A Meddy off Cape St. Vincent. Part I: Description

Abstract

A meddy, an eddy formed from Mediterranean source water, was surveyed in detail with two types of expendable profilers and a CTD instrument. The muddy comprised two distinct, vertically aligned tenses with a combined thickness of 650 m. Both lenses were stratification minima. The upper lens was warmer, fresher (12.25°C, 36.5 psu), and more circular., the lower lens was cooler, more saline (12.1°C, 36.65 psu), and more elliptical, oriented alone a northeast by southwest line. The upper lens, homogeneous out to a radius of 6 km, had a radius of maximum velocity of 9 km. Its relative vorticity was ?0.85 f, and its Ertel potential vorticity, 4 ? 10?12 (m s)?1, was 17 times below ambient levels due to the combined effects of negative relative vorticity and vortex stretching. The meddy contained more kinetic energy than available potential energy (energy Burger number of 2.5). Compared with historical meddies, it had a larger Burger number and a more negative vorticity Rossby number.