Temporal variability of the subarctic front near the Charlie-Gibbs fracture zone

We document temporal variability of the northernmost branch of the North Atlantic Current, known as the North Subarctic Front (NSAF), for the period 1976-1985. The front's location and temperature-salinity (T-S) parameters were determined from 120 repeat transects along three standard sections occupied by Russian ships: (1) ocean weather station (OWS) ''C'' (52.75 degrees N, 35.5 degrees W) to St. John's, Newfoundland; (2) along 35 degrees W, from 52 degrees N to 36.5 degrees N; and (3) OWS C to Cape St. Vincent, Portugal. The NSAF exhibits significant interannual variability of its location, shifting 200 km to 300 km in a few months. Along the OWS C-St. John's section, the front reached its southernmost location in 1976-1977, then experienced two 250-to-300-km northward shifts, in 1978-1979 and 1980-1981; all of the three shifts peaked in wintertime. These events nearly coincide with events of the opposite sign along the OWS C-Cape St. Vincent section (the northernmost location in 1976-1977 and two 200-km southward shifts, in 1978-1979 and 1980-1981). The NSAF's behavior is thus coherent near the Charlie-Gibbs Fracture Zone at the 500-km scale. Frontal time series (associated with the moving front) of T and S at the 200-m level for the cold side of the NSAF reveal two events: an S-200 minimum in the winter of 1976-1977, which might be a manifestation of the ''Great Salinity Anomaly'' of the 1970s, and a sharp drop of S-200 in early 1984, which might signal the arrival of another large salinity anomaly, the ''Great Salinity Anomaly'' of the 1980s.