Variability of circulation induced by the separation of Gaspe Current in Baie des Chaleurs (Canada): observational studies

The observed variability of summer circulation in the Baie des Chaleurs (BdC, Canada) is found to be largely controlled by the intrusion/separation processes of a coastal jet Gaspe Current (GC) at the bay entrance. An analysis of hydrographic and current meter data showed that the mean counter-wind cyclonic circulation in the BdC from spring to the beginning of the cooling season in 1991 was ascribed to the westward intrusion of the GC. The forcing mechanism of the GC on the BdC was determined by the characteristics of the coastal jet separation. Under the intrusion regime, the GC entered into the BdC along the north coast of the bay, suppressed the local wind-driven eastward currents and formed a cyclonic circulation in the bay. Under the separation regime, GC mainly passed across the entrance of the BdC with the formation of an anticyclonic recirculation at the lee of the jet near the bay entrance and a weaker cyclonic circulation in the bay. Dynamics of the boundary current separation is utilized to reason the observed variability of flow field in the BdC.