F. Lemarié, L. Debreu, F. Auclair, N. Ducousso, F. Dumas, R. Benshila:

Recent Developments around the CROCO Initiative for Complex Regional to Coastal Modeling


CROCO (Coastal and Regional Ocean Community model [1]) is a new structured-grid oceanic modeling system built upon the dynamical kernel of the AGRIF version of ROMS (see [2] for a description of the various ROMS kernels). An objective behind CROCO is to aggregate recent achievements of the french regional/coastal modeling community including the pseudo-compressible non-hydrostatic (NH) capability of SNH [3] (and an incompressible alternative from [4]), the MUd and Sand TrAnsport modelliNG (MUSTANG) sediment dynamics module of Mars3D, as well as a newly developed multi-resolution capability based on a multigrid approach, etc. The implementation of both the multiresolution and pseudo-compressible NH features have been facilitated by a revision of the way the dissipation necessary to stabilize the time-integration of the baroclinic/barotropic mode-splitting is imposed [5].

The talk will thus focus on three original features which have been implemented in the CROCO model during the last few months and which are of interest for the coastal ocean modeling community:

1- A much reduced numerical dissipation to stabilize the baroclinic/barotropic mode-splitting

2- A 3-mode time-splitting approach relaxing the Boussinesq and hydrostatic assumptions

3- A truly multiresolution strategy as an alternative to unstructured strategy

The benefits of each of these numerical developments will be illustrated by idealized and realistic simulations. Finally, some thoughts on the computational efficiency of oceanic models and how it relates to numerical methods as well as future challenges and perspectives will be given. 


[1]  http://www.croco-ocean.org
[2]  Shchepetkin A. and J.C. McWilliams Correction and commentary for ocean forecasting in terrain-following coordinates: formulation and skill assessment of the Regional Ocean Modelling System by Haidvogel et al.. J. Comp. Phys. (2009)
[3]  Auclair F., L. Bordois, Y. Dossmann, T. Duhaut, A. Paci, C. Ulses, and C. Nguyen. A non-hydrostatic non-Boussinesq algorithm for free-surface ocean modelling. Ocean Modell., in revision (2018)
[4]  Roulet G., M. Molemaker, N. Ducousso, and T. Dubos. Compact symmetric Poisson equa- tion discretization for non-hydrostatic sigma coordinates ocean model, Ocean Modell. (2017)
[5]  Demange, J., L. Debreu, F. Lemarié, P. Marchesiello and E. Blayo Stability analysis of split-explicit oceanic models. J. Comp. Phys., submitted, (2018)