Effect of hydrostatic and non-hydrostatic modes in high resolution model

Abstract EN

The study is based on using an alternative approach to de-sign a non-hydrostatic numerical weather prediction (NWP) model.

The main idea of this approach is to split the system of non-hydrostatic equation into two parts, one corresponds to the hydrostatic system while the second one (non-hydrostatic system) is the system of equations that allows computation of the corrections appearing in the first system due to the vertical acceleration.

With this approach, the non-hydrostatic model is considered as an extension of a hydrostatic model by adding the subroutines, calculating the vertical acceleration and its contribution and the correction results in the pressure gradient terms and ωα-term in the thermodynamic equation.

In this study, one direction nest from the non-hydrostatic mode on resolution 1⁄3 lat × lon, has been tested for the two modes (hydrostatic and non-hydrostatic), first for resolution about 18 × 18 km and second for reso-lution 10 × 10 km.

The result of the first resolution does not give sig-nificance between the two modes, but the second resolution, when the resolution was nearest the non-hydrostatic scale feature, some signifi-cant difference appears between the two modes, especially in the rain-fall areas.