On the geographic and seasonal patterns of the near-surface circulation onGeorges Bank - from real and simulated drifters

We examine the near-surface circulation on Georges Bank by comparing data c ollected from satellite-tracked drifters in the real ocean and data compute d for simulated drifters in a virtual ocean. The observed trajectory data s et was obtained from drifters drogued at 10 m during the 1995-1997 US GLOBE C Northwest Atlantic/Georges Bank field program. The simulated drifter traj ectories were computed based upon the seasonal circulation as predicted by the Dartmouth Circulation Model, using bimonthly climatological forcing. Th e observed and simulated drifter patterns indicate well-organized anticyclo nic around-bank flow on the northern flank, Northeast Peak, and southern fl ank throughout the year. The key to recirculation around the Bank is the se asonality of the northward flow in the Great South Channel. Winter months a re characterized by Little northward flow, while there is significant north ward flow in the Great South Channel in summer. In late summer, both observ ed and numerical drifters indicate a minimum recirculation time on Georges Bank of roughly 40 days. The simulated drifter trajectories generally predi ct a seasonal climate consistent with the observed drifters, though the eff ects of weather events on the observed drifters are not captured by the num erical simulations. (C) 2000 Elsevier Science Ltd. All rights reserved.