THE RESPONSE OF AN OPEN STRATIFIED BAY TO WIND FORCING

Current and temperature measurements collected during the summers of 1 974, 1975 and 1979 are used to investigate the wind-induced response o f St Georges Bay, Nova Scotia. A multivariate-frequency response analy sis shows that temperature and the along-bay component of current in t he lower layer are coherent with the local wind stress at periods of 2 -6 d, with the wind stress accounting for 35-65% of the observed varia nces. Winds are also coherent with the surface currents but account fo r only 20-25% of the variance. Two dynamically different regions are i dentified. Near the entrance to the bay, cross-bay wind stresses (tau( x)) produce Ekman drift with compensating flow in the lower layer. In the interior of the bay, the near-bottom currents are coherent with al ong-bay (tau(y)) wind stresses and are directed upwind. These currents are topographically steered and a response to surface pressure gradie nts set up by the wind. The surface gradients are believed to be part of the wind-induced set-up within the southern Gulf of St Lawrence.