Site L SOFAR float experiment, 1982-1985

Abstract

Lagrangian measurements of low frequency currents in the vicinity of the Gulf Stream and its recirculation region in the western Sargasso Sea were made by tracking SOFAR floats. These floats were tracked using acoustic time of arrival information from an array of five Autonomous Listening Stations {ALSs) which were moored in the western Sargasso Sea. The ALSs performed almost flawlessly, returning over 90 percent of the possible data. Floats were released in three deployments of seven floats each in November 1982, February 1983, and June 1983. The floats were launched in initially coherent arrays (approximately 20 km spacing) at 34°N, 70°W, Site "L", and were ballasted for 700 m depth. The SOFAR floats themselves functioned with somewhat less than expected reliability; four floats failed fairly soon after launch, and several other floats suffered failures of their temperature and pressure telemetry. The majority of the SOFAR floats launched in this program produced long, and interesting trajectories. These new data will be valuable for estimating first order flow statistics in the dynamically important recirculation region, for visualizing interactions between the Gulf Stream and the New England Seamount Chain, and for estimating one and two particle diffusivities in a region of very high eddy energy.