QUASI-SYNOPTIC MESOSCALE VARIABILITY IN THE BALEARIC SEA

The circulation and dynamics of the Balearic Sea, a sub-basin of the W estern Mediterranean located between the Iberian peninsula and the Bal earic Islands, are characterized by a significant temporal and spatial variability induced by two well defined shelf/slope fronts over the c ontinental and island slopes. To establish the importance of the mesos cale features frequently observed, a quasi-synoptic AXBT survey of the Balearic Sea was carried out in only three days with a horizontal res olution of 18 km. An objective analysis technique for quantitative sca le separation was used to investigate the spatial variability of the t emperature field. At the sub-basin scale, the primary feature is the B alearic Front that separates cold Mediterranean waters from warmer wat ers of Atlantic origin. The front is located over the islands slope an d is characterized by a well defined meandering structure that appears to be strongly correlated with bottom topography. Strong mesoscale ac tivity is also found, mostly in the Balearic frontal region, with two small eddies embedded within the meanders and a warm filament overshoo ting towards the open sea. These energetic mesoscale features appear i n the upper 150 m and strongly modify the almost permanent relatively weak sub-basin scale circulation. The relationship between these insta bilities and local topography/coast irregularities is also suggested.