Statistical analysis of the surface circulation in the Algerian Current using Lagrangian buoys

The Algerian Current (AC) is one of the most energetic flows in the Mediter ranean basin. A characteristic picture of this current is formed by a serie s of mesoscale eddies at different scales. Here, statistical analysis of 15 surface Argos buoy tracks in 1996-1997 provides a complete Lagrangian view of the AC. The buoys, released upstream and across a coastal meander betwe en 0 degreesE and 1 degreesE longitude, were followed for 3 months. They tr avelled eastward at an average speed of 14 cm/s and showed high energetic f luctuations related to several mesoscale eddies. The characteristic integra l time and space scales are highly anisotropic. For the zonal component, th ese are about 4 days and 66 km, and for the meridional component, about 2 d ays and 26 km. Representative values of effective diffusivities from single dispersion statistics are within 0.7-1.3 X 10(8) and 1.5-6.0 X 10(7) cm(2) /s for the zonal and meridional directions, respectively. A local analysis shows that mesoscale motions are particularly relevant in the region 1-3 de greesE and 7-8 degreesE, provided the considerably high values of eddy kine tic energy in comparison with the mean kinetic energy. Eddy-mean current in teractions are evidenced by the significant changes of sign of horizontal c ovariance from west to east. Finally, an Eulerian picture of the AC is buil t, exhibiting similar trends than previous and recent field observations. ( C) 2001 Elsevier Science B.V. All rights reserved.