quoted from:https://doi.org/10.1175/JTECH1930.1

Most numerical coastal ocean circulation studies are based on models solving the Navier–Stokes equations on a vertically staggered C grid using classical finite-difference methods. These models generally have a free surface and sigma terrain-following coordinate, and use the Boussinesq and hydrostatic approximations. In this paper, modeling is carried out with the Symphonie model, a description of which, together with recent examples of applications, can be found in Ulses et al. (2005), Pairaud and Auclair (2005), Petrenko et al. (2005), and Estournel et al. (2005). With the exception of the variables of the turbulence closure scheme (Gaspar et al. 1990), this model is based on six variables, (u, υ, w, T, S, η), computed using the following equations. Momentum and continuity equations are given by