FY 1986

Interchanges between coastal and fjord circulation

Cannon, G.A., and D.E. Bretschneider

In Contaminant Fluxes Through the Coastal Zone, G. Kullenberg (ed.), Rapp. P.-v. Réun. Cons. Int. Explor. Mer, 186, 38–48 (1986)

Observations have demonstrated the role of non-local meteorological forcing in modifying circulation both in coastal plain estuaries and in fjords. In the Strait of Juan de Fuca, the southernmost glacially carved waterway in western North America, which enters the Pacific between Canada and the United States, reversals in flow are accompanied by large intrusions of surface coastal water lasting from a few days to more than a week. Storm-related southerly winds pile up water along the coast through Ekman transport, and this results in decreasing and then reversing the longitudinal sea surface slope in the estuary. As far inland as 90 km where the estuary is still greater than 100 m deep, observations have shown the normal estuarine flow pattern reversed. This is accompanied by a seaward retreating of the deeper saltier water and a landward intrusion of near-surface fresher and warmer water. The flux of water and salt through a section shows dramatic changes during these two flow regimes. Thus, the exchange of water, and hence contaminants, between the estuary and ocean can be expected to vary on a large scale in both space and time.