Coupling NEMO global ocean with hemispheric Arctic and Antarctic ice models

Two new NEMO-SAS (stand alone surface module) configurations are derived from a global ORCA grid. A FORTRAN tool is developed to transform the ORCA input files and define the OASIS weights & addresses to map fluxes and surface variables between one global and two hemispheric grids. A tri-component coupled system is set up, including an ocean on the ORCA2 global grid and two hemispheric NEMO-SAS with SI3 sea-ice. Removing North Pole folding communications in ice model helps to improve computing performance, since our ORCA2 coupled configuration is twice faster and two times cheaper than its single executable counterpart. The North Pole folding free hemispheric grid discretisation simplifies the coding of the future neXtSIM model, while relying on the same grid points than the ocean, thus avoiding inaccurate interpolation between ice and ocean grids