The CMCC–CESM–NEMO is the physical basis of the new CMCC Earth System Model (CMCC-ESM). It is a global coupled climate model derived from the NCAR coupled model CESM version 1.1.2 (Hurrell et al., 2013), where the ocean component is NEMO (Madec et al., 2012) rather than the NCAR ocean model. In CMCC-CESM-NEMO all the climate components (atmosphere, ocean, land and sea-ice) are fully coupled.

The technical description of the coupling of NEMO with CESM is described in detail in the CMCC Research Paper RP0248. The philosophy of the coupling follows from that of CESM, and the model can be configured in a number of different ways from scientific and technical perspectives. It supports many resolutions and has the flexibility to set up simulations with different component configurations and parallel decompositions, which allow it to run from a single model in standalone forced configuration to the fully coupled system. The physical components of the CMCC-CESM-NEMO model are CAM5 for the atmosphere, CLM4.0 for the land surface, NEMO3.4 for the ocean and CICE4 for the sea-ice. CAM5 is the official atmospheric component of the NCAR CESM1 and it represents the first version of the community atmospheric model that is able to simulate the cloud-aerosol indirect radiative effects (Neale et al., 2012). CLM4 is the updated version of the community land model and it deals with the representation of terrestrial ecosystems through their cycling of water, energy, chemical elements and trace gases (Lawrence et al., 2011). Atmospheric and land components share the same horizontal grids. NEMO3.4 is an updated version of the Nucleus for European Modelling of the Ocean (NEMO; Madec et al., 2012) ocean general circulation model. In the horizontal direction the model uses a nearly isotropic curvilinear orthogonal grid with an Arakawa C–type three-dimensional representation of variables. In global configurations, we use tripolar ORCA-like grids (based on Mercator projection), which have a pole in the Southern Hemisphere collocated with the geographic South Pole and two poles placed on land in the Northern Hemisphere (in Siberia and Canada) in order to overcome the North Pole singularity. At the moment two horizontal grids are available and have been tested: a lower 1 resolution (ORCA1) and a higher, eddy-permitting, 1/4 resolution. CICE4 is the 4th version of the Community Ice CodE (Hunke and Lipscomb, 2008) and it includes parameterizations for thermodynamics, elastic-viscous-plastic dynamics and sub-grid scale representation of the ice thickness.

References:

• Hunke, E. C., Lipscomb, W. H. (2008) Cice: the los alamos sea ice model documentation and software user’s manual. Tech. rep., T-3 Fluid Dynamics Group, Los Alamos National Laboratory, Los Alamos NM 87545.
• Hurrell, J. W., Holland, M. M., Gent, P. R., Ghan, S., Kay, J. E., Kushner, P. J., Lamarque, J.-F., Large, W. G., Lawrence, D., Lindsay, K., Lipscomb, W. H., Long, M. C., Mahowald, N., Marsh, D. R., Neale, R. B., Rasch, P., Vavrus, S., Vertenstein, M., Bader, D., Collins, W. D., Hack, J. J., Kiehl, J., and Marshall S. (2013) The community Earth system model: a framework for collaborative research, B. Am. Meteorol. Soc., 94 1339–1360, doi: 10.1175/BAMS-D 12-00121.1
• Lawrence, D. M., Oleson, K. W., Flanner, M. G., Thornton, P. E., Swenson, S. C., Lawrence, P. J., Zeng, X., Yang, Z.-L., Levis, S., Sakaguchi, K., Bonan, G. B., and Slater, A. G. (2011) Parameterization improvements and functional and structural advances in version 4 of the Community Land Model, J. Adv. Model. Earth Syst., 3, M03001, doi: 10.1029/2011MS000045.
• Madec G and the NEMO team (2012) NEMO ocean engine version 3.4. Note du Pole de la Modelisation de l’Insitut Pierre-Simon Laplace No 27 ISSN no 1288-1619
• Neale R and co-authors (2012) Description of the NCAR Community Atmosphere Model (CAM5.0). NCAR/TN-486+STR, NCAR Technical Note (http://www.cesm.ucar.edu/models/cesm1.0/cam/docs/description/cam5_desc.pdf
• Fogli PG, Iovino D (2014) CMCC–CESM–NEMO: toward the new CMCC Earth System Model. CMCC Research Paper RP0248