Meteorologically and Buoyancy Induced Subtidal Salinity and Velocity Variations in the St. Lawrence Estuary

Abstract

Meteorologically and buoyancy induced subtidal salinity and velocity variations in the St. Lawrence Estuary are reviewed using 1979 and 1982 current meter data and results of 2-D numerical models. The meteorological forcing shows oscillations with periods of 10–15 and 40–50 days, and a long-term trend with a time scale of approximately 130 days. The salinity data indicates that the 10–15 day forcing induced an interfacial oscillation which propagated anticlockwise in the lower estuary as a free internal Kelvin wave. However, the velocity data provide a different picture of wave propagation. The 40–50 day forcing induces an oscillation that occurs initially near the transition region between the Upper and Lower estuaries, and then propagates toward upstream and downstream regions. The oscillation also propagates toward the surface in the lower estuary. The long-period salinity variation in the Upper estuary observed in 1982 is induced mainly by wind-forcing.