|
WRF (v3.9.1) |
MPAS-A (v6.3) |
CPAS  |
Model type |
  Limited-area model, targeting for high-resolution simulation within the domain. |
  Global model with moderate regional resolution refinement. |
  Global model with arbitrary resolution refinement, including extreme resolution refinement for small region. |
Forecast accuracy and time horizon |
  Very accurate within the high-resolution region up to about 3 days. |
  Generally accurate for medium-range time horizon up to about 9 days. |
  Very accurate within the high-resolution region and generally accurate for medium-range time horizon, up to about 9 days with an appropriately designed mesh. |
Time stepping |
  Each domain uses its own time step size specified in WRF namelist. |
  All cells in the globe uses the same time step size disregarding cell size variation.
(This time step size is limited by the smallest cell in the entire mesh. This is required to meet the stability condition for time integration. The presence of a small cell in the mesh makes the computational resource requirement prohibitively large. )
|
  Mesh cells of different sizes use different timesteps.
(This not only reduces the required computational resources, but also enables the use of extreme variable resolution on a global mesh.)
|
Hierarchical time-stepping (HTS) report |
  N/A |
  N/A |
  Available after mesh generation, showing regions of time stepping levels and resource utilization. |
Parallelization and load balancing |
  The computation of each domain is parallelized while the execution sequence of nested domains is serial. |
  The mesh of the whole globe is fully partitioned and the parallelization is excellent. |
  The mesh of the whole globe is fully partitioned with consideration of time-stepping. |
Scalability |
  Scalability limited by the domain with smallest number of grid cells. |
  Extremely scalable. |
  Extremely scalable. |
Scale-awareness of physics model |
  Different domains may use different physics models. |
  No scale-awareness in convection scheme except Grell-Freitas scheme. |
  Automatically switch off cumulus parameterization for small cells. |
Handling wave reflection in resolution jump / transition. |
  Handled by specified zone and relaxation zone near lateral boundaries for the resolution jump. |
  Handled by filtering, with default / specified coefficients for horizontal diffusion, for gradual resolution transition. |
  The mesh generation algorithm creates customized mesh with smooth resolution transition that can be handled by filtering with default coefficients for horizontal diffusion. |
Model inconsistency between regional and the global driving model |
  Different parameterization in physics models, especially those related to moisture, between WRF and the driving global model results in artifacts and spurious effects propagating from the lateral boundaries into the region of interest. |
  No such problem. |
  No such problem. |