Interannual variability (19481994) of the CIL core temperature in the Gulf of St. Lawrence

Abstract

The interannual variability (1948-1994) of the cold intermediate layer (CIL), defined here as the layer with T < 3°C, was investigated for six subregions of the Gulf of St. Lawrence. We first calculated a mean annual cycle of CIL properties for the six subregions (the Estuary, the Northwest, Northeast, Central, and Southern Gulf, and Cabot Strait). The midsummer warming rates thus obtained were then used to construct time series of the CIL core temperature extrapolated to July 15, using all available data from May 1 to September 30 of each year. Our most important result is that the mid-summer CIL core temperature was below normal from 1986 to 1994, this cold period being most intense from 1990 to 1994. We correlated the time series of CIL core temperature with average winter air temperatures from several weather stations inside and outside the Gulf to try to distinguish between local and remote atmospheric forcing and obtained the highest correlations with weather stations from the west coast of Newfoundland.