CF standard names used by PISM

Existing standard names

We start by listing standard names from the CF Standard Name Table. The subset here is a small subset of the table; we list only

  • those with “land_ice” in the name and
  • those currently used by PISM

The existing names starting with “land_ice” are believed to have all been submitted by Magnus Hagdorn to the CF committee circa 2003. The SeaRISE assessment process now has a wiki on CF standard name use, which to a significant extent duplicates content regarding proposed names on this page. That wiki is an evolving community standard, and it supercedes this page when it comes to actual evolving standards.

Go to the CF Conventions page for the list of proposed standard names under consideration.

Because of the use of UDUNITS, PISM input files do not have to have fields already in the canonical units. Rather, the units attribute has to be valid for UDUNITS conversion into the canonical units. Generally within PISM, the canonical units are used internally.

Table 44 CF standard names used by PISM
CF standard name Canonical units (SI)
bedrock_altitude m
floating_ice_sheet_area_fraction 1
grounded_ice_sheet_area_fraction 1
land_ice_area_fraction 1
land_ice_basal_melt_rate m s-1
land_ice_basal_temperature K
land_ice_basal_upward_velocity m s-1
land_ice_basal_x_velocity m s-1
land_ice_basal_y_velocity m s-1
land_ice_calving_rate m s-1
land_ice_lwe_basal_melt_rate m s-1
land_ice_lwe_calving_rate m s-1
land_ice_lwe_surface_specific_mass_balance m s-1
land_ice_sigma_coordinate 1
land_ice_specific_mass_flux_due_to_calving_and_ice_front_melting kg m-2 s-1
land_ice_surface_specific_mass_balance_flux kg m-2 s-1
land_ice_surface_upward_velocity m s-1
land_ice_surface_x_velocity m s-1
land_ice_surface_y_velocity m s-1
land_ice_temperature K
land_ice_thickness m
land_ice_vertical_mean_x_velocity m s-1
land_ice_vertical_mean_y_velocity m s-1
land_ice_x_velocity m s-1
land_ice_y_velocity m s-1
latitude degree_north
longitude degree_east
magnitude_of_land_ice_basal_drag Pa
projection_x_coordinate m
projection_y_coordinate m
surface_altitude m
temperature_at_ground_level_in_snow_or_firn K
tendency_of_bedrock_altitude m s-1
tendency_of_land_ice_mass_due_to_basal_mass_balance kg s-1
tendency_of_land_ice_thickness m s-1
upward_geothermal_heat_flux_at_ground_level W m-2

Proposed standard names

These are unofficially proposed by Bueler and Aschwanden, for now.

Table 45 Desired CF standard names
Proposed name Canonical units (SI) Comments
ice_shelf_basal_specific_mass_balance m s-1 positive is loss of ice shelf mass (i.e. use outward normal from ice shelf)
ice_shelf_basal_temperature K absolute (not pressure-adjusted) temperature
land_ice_age s  
land_ice_basal_frictional_heating W m-2  
land_ice_basal_material_yield_stress Pa  
land_ice_basal_material_friction_angle degree majority of standard names with “angle” use canonical units “degree”
land_ice_surface_temperature_below_firn K  
land_ice_upward_velocity m s-1 compare to CF names “upward_air_velocity” and “upward_sea_water_velocity”
lithosphere_temperature K  
upward_geothermal_flux_in_lithosphere W m-2 typically applied at depth in lithosphere; compare to “upward_geothermal_heat_flux_at_ground_level”
land_ice_specific_enthalpy J kg-1 enthalpy is defined in PISM to be sensible plus latent heat, plus potential energy of pressure; there is a nontrivial issue of the scaling; the enthalpy value for 273.15 K (cold) ice at atmospheric pressure is a possible standard
land_ice_liquid_fraction 1 liquid water fraction in ice, a pure number between 0 and 1; a diagnostic function of enthalpy

Final technical notes

  • PISM also uses attributes grid_mapping = "mapping" ; and coordinates = "lat lon"; on output variables that depend on y,x.
  • Because PISM uses UDUNITS, it will write some variables in “glaciological units” instead of the SI units listed above, for instance velocities in m year-1 instead of m s-1. This is allowed under CF. When PISM reads such a field from a NetCDF file, the conversion is handled automatically by UDUNITS.

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