Analysis of drifting SOFAR buoys in the Greenland Sea, 1989-1990

Abstract

In an attempt to gain a better understanding of the intermediate depth circulation of the Greenland Sea,16 SOFAR floats were launched into Fram Strait in 1988 and 1989. Between the fall of 1989 and the summer of 1990, five of these floats were tracked by autonomous listening stations (ALS) positioned to provide tracking in the southern portion of the Greenland Sea. One float (MZ86) provided tracking information for ten months of the ALS deployment period. The other floats provided tracking information ranging from several days to two months. These float tracks delineated the intermediate depth circulation around the Greenland Sea gyre. The MZ86 trajectory exited the Boreas Basin and crossed the Greenland Fracture Zone with a speed of approximately 17 cm s-1. Along the Greenland continental slope the flow increased to 28 cm s- 1 suggesting the presence of a bottom trapped boundary current. Near 74°N the trajectory turned eastward under the shallower warm core of the Jan Mayen Current at 4 cm s-1. This leg closed the Greenland Sea gyre and also shows evidence of interactions with filaments of the Norwegian Atlantic Current (NAC) coming through the Mohns Ridge at these intermediate depths. Two other floats demonstrated tracks which crossed the Mohns Ridge and drifted farther to the east, mixing with the waters of the NAC.