TEMPERATURE AND SALINITY VARIABILITY ON THE SCOTIAN SHELF AND IN THE GULF OF MAINE 1945-1990

Examination of temperature and salinity data from the Scotian Shelf, G ulf of Maine, Gulf of St. Lawrence, and the adjacent continental slope has shown that the dominant low-frequency event over the last 45 year s was a cooling and subsurface freshening of the water masses from 195 2 to 1967, followed by a rapid reversal of these trends. The largest t emperature and salinity changes (1952-1967) were 4.6-degrees-C and 0.7 , respectively, and occurred at about 100 m over the slope. Exchanges with shelf waters and vertical mixing gave rise to the surface manifes tation of this variability. The westward transport of the Labrador Cur rent was found to have similar variability, increasing from about 1 X 10(6) m3 s-1 in the early 1950s to about 4 x 10(6) m3 s-1 in the mid-1 960s. A simple model that accounts for this variation of transport and has a constant entrainment of North Atlantic water indicates that cha nges of the westward flow of the Labrador Current could contribute sig nificantly to the T-S fluctuations.