Effect of Hydrostatic and Non-Hydrostatic Modes in High Resolution Model

Abstract. The study is based on using an alternative approach to designa non-hydrostatic numerical weather prediction (NWP) model.The main idea of this approach is to split the system of nonhydrostaticequation into two parts, one corresponds to the hydrostaticsystem while the second one (non-hydrostatic system) is the system ofequations that allows computation of the corrections appearing in thefirst system due to the vertical acceleration. With this approach, thenon-hydrostatic model is considered as an extension of a hydrostaticmodel by adding the subroutines, calculating the vertical accelerationand its contribution and the correction results in the pressure gradientterms and ωα-term in the thermodynamic equation. In this study, onedirection nest from the non-hydrostatic mode on resolution 1/3 lat x lon, has been tested for the two modes (hydrostatic and nonhydrostatic),first for resolution about 18 x18 km and second for resolution10 x10 km. The result of the first resolution does not give significancebetween the two modes, but the second resolution, when the resolution was nearest the non-hydrostatic scale feature, some significantdifference appears between the two modes, especially in the rainfall areas.