Eddy-induced flow of Scotian Shelf water across Northeast Channel, Gulf of Maine

Abstract

Historical and recent data show the episodic occurrence of cold, low salinity water, flowing southwestward along the outer shelf on southern Georges Bank during spring. Careful analysis indicates that the southwestern Scotian Shelf is the source of this water. For example, during April–June 1995, sea surface temperature (SST) images derived from infrared satellite data show intermittent, curvilinear tongues of cold Scotian Shelf water (SSW) crossing Northeast Channel from Browns Bank to eastern Georges Bank. During one particular event (23 April–1 May 1995), SST patterns were found to be consistent with cross-channel flow of SSW along the northern margin of a cyclonic eddy located within Northeast Channel. In addition, SST patterns during the period suggest that the cyclonic eddy is elliptical, with a greater along-channel dimension (∼50 km) relative to its cross-channel dimension (∼25 km). Furthermore, subsurface temperature, salinity and velocity from mooring NECE (42° 18′N, 65° 51′W) located in Northeast Channel show evidence for the passage of a cyclonic eddy through the mooring array during the same time period. The cyclonic eddy’s influence at NECE was noted throughout the entire water column. The strength and frequency of such eddies in Northeast Channel may play a large role in controlling the injection of mass, heat, salt, plankton and small fish onto Georges Bank during spring.