QUASI-SYNOPTIC MESOSCALE VARIABILITY IN THE BALEARIC SEA

The circulation and dynamics of the Balearic Sea, a sub-basin of the Western Mediterranean located between the Iberian peninsula and the Balearic Islands, are characterized by a significant temporal and spatial variability induced by two well defined shelf/slope fronts over the continental and island slopes. To establish the importance of the mesoscale features frequently observed, a quasi-synoptic AXBT survey of the Balearic Sea was carried out in only three days with a horizontal resolution of 18 km. An objective analysis technique for quantitative scale separation was used to investigate the spatial variability of the temperature field. At the sub-basin scale, the primary feature is the Balearic Front that separates cold Mediterranean waters from warmer waters of Atlantic origin. The front is located over the islands slope and is characterized by a well defined meandering structure that appears to be strongly correlated with bottom topography. Strong mesoscale activity is also found, mostly in the Balearic frontal region, with two small eddies embedded within the meanders and a warm filament overshooting towards the open sea. These energetic mesoscale features appear in the upper 150 m and strongly modify the almost permanent relatively weak sub-basin scale circulation. The relationship between these instabilities and local topography/coast irregularities is also suggested.