Modeling the Mean Circulation of the Labrador Sea and the Adjacent Shelves

Abstract

A linear three-dimensional diagnostic model is used to study several aspects of the mean circulation of the Labrador Sea and the adjacent shelves: volume transport, three-dimensional structure of currents, mesoscale features produced by JEBAR, winter surface current derived from ice drift data, difference between summer and winter circulation, and effects of buoyancy and local wind on the circulation. The summer circulation is forced by a sea surface elevation at the northern boundary, tuned to produce a 35 Sv (Sv≡106 m3 s?1) total southward transport (including the shelf, the Labrador Current, and the deep sea transports) across the Hamilton Bank section. A comparison of the model results with data collected over the shelves indicates that the model is able to reproduce the major features of the observations. Buoyancy effects on the circulation are found to be more important in the southern Labrador Sea than in the northern Labrador Sea. The subbasin-scale currents give rise to an alongshelf variation of the volume transport of the Labrador Current, 25 Sv in the northern Labrador Sea, 12 Sv at the Hamilton Bank section, and 25 Sv at the northeast Newfoundland shelf section. The winter circulation is calibrated with surface currents derived from ice drift data. The basin-scale transport at the Hamilton Bank section in the winter is 17?29 Sv greater than that in the summer. The effects of seasonally averaged local winds on the volume transport are found to be small.