Interannual variability of boundary fluxes and water mass properties in the Gulf of Maine and on Georges Bank: 1993–1997☆☆☆

摘要: Abstract Analysis of three years (October 1993–September 1996) monthly mean current, temperature and salinity observations from moorings in the major Gulf Maine (GOM) inflows off southwest Nova Scotia (C2) Northeast Channel (NECE) reveals some new features annual NECE cycles, including (1) a peak near-surface ( 75 m) inflow, followed by later episodes enhanced cold, fresh inflow at C2 shallow NECE. Generally, flow rates deep were out phase, with increased (deep NECE) associated reduced cooler, fresher (warmer,saltier) conditions both sites. Freshwater transport anomalies to are maximum surface layers largely negative(positive) over first(last) half measurements. The timing these freshwater variations is consistent observed fluctuations hydrographic measurements GOM GB, which reached salinities late 1994, then declined through 1995–1996. Oxygen isotope analysis suggests that almost all water present on central cap GB 1996 early 1997 northern (Scotian Shelf) origin as opposed 1994 1995 when River Waters contributed 38 26%, respectively, (relative 34.8) cap. A simple box model driven changes boundary fluxes indicates last measurement period (April 1995–September 1996), volumetric rate 10 5  m 3  s −1 (roughly 17% total transport, 5.83×10 ), produced net decrease 0.73 outflow waters. Average transports C2(NECE) roughly twice(half) those 1970s, but climtological estimates. change exceeds climatological estimate. Examination possible local remote sources confirms 1996–1997 anomaly Labrador Sea/Baffin Bay results exceptionally cold winters 1990s. similar event 1980s their occurrence part quasi-decadal climate signal follows North Atlantic Oscillation (NAO).