Two counterrotating eddies in the Eastern North Atlantic: Lagrangian observations

Abstract

The formation of a cyclonic cold-core eddy, separating from a branch of the North Atlantic current system at about 49° N and 21° W, could be observed during a hydrographic survey in April 1985. One month later the eddy was revisited, now 40 nautical miles northeastwards of its previous position and detached from its parent current. During a second hydrographic survey a neutrally buoyant SOFAR float was launched into the core of the eddy. The 9-months trajectory shows the signature of the cyclonic eddy for about 2 months. Later—after passing regions of strong horizontal shear—the float follows the movements of a counterrotating, i. e. anticyclonic mesoscale eddy. A discussion of the Lagrangian data will be given in this paper.