Description of wind, current, and bottom pressure variations on the continental shelf in the northeast Gulf of Alaska from February to May 1975

Abstract

A moored array with current and bottom pressure measurements on the continental shelf in the northeast Gulf of Alaska was used to study the interrelationships among the low-frequency (<0.025 cph) variations of wind, current, and bottom pressure for the period February–May 1975. The circulation can be divided into a winter and a spring regime. This seasonal change was most clearly seen in the bottom pressure and its correlation with the alongshore wind and current. During February the wind, bottom pressure, and currents were mutually coherent. A simple linear correlation between bottom pressure and alongshore current accounted for much of the variance. However, during March and April the coherences were low, and the linear correlation was no longer valid. The data suggest that offshelf processes or nonlocal effects became more important. The monthly averaged data also indicated a seasonal change. The mean bottom pressure dropped by 12 cm from February to April. This was accompanied by only a 2-cm/s change in the mean alongshore flow. It was not possible with the available hydrographic data to determine the influence of deepwater baroclinic changes on the seasonal bottom pressure change.