FY 1991

Observations of seasonal and interseasonal variability in Shelikof Strait, Alaska

Roach, A.T., and J.D. Schumacher

In Coastal Zone '91, Proceedings of 7th Symposium on Coastal and Ocean Management, ASCE, Long Beach, CA, 8–12 July 1991, 3304–3317 (1991)

Nearly five years of monthly mean current data from two locations (one nearshore on the shallow shelf and one in the Shelikof sea valley) are used in conjunction with surface geostrophic winds and indices of freshwater discharge and sea-level atmospheric pressure to quantify the relative importance of these forcing terms on the ocean currents. The Alaska Coastal Current, a baroclinic jet formed upstream of Shelikof Strait, has a strong baroclinic signal with a maximum in the fall due to the seasonal freshwater cycle. This current is the primary influence on the nearshore currents. The Aleutian Low pressure system, an index of cyclones propagating into the Gulf of Alaska, dominates the meteorological field in the winter and causes a strengthening of currents in the sea valley. The currents in the sea valley are in approximate geostrophic balance. NEPPI FOCI, an index of the strength and persistence of the Aleutian Low, is a good index both of current fluctuations in the sea valley and of year-to-year variability of the mean currents.