Currents and dispersion in the abyssal Northeast Atlantic. Results from the NOAMP field program

Abstract

The NOAMP field program, carried out in the deep Northeast Atlantic from 1983 to 1986, was designed to investigate the local deep flow and the dispersion of suspended material by means of current meter, SOFAR float, turbidity and CTD data. The bottom topography of the NOAMP area (45-49°N, 17-23°W) represents a highland with hills and ridges rising up to 1000 m above the deep-sea floor (approx. 4500 m). The deep mean flow (3-5 cm s-1) runs fairly parallel to the depth contours and consists of a system of small topographically induced gyres that can trap any kind of passive admixture. During the first 50 days after release, a cluster of 14 deep-sea floats drifting at depths of around 3500 m spread steadily over an area with a diameter of about 300 km. During the following roughly 200 days a further drift of the centre of mass of the cluster-as well as a further spreading relative to the centre of mass-was hardly noticeable. Occasionally, high energetic events (benthic storms) with durations between 3 and 27 days, and maximum velocities up to 27 cm s-1 occurred directly above the deep-sea floor. © 1992.