MARS3D / AGRIF model configuration for the Bay of Brest

This repository provides the source code written in Fortran 90 language based on MARS3D model code (Lazure and Dumas, 2008) implemented with the AGRIF library (Adaptive Grid Refinement In Fortran from Debreu et al. (2008)). It also contains the bathymetric grids and the input namelist files.

The MARS3D/AGRIF model is setup over the Iroise sea (geographic limits 47.74°N - 48.82°N and 4.08°W - 5.55°W) with a horizontal grid resolution of 250m. A zoom over the Bay of Brest is introduced with a resolution of 50m (geographic limits 48.20°N - 48.44°N and 4.09°W - 4.72°W). The time and space refinement factors are both equal to 5. The vertical discretization is performed with 20 equidistant σ-layers in both grids. The timestep for mother grid is set to 30s which consequently leads to 6s for the child grid.

The bathymetries are interpolated from a combination of different digital terrain models (SHOM, Ifremer, IGN). The Iroise model is forced by harmonic components from the SHOM CST-France model (Le Roy and Simon, 2003). The 3D open boundary conditions for temperature and salinity are imposed at hourly frequency from a regional configuration based on a hindcast (Caillaud et al., 2016). Freshwater inputs for the four main rivers in the Bay were taken from the French HYDRO database and corrected with corresponding watershed surface rates

The horizontal turbulent closure consists of a Laplacian operator with a constant turbulent viscosity coefficient. This coefficient was set to 0.5 m2 s−1. The vertical turbulent closure is performed using the generalised length-scale parametrisation with a two-equation k-ε model.

For the child grid, the surface drag coefficient was set uniformly to obtain the optimum validation of the currents in the Bay of Brest. However, the bottom drag coefficient relied on the Prandtl theory of the bottom boundary layer and its logarithmical shape. It includes in its formulation a classical roughness scale, which was spatialised according to a recent sedimentological map (Gregoire et al. 2016).


Biological oceanography, Physical oceanography


Bay of Brest, hydrodynamic model, coastal dynamics


48.48696N, 48.149484S, -4.103159E, -4.935206W


Source code
13 MoFortran 90
How to cite
Petton Sebastien, Dumas Franck (2022). MARS3D / AGRIF model configuration for the Bay of Brest. SEANOE.

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