TOWARD CONVECTIVE-SCALE PREDICTION WITHIN THE NEXT GENERATION GLOBAL PREDICTION SYSTEM

• Published in: Bulletin of the American Meteorological Society Vol. 100; no. 7; pp. 1225 - 1244
• Main Authors: Zhou, Linjiong, Lin, Shian-Jiann, Chen, Jan-Huey, Harris, Lucas M., Chen, Xi, Rees, Shannon L.
• Format: Journal Article
• Language: English
• Published: Boston American Meteorological Society 01.07.2019
• Subjects: Boundary conditions; Cloud microphysics; Computational fluid dynamics; Computer simulation; Convection; Data assimilation; Diurnal; Diurnal cycle; Diurnal variations; Energy conservation; Extreme weather; Finite element method; Fluid dynamics; Geophysical fluids; Geophysics; Hurricanes; Hydrodynamics; Laboratories; Mathematical models; Mesoscale phenomena; Microphysics; Plains; Precipitation; Prototypes; Resolution; Squalls; Statistical methods; Weather forecasting; United States > US; New Jersey
• ISSN: 0003-0007; 1520-0477
• DOI: 10.1175/bams-d-17-0246.1

The Geophysical Fluid Dynamics Laboratory (GFDL) has developed a new variable-resolution global model with the ability to represent convective-scale features that serves as a prototype of the Next Generation Global Prediction System (NGGPS). The goal of this prediction system is to maintain the skill in large-scale features while simultaneously improving the prediction skill of convectively driven mesoscale phenomena. This paper demonstrates the new capability of this model in convective-scale prediction relative to the current operational Global Forecast System (GFS). This model uses the stretched-grid functionality of the Finite-Volume Cubed-Sphere Dynamical Core (FV3) to refine the global 13-km uniform-resolution model down to 4-km convection-permitting resolution over the contiguous United States (CONUS), and implements the GFDL single-moment 6-category cloud microphysics to improve the representation of moist processes. Statistics gathered from two years of simulations by the GFS and select configurations of the FV3-based model are carefully examined. The variable-resolution FV3-based model is shown to possess global forecast skill comparable with that of the operational GFS while quantitatively improving skill and better representing the diurnal cycle within the high-resolution area compared to the uniform mesh simulations. Forecasts of the occurrence of extreme precipitation rates over the southern Great Plains are also shown to improve with the variable-resolution model. Case studies are provided of a squall line and a hurricane to demonstrate the effectiveness of the variable-resolution model to simulate convective-scale phenomena.