The Flux of Dense Cold Overflow Water Southeast of Iceland

Abstract

From the period commencing midsummer 1990 and lasting for 13 months, 13 current meters were deployed on seven moorings at depths between 1000 and 2300 m southeast of Iceland (63°09?N, 17°18?W to 61°44?N, 15°24?W). The purpose of the array (designated WOCE ACM8) was to measure the overflow of dense water, downstream of the source in the Faeroe Bank Channel and downstream of any sources on the Iceland?Faeroe Ridge. In the depth range 1300?2100 m three of the moorings showed a bottom intensified current that was persistent and directed to the southwest; at the other moorings the current was erratic and weak. The records were combined to form a transport time series for water denser than σ0>27.8 kg m?3 in the direction 240°. A mean value of 3.2 ± 0.5 Sv was found with considerable variability near a period of seven days, but there was no convincing evidence for a seasonal signal. The amount of pure Norwegian Sea water present in the overflow was estimated at 1.6 ± 0.15 Sv, close to previous determinations and comparable to that measured in the Faeroe Bank Channel. A small contribution is therefore deduced as crossing the Iceland?Faeroe Ridge. A general freshening of the water column in the northern Iceland Basin in the period 1960?1990 is demonstrated.