Development of an Ocean-Atmospheric Model on Isocahedral Grids 
(Peter Korn, Max-Planck Institute for Meteorology, Hamburg, Model and Data Group).
 
The Isocahedral Non-hydrostatic General Circulation Model (ICON) is a
joint project with the German Weather Service.  It a the unified model for
global and regional modelling on an isocahedral grid. The ICON
structure separates numerics from physics, exploits similarities
between atmospheric and ocean equations and emphasizes
the conservation of discretized equivalents of global invariants.
Physical variables are defined on a locally refineable triangular grid,
the continous operators are discretized using the (Delaunay-Voronoi) duality
between the triangular grid and its associated hexagonal grid. Mass fluxes
out of the dual cell are specified and shallow water equations are integrated.
The numerical scheme conserves either enstrophy or energy, but not both.
The model was applied to discretized shallow water equations. Challenges
include mass conserving locally refinement while avoiding interface artefacts
and to overcome gridscale limitations upon the threshold of turbulence
modelling.