SCALE-DG is a three-dimensional (3D) regional and global atmospheric model in which both of the horizontal and the vertical discretizations are based on the discontinuous Galerkin (DG) method.

Brief Description

Features

  • Support both 3D regional and global simulations only in SCALE-DG
    • This feature is provided by a model framework provided by our DG library
  • Execute parallel simulations in supercomputers
    • Process and thread parallelizations are performed by MPI library (we use 2D domain compositions) and OpenMP, respectively.
  • Generate initial data for idealized experiments
  • Treat NetCDF files as input and output data

Dynamical core

  • Governing equation: 3D fully compressible non-hydrostatic equations
  • Grid system: hexahedral finite element and horizontally curvilinear coordinate system
    • for the global mode, cubed sphere coordinate is specifically adopted.
    • Topography can be treated using a terrain-following coordinate
  • Spatial discretization: nodal discontinuous Galerkin method (e.g., Hesthave and Warburton, 2007)
    • Polynomial order associated with numerical accuracy can be arbitrarily chosen.
    • Numerical flux: Rusanov flux
    • Stabilization mechanisms: numerical diffusion with numerical flux, modal filtering
  • Temporal discretization: various type of Runge-Kutta (RK) schemes
    • full explicit (horizontally and vertically explicit; HEVE)
      • classical 4s4o RK scheme (where 4s4o means 4th-order and 4 stage)
      • strong-stability preserving (SSP) RK schemes: 3s3o, 4s3o, 5s3o (Higueras and Roldan, 2018), 10s4o (Ketcheson, 2008)
    • horizontally explicit and vertically implicit (HEVI)
      • implicit and explicit RK schemes: ARK232 (Giraldo et al., 2013), ARK324 (Kennedy and Carpenter, 2003)
  • Tracer transport
    • Preserving the non-negativity is ensured by a limiter (Light and Durran, 2016) and SSP RK schemes in conjunction with fundamental spatial discretization by nodal DGM.

Physical processes

  • Turbulence process
    • Smagorinsky (1963) and Lilly (1962)-type sub-grid scale model corrected by Brown et al. (1994) and Scotti et al. (1993) (available only in regional model)
  • Cloud microphysics (using the SCALE library)
    • 3-class 1 moment bulk scheme (Kessler 1969)

Documents

The description of SCALE-DG is available at Document page.

Example of numerical experiments

Simulation results of standard test cases such as baroclinic wave and Held Suarez experiments are shown in Gallery page.