FY 1980

Some observations of physical oceanographic conditions on the northeast Gulf of Alaska continental shelf

Muench, R.D., and J.D. Schumacher

NOAA Tech. Memo. ERL PMEL-17, NTIS: PB81-102584, 84 pp (1979)

Circulation and hydrographic conditions on the northeast Gulf of Alaska continental shelf between Yakutat and Prince William Sound, Alaska, were investigated using current, temperature and salinity observations obtained in 1974–77. Flow on the shelf was westerly, with mean currents highest at the shelf break and decreasing toward the coastline. Mean current speeds near the shelf break were about 15 cm s in winter and decreased to about 5 cm s during summer. These seasonal variations were due primarily to variations in intensity of the wind-stress-driven Gulf of Alaska subarctic gyre. Prominent fluctuations in flow were superposed upon the westerly mean flow, and were at times sufficiently large to lead to reversals to easterly flow. These fluctuations were larger relative to mean flow during summer than in winter; the stronger mean flow in winter was sufficient to maintain westward flow at all times despite the larger fluctuations. Fluctuations in flow were apparently driven primarily by local wind forcing, though propagation of mesoscale eddies from the central Gulf of Alaska onto the shelf was probably a contributing factor.