GRAPES (a short form of Global/Regional Assimilation and PrEdiction System) is a new generation of multi-scale numerical prediction system developed by China Meteorological Administration (CMA).
In the GRAPES model, the atmosphere is assumed shallow, fully compressible and non-hydrostatical. A height-based-terrain following coordinate, which was proposed by Chen and Somerville, was used in the GRAPES model. A profile of “hydrostatic atmosphere” is introduced as reference for eliminating the hydrostatical components of the vertical motion equation. The semi-implicit and semi-Lagrangian (SI-SL) integration scheme was used, and a longitude-latitude grid spherical system was used for horizontal discretization. The GRAPES model uses the Charney-Philips scheme for the vertically staggered variable arrangement, and the Arakawa-C grid for the horizontally staggered variable arrangement.
The physical schemes of GRAPES include cumulus convection, micro-physics, long and short-waves radiation, planet boundary layer processes, and earth surface processes.