CURRENT VARIABILITY AND UPWELLING ALONG THE NORTH SHORE OF BAIE-DES-CHALEURS

The circulation and temperature variability along the north shore of B aie des Chaleurs is investigated from the first extensive set of moore d current-meter data. Instruments were deployed from July to December of 1985, 1986 and 1987 at three locations. The moorings were placed wi thin an internal Rossby radius of deformation of the coast and the sit es had a total alongshore separation distance of 100 lan. The currents were primarily directed alongshore and the variability was dominated by the tides. The tidal amplitudes were 0.05-0.25 m s-1 in contrast to low-frequency (periods above 1 d) speeds that were typically <0.04 m s-1. The mean residual currents ranged from 0.01-0.1 m s-1 and are sho wn to dominate the advective displacement of passive particles for per iods above 5 d The mean circulation was westward in summer but reverse d in early autumn in the outer half of the bay. The westward flow is b elieved to be an extension of the Gaspe Current. A reduction in the st rength of the Gaspe Current, coupled with an increase in the eastward wind stress, is proposed as the cause of the flow reversal in autumn. Large-amplitude temperature fluctuations were observed at periods of 5 -10 d with high coherence between sites. The temperature oscillations were generated near the mouth of the bay by alongshore winds and propa gated westward along the north shore at the internal gravity wave spee d. These properties are consistent with those of an internal Kelvin wa ve, although modification by topographic influences is likely. Wind ty pically accounted for 40-65% of the observed temperature variance.