Parameters
Yelmo reads its parameters from a namelist file, given to yelmo_init as filename. The defaults are in input/yelmo_defaults.nml, which declares every parameter together with its default value and a short description. A user parameter file only needs to list the parameters it changes. Unknown parameters stop the model at load time, as do values outside their allowed set or range.
The parameters are organised in groups, one per model component:
| Group | Component | Documentation |
|---|---|---|
&yelmo |
Domain, grid, restart, vertical grid, time stepping | Time stepping |
&ytopo |
Topography, mass conservation, front | Mass conservation |
&ycalv |
Calving | Calving |
&ydyn |
Momentum balance, basal friction | Momentum balance, Basal friction |
&ytill |
Till properties (cb_ref) |
Basal friction |
&ymat |
Rheology, enhancement | Thermodynamics |
&ytrc |
Passive tracers (deposition time) | |
&ytherm |
Thermodynamics, bedrock | Thermodynamics |
&yhyd |
Basal hydrology (FastHydrology) | Basal friction |
&yelmo_masks, &yelmo_init_topo, &yelmo_data |
Input files for masks, initial topography and comparison data |
Each group can be renamed in &yelmo (e.g. nml_ydyn = "ydyn_north" reads the dynamics parameters from &ydyn_north), so that several Yelmo domains can share one parameter file. Physical constants are read from input/yelmo_phys_const.nml, in the group given by yelmo.phys_const (default "Earth"; groups for the benchmark experiments, e.g. "EISMINT", "MISMIP3D", are also available).
Groups used only by a driver program, such as &ctrl, are not read by Yelmo.
Masks
&yelmo_masks makes Yelmo’s masks once at init from the regions, zones and basins of FesmData (fesm-utils regions), with selection expressions such as "region:Greenland & ~zone:open_ocean":
| Key | Meaning |
|---|---|
regions_group |
Group of the regions (path_regions, path_basins, basin_sets, layers, masks, …; see fesm-utils regions); "None" = no layers |
basins |
Basin ids of bnd%basins: a layer of the regions, e.g. "<set>" or "<set>.group" ("Zwally2012.group"); "None" = none, "domain" = one basin (1) |
mask_ice_dynamic |
Where ice is dynamic; elsewhere no ice (bnd%mask_ice) |
mask_ice_fixed |
Where ice thickness is prescribed (over mask_ice_dynamic) |
relax, relax_tau |
Where ice relaxes to H_ice_ref and the timescale [yr] (bnd%tau_relax, used with ytopo.topo_rel = -1) |
mask_rmse |
Where the error metrics are computed |
dynamic_connected |
Keep only the dynamic cells connected to the ice sheet (the largest 4-connected region of present-day ice, else of the initial ice) through dynamic or fixed cells; the others get no ice (e.g. offshore islands) |
Without layers the expressions can only be "all" or "none". A driver may pass the regions (yelmo_init(..., reg=), on the Yelmo grid) instead of regions_group, and mask_ice instead of the mask_ice expressions. The named masks of the regions (masks, mask_<name>) become Yelmo’s regional output domains. bnd%regions holds the codes of the layer region (FesmData: the deepest level), 0 without one.
To browse, build, compare and validate parameter files from the command line, see yelmo-config.