FY 1986

On the general circulation in the subarctic Pacific

Reed, R.K., and J.D. Schumacher

In Proceedings of the Workshop on the Fate and Impact of Marine Debris, NOAA Tech. Memo. NMFS-SWFC-54, R.S. Shomura and H.O. Yoshida (eds.), Honolulu, HI, 26–29 November 1984, 483–496 (1985)

This work attempts to summarize the major features of surface circulation in the subarctic Pacific (from lat. 40°N to the Bering Strait). Effects of the density distribution (geostrophic flow) and wind drift are considered. The Subarctic Current is a slow, eastward drift between lat. 40° and 50°N; in winter speeds increase about fourfold as a result of strong eastward winds. Speeds in the swifter Kamchatka Current-Oyashio may also be enhanced by winter winds. The Alaskan Stream flows westward along the Alaska Peninsula and Aleutian Islands at peak speeds in excess of 100 cm/s, but it does not seem to have any large seasonal variation. Coastal curents off Oregon-Washington generally reverse with a reversal in the seasonal winds. Off southeast Alaska, the northward coastal currents are enhanced by winter winds. The coastal Kenai Current on the west side of the Gulf of Alaska increases in speed from about 25 to 100 cm/s in the fall as a result of a maximum in freshwater discharge. The Kuroshio and Alaskan Stream undergo occasional large interannual variations; the processes in neither system are completely understood, however. El Niño events also produce dramatic changes in water properties (and perhaps currents) along the eastern margin of the North Pacific. The climatological map of near-surface flow can be used to provide estimates of the movement and transit time of material in the ocean. Off Oregon-Washington and southeast Alaska, winter storms commonly cause shoreward movement that is greater than the alongshore flow.