The new dynamical core solves the system of equation in grid point space on the icosahedral grid, which allows
ICON GCM: ICOsahedral Non-hydrostatic General Circulation Model.
The ICON dynamical core is a new development initiated by the Max Planck Institute for Meteorology (MPI-M) and the Deutscher Wetterdienst (DWD). This dynamical core will combine several properties, which are considered important for future progress in numerical weather forecasting at DWD or climate research at MPI-M.
In particular the ICON dynamical core will solve the fully
compressible non-hydrostatic equations of motion for simulations at
very high horizontal resolution. The discretization of the continuity
and tracer transport equations will be consistent so that mass of air
and its constituents are conserved, which is a requirement for
atmospheric chemistry. Furthermore, the vector invariant form of the
momentum equation will be used, and thus, vorticity dynamics will
emphasized.
The
new dynamical core solves the system of equation in grid point space
on the icosahedral grid, which allows
the quasi-isotropic horizontal resolution on the sphere, and
the restriction to regional domains.
The choice of triangular cells given by the Delaunay triangulation allows C-grid type discretization and straightforward local refinement in selected areas, in the global as well as regional framework. The figure shows a global grid with two refinement steps centered on ca. 10°E/45°N.
Alternative grid options for ICON are also intended: These comprise the hexagonal C-grid as an alternative to the triangular version, and a quadrilateral regional version for simplified comparison with existing limited area models.
Models
An overview of the different “ICON”-models is shown in the sidebar. Before we started to tackle three dimensional flows, a shallow water model was developed as a test bed for gaining experience with unstructured grids, investigate grid optimizations and evaluating necessary numerical operators. Currently, the ICON development splits up into branches of ocean and atmospheric models, which will use the same grid and operators, but diverge otherwise. For both, ocean and atmospheric development, hydrostatic dynamical cores were the next development step. Currently and in the near future we will focus more on the non-hydrostatic versions.
(ags, 27.10.2008)