Nonhydrostatic atmospheric Modeling using a z-coordinate representation

A representation of the orography based on approximate finite-volume techniques is applied to a nonhydrostatic atmospheric model. Techniques previously developed by the authors in the context of a semi-implicit, semi-Lagrangian model are applied also to a Eulerian, split-explicit model. Furthermore, an improved formulation of the original approach is introduced, which allows for better orography representation by introducing a simplified version of the most general shaved cells. A two-dimensional numerical test shows that the method developed does not suffer from the problems reported in connection with the eta-coordinate.