The Seasonal and Interannual Variability in the Ligurian-Povencal Basin

The circulation characteristics of the Ligurian-Provençal Basin are examined for the purpose of evaluating the possible forcings and the principal oscillations of the basin circulation. A critical review of the literature and available data (including model- simulation) indicates that the atmospheric-climatic conditions in winter are the principal factor conditioning the basin circulation. According to the field observations, these conditions generate different thermohaline properties in the Ligurian-Provençal Basin and the adjacent Tyrrhenian Sea. The gradient thus generated induces a winter outflow of warmer Tyrrhenian water through the Corsica Channel and then a seasonal oscillation of the Ligurian-Provençal Current. Though less evident, another seasonal oscillation seems to be present in the Ligurian-Provençal current system. This is visible along the western side of Corsica where it is shown as a progressive increase of the current velocity that reaches a maximum in early summer. This corresponds to the seasonal increase of the current indicated by a numerical model driven by deep water formation. We therefore suggest that this oscillation might represent the signal of the deep water formation on the boundary circulation.