Continental Shelf Research 21 (2001) 455–471 Barotropic aspects of the dynamics of the Gulf of Naples (Tyrrhenian Sea) Daniele Gravili a , Ernesto Napolitano b , Stefano Pierini c, * a Centro Oceanologico Mediterraneo, Via della Liberta `, 37. 90139 Palermo, Italy b ENEA, Divisione Clima Globale e Mediterraneo, Centro Ricerche Casaccia - F19, Sacco Postale 91, Via Anguillarese, 301. 00060 S. Maria di Galeria (Roma), Italy c Dipartimento di Fisica, Universita ` dell ’Aquila, Via Vetoio, 67010 Coppito (L ’Aquila), Italy Received 19 January 1999; received in revised form 15 December 1999; accepted 18 May 2000 Abstract Process-oriented studies are carried out in order to analyze barotropic dynamical features in the Gulf of Naples: gravitational normal mode oscillations (seiches) of the gulf and depth-averaged circulations induced directly by the wind and remotely by the large-scale Tyrrhenian circulation. The shallow water equations are solved numerically in a domain which includes the Gulf of Naples and an external buffer zone whose role is two fold: it is required 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 determine 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 corresponding to the main seiches are determined and the corresponding horizontal spatial structures are presented. Good agreement is found when comparing these numerical modelling results with tide gauge records. The wind and boundary-driven depth-averaged circulation in the gulf is then studied by imposing idealized 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 that a series of circulation schemes is obtained representing typical dynamic scenarios in the Gulf of Naples. The results are related to the observations and good agreement is found. # 2001 Elsevier Science Ltd. All rights reserved. Keywords: Barotropic dynamics; Numerical modelling; Shallow water equations; Seiches; Gulf of Naples; Tyrrhenian Sea *Corresponding author. Tel.: +39-0862-433081; fax: +39-0862-433033. E-mail address: stefano.pierini@aquila.infn.it (S. Pierini). 0278-4343/01/$ - see front matter # 2001 Elsevier Science Ltd. All rights reserved. PII:S0278-4343(00)00100-X