Ocean circulation and sea ice distribution in a finite element global sea ice -- ocean model

A newly developed global Finite Element Sea IceOcean Model (FESOM) is presented. The ocean componentis based on the Finite Element model of the North Atlantic (FENA) but has been substantiallyupdated and extended. In addition to a faster realization of the numerical code, state-of-the-art parameterizationsof subgrid-scale processes have been implemented. A Redi/GM scheme is employed toparameterize the effects of mesoscale eddies on lateral tracer distribution. Vertical mixing and convectionare parameterized as a function of the Richardson number and the MoninObukhov length. A finiteelement dynamic-thermodynamic sea icemodel has been developed and coupled to the ocean component.Sea ice thermodynamics have been derived from the standard AWI sea ice model featuring a prognosticsnow layer but neglecting internal heat storage. The dynamic part offers the viscous-plastic andelastic-viscous-plastic rheologies. All model components are discretized on a triangular/tetrahedral gridwith a continuous, conforming representation of model variables. The coupled model is run in a globalconfiguration and forced with NCEP daily atmospheric reanalysis data for 19482007. Results are analysedwith a slight focus on the Southern Hemisphere. Many aspects of sea ice distribution and hydrographyare found to be in good agreement with observations. As in most coarse-scale models, Gulf Streamtransport is underestimated, but transports of the Kuroshio and the Antarctic Circumpolar Current appearrealistic. The seasonal cycles of Arctic and Antarctic sea ice extents and Antarctic sea ice thickness arewell captured; long- and short-term variability of ice coverage is found to be reproduced realisticallyin both hemispheres. The coupled model is now ready to be used in a wide range of applications.