Configuration parameters¶

Every parameter corresponds to a command-line option; some options map to a combination of parameters.

There are five kinds of options and parameters:

Strings (mostly file names),
Scalars (a number representing a physical quantify, usually with units),
Integers (an integer number, usually corresponding to a count),
Flags (True/False, on/off, yes/no),
Keywords (one of a given set of strings).

Each parameter can be set using the command-line option consisting of a dash followed by the parameter name. For example,

-constants.standard_gravity 10

sets the acceleration due to gravity (parameter constants.standard_gravity) to \(10\). Options listed below are shortcuts, added for convenience.

The following are equivalent and choose the temperature-based (as opposed to enthalpy-based) energy balance model:

-energy.temperature_based
-energy.temperature_based on
-energy.temperature_based yes
-energy.temperature_based true
-energy.temperature_based True

The following are also equivalent: they disable updating geometry by performing a step of the mass-continuity equation:

-geometry.update.enabled off
-geometry.update.enabled no
-geometry.update.enabled false
-geometry.update.enabled False
-no_geometry.update.enabled

The -no_ prefix is still supported for compatibility with older scripts, but will be removed in a later PISM version.

age.enabled

Solve age equation (advection equation for ice age).

Type

flag

Default value

no

Option

-age
age.initial_value

Initial age of ice

Type

number

Default value

0 (years)
atmosphere.anomaly.file

Name of the file containing climate forcing fields.

Type

string

Default value

empty

Option

-atmosphere_anomaly_file
atmosphere.anomaly.periodic

If true, interpret forcing data as periodic in time

Type

flag

Default value

no
atmosphere.delta_P.file

Name of the file containing scalar precipitation offsets.

Type

string

Default value

empty

Option

-atmosphere_delta_P_file
atmosphere.delta_P.periodic

If true, interpret forcing data as periodic in time

Type

flag

Default value

no
atmosphere.delta_T.file

Name of the file containing temperature offsets.

Type

string

Default value

empty

Option

-atmosphere_delta_T_file
atmosphere.delta_T.periodic

If true, interpret forcing data as periodic in time

Type

flag

Default value

no
atmosphere.elevation_change.file

Name of the file containing the reference surface elevation field (variable usurf).

Type

string

Default value

empty

Option

-atmosphere_lapse_rate_file
atmosphere.elevation_change.periodic

If true, interpret forcing data as periodic in time

Type

flag

Default value

no
atmosphere.elevation_change.precipitation.lapse_rate

Elevation lapse rate for the precipitation

Type

number

Default value

0 ((kg m-2 / year) / km)

Option

-precip_lapse_rate
atmosphere.elevation_change.precipitation.method

Choose the precipitation adjustment method. scale: use temperature-change-dependent scaling factor. shift: use the precipitation lapse rate.

Type

keyword

Default value

shift

Choices

scale, shift

Option

-precip_adjustment
atmosphere.elevation_change.precipitation.temp_lapse_rate

Elevation lapse rate for the surface temperature used to compute \(\Delta T\) in the precipitation scaling factor \(\exp(C \cdot \Delta T)\)

Type

number

Default value

0 (Kelvin / km)

Option

-precip_temp_lapse_rate
atmosphere.elevation_change.temperature_lapse_rate

Elevation lapse rate for the surface temperature

Type

number

Default value

0 (Kelvin / km)

Option

-temp_lapse_rate
atmosphere.fausto_air_temp.c_ma

latitude-dependence coefficient for formula (1) in [1]

Type

number

Default value

-0.7189 (Kelvin / degree_north)
atmosphere.fausto_air_temp.c_mj

latitude-dependence coefficient for formula (2) in [1]

Type

number

Default value

-0.1585 (Kelvin / degree_north)
atmosphere.fausto_air_temp.d_ma

41.83+273.15; base temperature for formula (1) in [1]

Type

number

Default value

314.98 (Kelvin)
atmosphere.fausto_air_temp.d_mj

= 14.70+273.15; base temperature for formula (2) in [1]

Type

number

Default value

287.85 (Kelvin)
atmosphere.fausto_air_temp.gamma_ma

= -6.309 / 1km; mean slope lapse rate for formula (1) in [1]

