Annual Changes in the Oceanic-Coastal Waters of the Eastern Subarctic Pacific

The temporal variations of water characteristics and currents are reviewed both for the oceanic region of the eastern Subarctic Pacific and for the bordering coastal and fjord regions.In the oceanic region, an estuarine structure prevails, namely, an upper zone, halocline, and lower zone. The horizontal distributions of temperature of the upper zone (seasonal) for the years 1955 to 1966, and lower zone waters for the same years, excepting 1963 and 1964, off the British Columbia coast are presented. The extent of warm upper-zone waters was greatest in 1958 and 1963 and least in 1956 and 1965. Warm lower-zone waters extended furthest in 1958, 1961, and 1962, but did not retreat to the position observed in 1956. The mechanisms relating these waters to the bottom waters of the continental shelf are discussed.In the coastal and the inshore waters there is a pronounced annual cycle in the upper zone, generally with a temperature maximum and a salinity maximum in the summer. The deep water of the fjords opening directly on the Pacific is, in some cases, exchanged annually in the summer, when higher density subsurface water moves onto the continental shelf. In the fjords with indirect connection to the ocean, the deep water is exchanged irregularly at intervals of several years.