south to the north (from 0. 01 to 0. 35 knots). This probably is a consequence of the increase in speed of southerly winds from south to north in the study area during the fall-winter season. The northly flow in October during the years 1961-70, when compared with the dominant southerly flow during this month from measurements prior to 1935, may indicate Redacted for Privacy a major change of Davidson-California Current System within the past forty years. Apparent onshore flow may be introduced by bottle diffusion; this flow is prominant at all latitudes along which bottle releases are concentrated. An offshore flow component north of 0..46 30 N may be related to the Columbia River discharge and the westward extension of land