Type

number

Default value

-0.006309 (Kelvin / meter)
atmosphere.fausto_air_temp.gamma_mj

= -5.426 / 1km; mean slope lapse rate for formula (2) in [1]

Type

number

Default value

-0.005426 (Kelvin / meter)
atmosphere.fausto_air_temp.kappa_ma

longitude-dependence coefficient for formula (1) in [1]

Type

number

Default value

0.0672 (Kelvin / degree_west)
atmosphere.fausto_air_temp.kappa_mj

longitude-dependence coefficient for formula (2) in [1]

Type

number

Default value

0.0518 (Kelvin / degree_west)
atmosphere.fausto_air_temp.summer_peak_day

day of year for July 15; used in corrected formula (4) in [1]

Type

integer

Default value

196 (ordinal day number)
atmosphere.frac_P.file

Name of the file containing scalar precipitation scaling.

Type

string

Default value

empty

Option

-atmosphere_frac_P_file
atmosphere.frac_P.periodic

If true, interpret forcing data as periodic in time

Type

flag

Default value

no
atmosphere.given.file

Name of the file containing climate forcing fields.

Type

string

Default value

empty

Option

-atmosphere_given_file
atmosphere.given.periodic

If true, interpret forcing data as periodic in time

Type

flag

Default value

no
atmosphere.models

Comma-separated list of atmosphere melt models and modifiers.

Type

string

Default value

given

Option

-atmosphere
atmosphere.one_station.file

Specifies a file containing scalar time-series precipitation and air_temp.

Type

string

Default value

empty

Option

-atmosphere_one_station_file
atmosphere.orographic_precipitation.background_precip_post

Background precipitation \(P_{\mathrm{post}}\) added after the truncation.

Type

number

Default value

0 (mm/hr)

Option

-background_precip_post
atmosphere.orographic_precipitation.background_precip_pre

Background precipitation \(P_{\mathrm{pre}}\) added before the truncation.

Type

number

Default value

0 (mm/hr)

Option

-background_precip_pre
atmosphere.orographic_precipitation.conversion_time

Cloud conversion time \(\tau_c\)

Type

number

Default value

1000 (s)

Option

-conversion_time
atmosphere.orographic_precipitation.coriolis_latitude

Latitude used to compute Coriolis force

Type

number

Default value

0 (degrees_N)

Option

-coriolis_latitude
atmosphere.orographic_precipitation.fallout_time

Fallout time \(\tau_f\)

Type

number

Default value

1000 (s)

Option

-fallout_time
atmosphere.orographic_precipitation.grid_size_factor

The size of the extended grid is (Z*(grid.Mx - 1) + 1, Z*(grid.My - 1) + 1) where Z is given by this parameter.

Type

integer

Default value

2 (count)
atmosphere.orographic_precipitation.lapse_rate

Lapse rate \(\gamma\)

Type

number

Default value

-5.8 (K / km)

Option

-lapse_rate
atmosphere.orographic_precipitation.moist_adiabatic_lapse_rate

Moist adiabatic lapse rate \(\Gamma_m\)

Type

number

Default value

-6.5 (K / km)

Option

-moist_adiabatic_lapse_rate
atmosphere.orographic_precipitation.moist_stability_frequency

Moist stability frequency \(N_m\)

Type

number

Default value

0.05 (1/s)

Option

-moist_stability_frequency
atmosphere.orographic_precipitation.reference_density

Reference density \(\rho_{S_{\text{ref}}}\)

Type

number

Default value

0.0074 (kg m-3)

Option

-reference_density
atmosphere.orographic_precipitation.scale_factor

Precipitation scaling factor \(S\).

Type

number

Default value

1 (1)

Option

-scale_factor
atmosphere.orographic_precipitation.smoothing_standard_deviation

Standard deviation of the Gaussian filter used to smooth surface elevation or zero if disabled

Type

number

Default value

0 (m)
atmosphere.orographic_precipitation.truncate

Truncate precipitation at 0, disallowing negative precipitation values.

Type

flag

Default value

true

Option

-truncate
atmosphere.orographic_precipitation.water_vapor_scale_height

Water vapor scale height \(H_w\)

Type

number

Default value

2500 (m)

Option

-water_vapor_scale_height
atmosphere.orographic_precipitation.wind_direction

The direction the wind is coming from

Type

number

Default value

270 (degrees)

Option

-wind_direction
atmosphere.orographic_precipitation.wind_speed

The wind speed.

