Barotropic aspects of the dynamics of the Gulf of Naples (Tyrrhenian Sea)

Process-oriented studies are carried out in order to analyze barotropic dyn amical features in the Gulf of Naples: gravitational normal mode oscillatio ns (seiches) of the gulf and depth-averaged circulations induced directly b y the wind and remotely by the large-scale Tyrrhenian circulation. The shal low water equations are solved numerically in a domain which includes the G ulf of Naples and an external buffer zone whose role is two fold: it is req uired to remove the effect of a fictitious boundary in the determination of the seiches and it allows the imposition of boundary conditions related to the large-scale circulation in the Tyrrhenian Sea, which contributes to de termine the internal circulation via topographic coupling. The seiches are studied by means of a spectroscopic analysis in which eigenoscillations are generated by the relaxation of a wind setup. The eigenperiods correspondin g to the main seiches are determined and the corresponding horizontal spati al structures are presented. Good agreement is found when comparing these n umerical modelling results with tide gauge records. The wind and boundary-d riven depth-averaged circulation in the gulf is then studied by imposing id ealized local winds and external currents chosen on the basis of realistic modelling of the wind-driven circulation of the Tyrrhenian Sea. Both quasi- steady and typical transient-time dependence are taken into account, so tha t a series of circulation schemes is obtained representing typical dynamic scenarios in the Gulf of Naples. The results are related to the observation s and good agreement is found. (C) 2001 Elsevier Science Ltd. All rights re served.