Low‐frequency current variability on the Labrador Shelf

Abstract

Current meter measurements from two locations on the northern part of the Labrador Shelf have been analyzed using empirical orthogonal function (EOF) analysis in the three frequency bands 0.09–0.18 cpd, 0.18–0.36 cpd, and 0.36–0.54 cpd. To describe the measurements in each frequency band, a numerical circulation model was developed for the shelf, driven by alongshore and onshore wind stresses and by flow through Hudson Strait. The latter flow is taken to arise from the atmospheric pressure variations over Hudson Bay and from the along‐static wind stress over Hudson Strait. The model appears to be quite successful in describing the circulation in the center frequency band. This suggests that the forcing within this band is primarily due to the alongshore wind stress over the shelf and to the flow through Hudson Strait. The model indicates that in the region of study, the mode 1 shelf wave dominates the velocity field over the upper part of the shelf, whereas mode 2 dominates the flow near the shelf break. In the first and third frequency bands the model is less successful in describing the measured currents. It is likely that this failure is at least in part due to the neglect of other forcing mechanisms, such as shelf waves propagating southward out of Baffin Bay.