1. ICON Bucharest 2006 J.Steppeler, Ripodas, Th. Heinze, D. Majewski (DWD - German Weather Service, Offenbach, Germany) L. Bonaventura (MOX - Politecnico di Milano, Italy) M. A. Giorgetta (Max Planck Institute for Meteorology, Hamburg, Germany)

2. Intro: Goals of the ICON project New unified weather forecasting (DWD) and climate model (MPI-M). Mass conservation + discr. continuity eq. = discr. transport eq. with c≡1 Quasi uniform horizontal resolution  icosahedral grids Local grid refinement in one or more regions  triangular cells Global or regional domain Hydrostatic, and non-hydrostatic Ocean GCM using same grid and data structures and numerical operators

3. Intro: Main participants DWD:Deutscher Wetterdienst, Germany D. Majewski, Th. Heinze, P. Ripodas, B. Ritter, H. Frank, D. Liermann, U. Schättler, J. Steppeler MPI-M:Max-Planck-Institute for Meteorology, Germany E. Roeckner, M. Giorgetta, L. Kornblueh, U. Schulzweida, P. Korn, H.Wan MOX – Politecnico di Milano, Italy L. Bonaventura Others: W. Sawyer (ETH Zürich), P. Sanders (Uni Karlsruhe), D. Steurer (MPI-I, Saarbrücken), J. Baudisch (TU München) Discussions and/or joint work: R. Klein, F.X. Giraldo, J. Klemp, D. Randall, T. Ringler, H. Tomita

4. ICON main line Grid structure based on Thuburn (1997) + optimization option (Heikes and Randall, 1995) 2 conservation variants: –Mass and potential vorticity conservative scheme –Mass and energy conserving scheme 2 or 3 time level semi-implicit time stepping ICON side line Grid structure based on great circle grids Uniform third order approximation Easy incorporation of ordinary grid conceps and existing local models

5. GME: 3 time level ICOSWP: 2 time level

6. Local zooming option: grid generation > Lat-Lon region > Circular region > 3 refinement leves > 3 refinement levels

7. NP=3 NP=4 NP=5 Cube 4-body Isocahedron Rhomboidal divisions of the sphere

8. Four points r1,r2,r3,r4 may have any position in space Divide the sides of the rhomboid equally and connect opposite points Bilinear grid theorem: each coordinate line intersects each line of the crossing coordinate line family. The grid is regular in each direction. Bilinear grids

9. Third order convergence of shallow water model at day 3

11. END