Assessment of Georges Bank recirculation from Eulerian current observations in the Great South Channel

Twenty Vector Averaging Current Meters (VACMs) were deployed at various depths in the vicinity of the Great South Channel during several experiments conducted between 1976 and 1986 (average record length ∼ 5 months). Since little more than mean current vectors from some records has been reported previously, a basic description of the flow field is presented here. With at least one current record occurring in every month of the year, the hypothesis of increased subtidal flow around Georges Bank during the stratified season is supported. Anemometer data obtained at nearby NOAA environmental buoys and the Nantucket Lightship are used to estimate wind stress, the primary forcing in the well-mixed season. Empirical modes of current structure demonstrate the spatial structure and the seasonal variability of wind and density-driven dynamics in this region. When averaged over a few months, the northward transport through the Great South Channel (fall mean ∼ 0.095 Sv) is small compared to the westward transport along the southern flank of Georges Bank (fall mean ∼ 0.421 Sv), but the subtidal variability of the Great South Channel transport is highly energetic, with a standard deviation (∼ 0.11 Sv) greater than the mean, indicating that large reversals in transport can occur over a few days.