Type

number

Default value

10 (m/s)

Option

-wind_speed
atmosphere.pik.file

Name of the file containing the reference surface elevation field (variable usurf).

Type

string

Default value

empty

Option

-atmosphere_pik_file
atmosphere.pik.parameterization

Selects parameterizations of mean annual and mean summer near-surface air temperatures.

Type

keyword

Default value

martin

Choices

martin, huybrechts_dewolde, martin_huybrechts_dewolde, era_interim, era_interim_sin, era_interim_lon

Option

-atmosphere_pik
atmosphere.precip_exponential_factor_for_temperature

= 0.169/2.4; in SeaRISE-Greenland formula for precipitation correction using air temperature offsets relative to present; a 7.3% change of precipitation rate for every one degC of temperature change [2]

Type

number

Default value

0.0704167 (Kelvin-1)
atmosphere.precip_scaling.file

Name of the file containing temperature offsets to use for a precipitation correction.

Type

string

Default value

empty

Option

-atmosphere_precip_scaling_file
atmosphere.precip_scaling.periodic

If true, interpret forcing data as periodic in time

Type

flag

Default value

no
atmosphere.searise_greenland.file

Name of the file containing a precipitation field.

Type

string

Default value

empty

Option

-atmosphere_searise_greenland_file
atmosphere.uniform.precipitation

Precipitation used by the uniform atmosphere model.

Type

number

Default value

1000 (kg m-2 year-1)
atmosphere.uniform.temperature

Air temperature used by the uniform atmosphere model.

Type

number

Default value

273.15 (Kelvin)
atmosphere.yearly_cycle.file

Name of the file containing mean annual and mean July temperatures (air_temp_mean_annual and air_temp_mean_summer) and the precipitation field.

Type

string

Default value

empty

Option

-atmosphere_yearly_cycle_file
atmosphere.yearly_cycle.scaling.file

Name of the file containing amplitude scaling (amplitude_scaling) for the near-surface air temperature.

Type

string

Default value

empty

Option

-atmosphere_yearly_cycle_scaling_file
atmosphere.yearly_cycle.scaling.periodic

If true, interpret forcing data as periodic in time

Type

flag

Default value

no
basal_resistance.beta_ice_free_bedrock

value is for ice stream E from [117]; thus sliding velocity, but we hope it doesn’t matter much; at 100 m/year the linear sliding law gives 57040 Pa basal shear stress

Type

number

Default value

1.8e+09 (Pascal second meter-1)
basal_resistance.beta_lateral_margin

high value of \(\beta\) used to simulate drag at lateral ice margins (fjord walls, etc); the default value is chosen to disable flow in the direction along a margin

Type

number

Default value

1e+19 (Pascal second meter-1)
basal_resistance.plastic.regularization

Set the value of \(\epsilon\) regularization of plastic till; this is the second \(\epsilon\) in formula (4.1) in [45]

Type

number

Default value

0.01 (meter / year)

Option

-plastic_reg
basal_resistance.pseudo_plastic.enabled

Use the pseudo-plastic till model (basal sliding law).

Type

flag

Default value

no

Option

-pseudo_plastic
basal_resistance.pseudo_plastic.q

The exponent of the pseudo-plastic basal resistance model

Type

number

Default value

0.25 (pure number)

Option

-pseudo_plastic_q
basal_resistance.pseudo_plastic.sliding_scale_factor

divides pseudo-plastic tauc (yield stress) by given factor; this would increase sliding by given factor in absence of membrane stresses; not used if negative or zero; not used by default

Type

number

Default value

-1 (1)

Option

-sliding_scale_factor_reduces_tauc
basal_resistance.pseudo_plastic.u_threshold

threshold velocity of the pseudo-plastic sliding law

Type

number

Default value

100 (meter / year)

Option

-pseudo_plastic_uthreshold
basal_resistance.regularized_coulomb.enabled

Use the regularized Coulomb till friction model (basal sliding law) as in equation (3) in [106]

Type

flag

Default value

no

Option

-regularized_coulomb
basal_yield_stress.add_transportable_water

If “yes” then the water amount in the transport system is added to tillwat in determining tauc (in the Mohr-Coulomb relation). Normally only the water in the till is used.

