The role of topography in small well-mixed bays, with application to the lagoon of Mururoa

The present study aims to better understand how bathymetry and wind field interact to shape the circulation in well-mixed bays with particular emphasis on the lagoon of Mururoa. The simple model of Csanady (J. Phys. Oceanography 3 (1973) 429) is re-examined and some new analytical properties of the velocity distribution are derived. An extended version of the Csanady model, called the idealised model (IM), is then applied to the lagoon of Mururoa located in the Pacific. The circulation obtained by IM compares well with the circulation simulated by a three-dimensional hydrodynamic model. Our results show that IM provides a simple and powerful heuristic tool to gain more insight into the dominant dynamical regime of the lagoon.