Introduction to the GRAPES global system

Jiandong Gong
  18 Oct, Noon, in 2554

The Global/Regional Analysis and Prediction System (GRAPES) is an operational numerical weather prediction system developed by China with the supports of the Ministry of Science and Technology and the China Meteorological Administration. By end of 2019, a series of GRAPES sub-systems have been established to follow up the GRAPES_GFS, such as GRAPES_GEPS (global ensemble prediction system), GRAPE_MESO (3km regional system, 10km regional rapid update assimilation system, 10 km regional ensemble prediction system) and GRAPES-Typhoon (the northwest Pacific-Indian Ocean typhoon prediction system).

Recently, there are many upgrades of GRAPES-GFS around dynamics, physics and data assimilation. The upgraded system introduced 1) The three-dimensional reference profile, predictor-corrector semi-implicit semi-Lagrangian (SISL) scheme, high-resolution spectral filtering terrain, which effectively improves the accuracy of the model dynamics; 2) The improved boundary layer scheme and two-moment microphysics scheme under Charney-phillips vertical grid, and the optimization of surface layer to match Charney-phillips vertical grid, the modification of convection scheme which effectively mitigation humidity bias; 3) The improvement from global 3DVar to 4DVar analysis, and the influence of linearization of moisture physical process on the analysis; 4) The tangent linear model and adjoint model developed in 4DVar system which is also applied to the global ensemble prediction system for singular vector initial perturbation.

The verification statistics have demonstrated the improvement of GFS from each upgrade. Meanwhile, increasing the model vertical levels from 60 to 87 and ensemble of 4DVar based En4DVar have been investigated as well. Finally, CMA NWP center's model development plan (out to 2025) will be presented.