DIRECT EVIDENCE OF MEDDY FORMATION OFF THE SOUTHWESTERN COAST OF PORTUGAL

The formation of a Mediterranean Water eddy, or meddy, was observed di rectly for the first time off the southwestern coast of Portugal near Cape St. Vincent. The formation event is revealed in the 30-day trajec tory of a RAFOS float deployed in the lower core of the Mediterranean Undercurrent in the Gulf of Cadiz. For the first several days after de ployment, this float was advected westward in the Undercurrent at a sp eed of about 0.4 m s(-1), generally paralleling the topography. Just a fter passing Cape St. Vincent, where the coast turns abruptly northwar d, the float began looping anticyclonically, indicating that it had be come trapped in the core of a new meddy. The meddy translated first we stward, then southwestward along the southern flank of Gorringe Bank. The float rotated around the meddy center with azimuthal speeds of 0.2 -0.25 m s(-1) at a radius of about 10 km. The rotation period was on t he order of three days, and the average translation speed of the meddy over 25 days was 0.08 m s(-1). Observations of this and four addition al 30-day trajectories indicate (1) persistent westward Bow of the Und ercurrent along the south coast of Portugal, (2) a tendency for the lo wer core of the Undercurrent to separate from the continental boundary after passing Cape St. Vincent, and (3) evidence of anticyclonic loop ing west of Cape St. Vincent. These preliminary results confirm the sp eculation that the region off Cape St. Vincent is one site of meddy ge neration.