Structure and transport of alongshelf currents across the southern flank of Georges Bank during late summer, 1982

An array including seven moorings was in place between 10 August and 25 Sep tember 1982 on southern Georges Bank. Tell of the records from the Vector-A veraging Current Meters (VACMs) were complete. Short-term drifters with win dow-shade drogues at 10 m seaward of the shelfbreak (200 m) documented flow of shelf water across bathymetry. Winds were available for this period fro m NOAA buoy 44003 at the southwestern corner of Georges Bank near the array . The major structure in the subtidal flow is an alongshelf maximum toward th e west (mean speed similar to 27 cm s(-1) with bursts often > 30 cm s(-1)) at the shelfbreak front (similar to 100 m): the shelfbreak jet. The first t wo modes in empirical orthogonal analysis of the cross-bank structure conta in 82% of the variance. Mode I is associated with the large-scale alongshel f current and is partially correlated with local winds. Mode 2 generally no t correlated with wind, may be generated by features initiated by the Cull stream. The current record at the northern periphery of the warm eddy or re mnant of a warm-core ring has a mean velocity of 5 cm s(-1) toward the east for the period, opposite the general circulation over the shelf. Elsewhere the circulation over the shelf seemed minimally affected even with the pro ximity of the offshore feature. A mean estimate for volume transport of she lf water during the period is 0.83 +/- 0.2 Sv with periods of greater than 1 Sv related to NE winds leading by 6 h. While a bias is possible due to un dersampling of the velocity field, this mean value and variability during l ate summer are higher than previously reported estimates for transport of s helf water. This is primarily due to the additional contribution of the she lfbreak jet near the 100 m isobath, Confidence limits for the transport wer e calculated by two independent methods, geometric weighting and block esti mation by universal kriging. (C) 2000 Elsevier Science Ltd. All rights rese rved.