FY 1978

Circulation in the Strait of Juan de Fuca: Some recent oceanographic observations

Cannon, G.A. (ed.), J.R. Holbrook, and R.A. Feely (ed. assts.)

NOAA Tech. Report ERL 399-PMEL 29, NTIS: PB-293514, 49 pp (1978)

Oceanographic research in the Strait of Juan de Fuca and some of its adjacent waterways, emphasizing transport mechanisms that might affect the redistribution of spilled oil, has focused on near-surface circulation and its driving mechanisms. Moored current meters, surface drift cards, satellite images of suspended sediment, and an oil-spill trajectory model were used. The largest flow variations were found during fall-winter-spring. Drift cards tended to ground on Vancouver Island in winter, on the Olympic Peninsula in summer, and on beaches in the eastern basin of the Strait throughout the year. Trajectory model experiments also showed flow ending on beaches in the eastern basis. Numerous tidal fronts were observed north and south of the San Juan Islands, and near-shore eddies occurred everywhere on the down-current sides of headlands. Both of these phenomena tend to concentrate floating or suspended material. Moored current meters showed winter intrusions of oceanic surface water almost to Port Angeles lasting several days to over a week. Outflow often occurred only in the deeper water, with surface water being retained within the system. Winds appeared to be the major cause of all flow variations. Indications were that significant volumes of any contaminant would probably reach beaches within the estuary.