The Mid-Ocean Dynamics Experiment

• Published in: Deep Sea Research
• Main Author: Zenk, Walter
• Format: Article in Journal/Newspaper
• Language: English
• Published: Pergamon 1978
• Subjects: North Atlantic
• Online Access: https://oceanrep.geomar.de/id/eprint/32869/; https://oceanrep.geomar.de/id/eprint/32869/1/Zenk_Mid-Ocean.pdf; https://doi.org/10.1016/0146-6291(78)90632-X

The Mid-Ocean Dynamics Experiment (MODE-1) was designed to investigate mid-ocean mesoscale eddies. An intensive and extensive program of measurements in three spatial dimensions and time was undertaken in an area southwest of Bermuda from March through mid-July 1973. Principal components of the experiment were an array of moored current meters and temperature-pressure recorders, hydrographic stations, drifting neutrally buoyant floats at 1500 m tracked by SOFAR, and acoustic and electromagnetic profilers. During MODE-1 a smaller scale survey relying on ship-tracked neutrally buoyant floats, a conductivity-temperature (CTD) survey, and a moored current meter array, MINIMODE, was carried out. The experiment was preceded by MODE-0, consisting of measurements by a series of moored current meters and other instruments in the general area selected for MODE-1. MODE-1 observations were generally within a 300-km radius circle centered at 26°N, 69° 40′W, with a greater concentration of observations in the interior of the circle. The region covers varied topography, with a flat a byssal plain sloping upward to the continental rise in the western half and rough topography in the eastern half. Descriptive, dynamical, numerical results of the experiment are presented. It is concluded that mid-ocean eddies are part of an energetic and structured variability field superimposed on the weaker gyre-scale mean circulation. In the western North Atlantic there is a band of eddy variability of around 100-day period and 70-km scale in which currents are horizontally nearly isotropic; vertical scales are of the order of the depth. The experiment provided conclusive evidence of the existence of mid-ocean eddies and serves as the basis for future experiments, such as POLYMODE, to extend our knowledge of these systems.