AIR-SEA INTERACTION MEASUREMENTS IN THE WEST MEDITERRANEAN-SEA DURING THE TYRRHENIAN EDDY MULTI-PLATFORM OBSERVATIONS EXPERIMENT

Measurements of radiative fluxes were carried out in the Tyrrhenian Sea in fall and winter as part of the Tyrrhenian Eddy Multi-Platform Observations Experiment (TEMPO). These measurements have supplied the first experimental radiation data set over this basin. Seasonal variation of the different components of the budget are investigated. Since data collection was carried out in an area in which a quasi-permanent eddy is present, the behavior of the radiation parameters across the frontal zone is analyzed. The most interesting result of the air-sea interaction in proximity of a marine front consists in the covariation of sea surface temperature and downwelling long-wave radiation. Contemporaneous satellite data show a clear correlation between sea surface structure and horizontal distribution of columnar atmospheric water content. Therefore this inhomogeneity clearly is one of the main factors responsible for the variation of the downwelling radiation across the front. A comparison between experimental data and results of some of the most widely used bulk formulae is carried out for both short- and long-wave radiation. The mean difference between measured and empirical solar radiation values is less than 3%, while in the case of the net long-wave radiation budget, poor agreement is found. Indeed, a 30 W/m2 bias results from the comparison. This discrepancy is consistent with the imbalance between previous bulk calculations of total heat budget at the surface and corresponding hydrographical observations of heat exchange at Gibraltar.