Domain & resolution
First you should decide upon the final(!) (see "Cascading" below) domain and resolution you want to run. For this it is important to know that:
- the more grid points a grid has => the more cores are needed
- the higher the resolution => the shorter the model timestep => the longer the runtime of the simulation
Have a look at the following wiki about how to set up a model grid: Set up a model grid
Number of points
Topology (MPI & OpenMP)
Resolution → timestep
The relation between the horizontal resolution and the model timestep is linear. Here are some examples:
| Resolution [degree] | Resolution [km] | model timestep [sec] | For GY grid |
|---|
| 0.009° | ~1 km | 30 s |
|
| 0.0225° | ~2.5 km | 60 s |
|
| 0.036° | ~4 km | 90 s |
|
| 0.11° | ~12 km | 300 s |
|
| ~25 km | 720 s | Grd_nj = 417
|
| ~55 km | 1800 s | Grd_nj = 171
|
Resolution → timestep → radiation timestep
Resolution → (non) hydrostatic
Model levels
LAM grid → top piloting or sponge
Global grid → adjust global pressure
Cascadeing
Spectral nudging
Period
Greenhouse gases
Initial conditions
Driving data
Geophysical fields
Schemes
Land surface scheme (ISBA, CLASS, SVS)
Lake scheme (non, FLake, CSLM)
Urbain scheme (non, TEB)
Radiation
Roughness length
Limit ice /snow
Gravity wave drag
Emissivity
Condensation
Convection
Tracers to advect
Precipitation (Bourgouin)
Boundary layer
Horizontal diffusion
Output fields
Output fields
Instantaneous / averages / min / max
Initial condition fields
Pilot fields (2-D / 3-D)
Output frequency
Output levels
Size of output files (monthly/daily/hourly/...)