  Subsurface float and moored observations are presented to show for the first
time the formation and propagation of anticyclonic submesoscale coherent
vortices that transport relatively cold, fresh subpolar water to the interior
subtropical North Atlantic. Acoustically tracked RAFOS floats released in the
southward-flowing Western Boundary Current at the exit of the Labrador Sea
reveal the formation of three of these eddies at the southern tip of the Grand
Banks (42 N, 50 W). Using a recently developed method to detect eddies in float
trajectories and estimate their kinematic properties, it was found that the
eddies had average rotation periods of 5--7 days at radii of 1025 km, with mean
rotation speeds of up to 0.3 m/s. One especially long-lived (5.1 months) eddy
crossed under the Gulf Stream path and translated southwestward in the
subtropical recirculation to at least 35 N, where it hit one of the Corner Rise
Seamounts. Velocity, temperature and salinity measurements from a nine-month
deployment of two moorings south of the Gulf Stream at 38 N, 50 W reveal the
passage of at least two eddies with similar hydrographic and kinematic
properties. The core temperature and salinity properties of the eddies imply
their formation at intermediate levels of the Labrador Current south of the
Tail of the Grand Banks. These observations confirm earlier speculation that
eddies form in this region and transport anomalously cold, low-salinity water
directly into the subtropical interior. Possible formation mechanisms and
potential importance of these eddies to interior ventilation and the
equatorward spreading of Labrador Sea Water are discussed.
