Effect of wind and local density on the subtidal circulation of the inner Scotian Shelf

Abstract

A comprehensive oceanographic data set was collected over the inner Scotian Shelf in February 1996. Hydrographic observations reveal that the water properties had typical wintertime distributions characterized by a two-layer system: relatively cold and fresh surface water overlying a warmer and saltier bottom water. The moored current measurements imply a persistent southwestward surface-intensified flow, consistent with previous studies. We follow Thompson and Sheng (J. Geophys. Res. 102 (1997) 24 987) and use a linear statistical model to hindcast the time-varying shelf response to local wind and remotely generated free waves propagating along the shelf. The wind is assumed to be spatially uniform and equal to that observed at Sable Island. The remote forcing is represented by subtidal sea level observations at Halifax after removal of local wind and density effects. Sable Island stress, on average, accounts for about 25% of the subtidal current variance. Sable Island wind and Halifax sea level together account for about 50% of the variance. The vertical shears in the mean alongshore currents agree reasonably well with the thermal wind relationship, indicating the importance of baroclinic effects during this period