Recent Observations of Variability in the Path and Vertical Structure of the Alaskan Stream

Abstract

Current records were recently obtained from two sites on the Continental slope southwest of Kodiak Island. At the inshore site (10-month record), flow mainly resembled the weak shelf-break flow typical of the Gulf of Alaska. Except for two periods, each of ?3 months duration, the offshore site (31-mouth record) was in the path of the Alaskan Stream. During the Alaskan Stream segments, flow Characteristics (low eddy energy, high vertical coherence, and high stability) were similar to those in the stream at other locations. When the stream was absent from the offshore site, it made a seaward excursion of ?50 km as evidences by satellite-tracked drifters. The cause of this migration is unclear. During a period of ?6 months, a subsurface velocity maximum was measured at 165 m. Flow near 1000 m was very weak for almost two years; geostrophic flow estimates, however, suggest this is a rare situation.