SYMPHONIE is an ocean model developed by the SIROCCO system group (CNRS & Toulouse University).

  • Physical frame: Boussinesq Hydrostatic, free surface.
  • Horizontal Grid: C curvilinear.
  • Vertical grid: sigma generalized.
  • Numerical method: finite differences + energy conserving (Marsaleix et al 2008).
  • Time stepping scheme: Leap Frog + LP/FD filters (Marsaleix et al, 2012).
  • PGF: Pressure Jacobian (Marsaleix et al, 2009).
  • EOS: TEOS10 (Marsaleix et al, 2011).
  • Lateral boundaries: (Marsaleix et al, 2006).


Model description:

Symphonie is a Boussinesq hydrostatic ocean circulation model developed by the SIROCCO group. Momentums and tracers are computed on an Arakawa curvilinear C-grid using an energy conserving finite difference method described in Marsaleix el al. (2008). The time stepping method consists of a Leap Frog scheme combined to a Laplacian filter (Marsaleix et al, 2012). The Bentsen et al (1999) horizontal curvilinear Grid is used to increase the horizontal resolution near the coast, meanwhile covering a large area at a reasonable cost while a generalized terrain following coordinate is used for the vertical levels. Meanwhile, the well known sigma coordinate errors reported in Auclair et al (2000) led to the use of a suitable pressure gradient scheme (Marsaleix et al, 2009, 2011). The K-epsilon turbulence closure scheme, including the wave-current effect, has been implemented according to Michaud et al (2012). The various boundary conditions (lateral open borders, river discharges, surface conditions) are discussed in Estournel et al (2009). The large scale forcing terms, included in the radiation conditions formulation, are provided by the daily outputs of the MERCATOR system based on the NEMO model (Maraldi et al, 2013). The high frequency barotropic forcing is provided by the FES2012 tidal model. The astronomical tide potential has been implemented in the momentum equations according to Pairaud et al (2008). The air/sea fluxes are computed by the bulk formulae of Large et Yeager (2004) using the 3 hourly outputs of the ECMWF model.


Auclair F., Marsaleix P. and Estournel C., 2000 Sigma coordinate pressure gradient errors : evaluation and reduction by an inverse method. Journal of Atmospheric and Oceanic Technology, 17, 1348-1367. doi: 10.1175/1520-0426(2000)017<1348:SCPGEE>2.0.CO;2

Bentsen, M., Evensen, G., Drange, H., Jenkins, A.D. 1999 Coordinate Transformation on a Sphere 445 Using Conformal Mapping. Monthly Weather Review, 127, 2733-2740

Estournel C., Auclair F, Lux M., Nguyen C., Marsaleix P., 2009. “Scale oriented” embedded modeling of the North-Western Mediterranean in the frame of MFSTEP. Ocean Science, 5, 73-90

Large, W. G. and Yeager S. G.: Diurnal to decadal global forcing for ocean and sea-ice models: the data sets and flux climatologies, NCAR Technical Note: NCAR/TN-460+STR, CGD Division of the National Center for Atmospheric Research, 2004.

Maraldi C., Chanut J., Levier B., Ayoub N., De Mey P., Reffray G., Lyard F., Cailleau S., Drevillon M., Fanjul E. A., Sotillo M. G., Marsaleix P. and the Mercator Research and Development Team, 2013. NEMO on the shelf: assessment of the Iberia–Biscay–Ireland configuration. Ocean Science, 9, 745–771.

Marsaleix P., Auclair F., Floor J. W., Herrmann M. J., Estournel C., Pairaud I., Ulses C., 2008. Energy conservation issues in sigma-coordinate free-surface ocean models. Ocean Modelling. 20, 61-89. P., Auclair F., Estournel C., 2009. Low-order pressure gradient schemes in sigma coordinate models: The seamount test revisited. Ocean Modelling, 30, 169-177.

Marsaleix P., Auclair F., Estournel C., Nguyen C., Ulses C., 2011. An accurate implementation of the compressibility terms in the equation of state in a low order pressure gradient scheme for sigma coordinate ocean models. Ocean Modelling, 40, 1-13

Marsaleix P., Auclair F., Duhaut T., Estournel C., Nguyen C., Ulses C., 2012. Alternatives to the Robert-Asselin filter. Ocean Modelling, 41, 53-66

Michaud H., Marsaleix P., Leredde Y., Estournel C., Bourrin F., Lyard F., Mayet C., Ardhuin F., 2012. Three-dimensional modelling of wave-induced current from the surf zone to the inner shelf. Ocean Science, 8, 657-681

Pairaud I. L., Lyard F., Auclair F., Letellier T., Marsaleix P., 2008, Dynamics of the semi-diurnal and quarter-diurnal internal tides in the Bay of Biscay. Part 1: Barotropic tides, Continental Shelf Research, 28, 1294-1315

Examples of simulations done with SYMPHONIE

Smodel fukushima nucleid dispersion
Fukushima nucleide dispersion (values have no dimension and are not representative)












Surface current over Gulf of Lion simulated by S
Surface circulation averaged over January 2011.







Floats trajectories simulated by S
Surface float trajectories


Dense water formation of the shelf in the Gulf of Lion
Deep Water formation on the Gulf of Lion continental shelf.