NEAR-SURFACE RECIRCULATION OVER GEORGES BANK

Satellite-tracked drifters with drogues centered near-surface (5 m) an d below the seasonal thermocline (50 m) were launched during late wint er and spring of 1988 and 1989 in the northern Great South Channel in the western Gulf of Maine to investigate the regional circulation as p art of the South Channel Ocean Productivity Experiment (SCOPEX). Many of the near-surface drifters became entrained in the clockwise gyre ov er Georges Bank, and eight drifters made a total of 16 complete circui ts around the bank during the stratified season. The average recircula tion period of these eight drifters was 48 days, and the average drift er speed around the bank was 12 cm s(-1). There is no clear evidence f rom the drifter data that the strength of the clockwise gyre over the bank increased with time during the stratified season. On average, the se drifters (i) followed a relatively narrow path around the bank, exc ept over the eastern end of the bank where three preferred paths were observed, (ii) moved fastest over the northern and southern hanks of t he bank, (iii) did not enter a core area of 3500 km(2) centered at 41 degrees 17'N, 68 degrees 00'W, approximately 30 lan southwest of the t opographic center of the bank, and (iv) stopped circling the bank by t he end of November, due in part to strong wind events that appeared to drive drifters off the bank. Curiously, none of the near-surface drif ters moved from the southern flank of Georges Bank onto the New Englan d shelf as might be expected from continuity of flow along the outer s helf; instead, the drifters that circled the bank tended to move off t he bank along its southern hank. None of the drifters with drogues cen tered at 50 m appeared to recirculate around Georges Bank. Copyright ( C) 1996 Elsevier Science Ltd.