Tidal and buoyancy‐driven currents in Chignecto Bay, Bay of Fundy

Abstract

Circulations in the Chignecto Bay system (upper part of the Bay of Fundy) were studied using current meter moorings, tidal and diagnostic models, and salinity and suspended sediment concentration measurements. The current meter observations revealed that (1) the tides behaved basically as standing waves (tidal current leads tidal elevation by about 90°); (2) tidal currents were typically of the order of 1 m s−1 and were almost rectilinear; (3) residual currents were up to 0.17 m s−1 and the circulation pattern was quite complex; and (4) a two‐layer residual circulation with inflow in the upper layer and outflow in the lower layer existed at the entrance to the bay. Most of the residual currents in the upper part of the bay were driven by tidal rectification. The two‐layer residual circulation at the bay entrance was examined using a diagnostic model. It was found that the circulation was probably induced by horizontal density variations. Near the entrance to Cumberland Basin, Shepody Bay, and Chignecto Bay, the cross‐channel variation of surface suspended sediment concentration was consistent with the observed residual currents from current meter moorings and the estimated currents from the diagnostic model. The cross‐channel variation of salinity near the entrance to Chignecto Bay was also consistent with the observed and computed residual currents.