The role of winter intermediate waters in the spring-summer circulation of the Balearic Sea 1. Hydrography and inverse box modeling

Abstract

Hydrographic transects performed across the Balearic Sea (western Mediterranean) in June 1993 are used to estimate the absolute geostrophic flow by means of a linear inverse model, ensuring conservation of water properties (mass, salt, and heat) in closed boxes. The computed fluxes are supporting the concept that most of the northern waters that flow into the basin over the Spanish peninsula slope (≈1.1 Sv) recirculate back to the north in a cyclonic pattern while southern waters that enter through the Ibiza Channel, mainly modified Atlantic waters (≈0.5 Sv), transit to the north over the Balearic slope. Results point out that winter intermediate waters (WIW), distributed in several coherent mesoscale structures, play an active role in these dynamics. A major anticyclonic WIW eddy ("weddy") lying in the southern basin obstructs the water exchange through the Ibiza Channel and deflects the Continental Current back to the north. A similar though smaller weddy, strained by the Balearic Current into an elongated along-slope WIW filament, controls the circulation through the Mallorca Channel. All these results are discussed in the light of data collected during past years. Copyright 1999 by the American Geophysical Union.