Type

flag

Default value

no

Option

-tauc_add_transportable_water
basal_yield_stress.constant.value

fill value for yield stress for basal till (plastic or pseudo-plastic model); note \(2 \times 10^5\) Pa = 2 bar is quite strong and little sliding should occur

Type

number

Default value

200000 (Pascal)

Option

-tauc
basal_yield_stress.ice_free_bedrock

the “high” yield stress value used in grounded ice-free areas.

Type

number

Default value

1e+06 (Pascal)

Option

-high_tauc
basal_yield_stress.model

The basal yield stress model to use when sliding is active.

Type

keyword

Default value

mohr_coulomb

Choices

constant, mohr_coulomb, tillphi_opt

Option

-yield_stress
basal_yield_stress.mohr_coulomb.delta.file

Name of the file containing space- and time-dependent variable mohr_coulomb_delta to use instead of basal_yield_stress.mohr_coulomb.till_effective_fraction_overburden.

Type

string

Default value

empty

Option

-mohr_coulomb_delta_file
basal_yield_stress.mohr_coulomb.delta.periodic

If true, interpret forcing data as periodic in time

Type

flag

Default value

no
basal_yield_stress.mohr_coulomb.tauc_to_phi.file

File containing the basal yield stress field that should be used to recover the till friction angle distribution.

Type

string

Default value

empty

Option

-tauc_to_phi
basal_yield_stress.mohr_coulomb.till_cohesion

cohesion of till; = \(c_0\) in most references; note Schoof uses zero but Paterson pp 168–169 gives range 0–40 kPa; but Paterson notes that “… all the pairs \(c_0\) and \(\phi\) in the table would give a yield stress for Ice Stream B that exceeds the basal shear stress there…”

Type

number

Default value

0 (Pascal)

Option

-till_cohesion
basal_yield_stress.mohr_coulomb.till_compressibility_coefficient

coefficient of compressiblity of till; value from [109]

Type

number

Default value

0.12 (pure number)

Option

-till_compressibility_coefficient
basal_yield_stress.mohr_coulomb.till_effective_fraction_overburden

\(\delta\) in [110]; \(\delta P_o \le N_{\text{till}} \le P_o\) where \(P_o\) is overburden pressure and \(N_{\text{till}}\) is the effective pressure of the overlying ice on the saturated till; default value of \(\delta\) corresponds to Greenland and Antarctic model runs

Type

number

Default value

0.02 (pure number)

Option

-till_effective_fraction_overburden
basal_yield_stress.mohr_coulomb.till_log_factor_transportable_water

If basal_yield_stress.add_transportable_water is set then the water amount in the transport system is added to tillwat in determining tauc. Normally only the water in the till is used. This factor multiplies the logarithm in that formula.

Type

number

Default value

0.1 (meters)

Option

-till_log_factor_transportable_water
basal_yield_stress.mohr_coulomb.till_phi_default

fill value for till friction angle

Type

number

Default value

30 (degrees)

Option

-plastic_phi
basal_yield_stress.mohr_coulomb.till_reference_effective_pressure

reference effective pressure \(N_0\); value from [109]

Type

number

Default value

1000 (Pascal)
basal_yield_stress.mohr_coulomb.till_reference_void_ratio

void ratio at reference effective pressure \(N_0\); value from [109]

Type

number

Default value

0.69 (pure number)

Option

-till_reference_void_ratio
basal_yield_stress.mohr_coulomb.tillphi_opt.dhdt_min

rate of change in the surface elevation mismatch \(D\) used as a convergence criterion

Type

number

Default value

0.001 (meters year-1)

Option

-tillphi_opt_dhdt_min
basal_yield_stress.mohr_coulomb.tillphi_opt.dphi_max

maximum till friction angle adjustment \(\dphimax\)

Type

number

Default value

1 (degrees)

Option

-tillphi_opt_dphi_max
basal_yield_stress.mohr_coulomb.tillphi_opt.dphi_scale

scaling factor \(C\) used to compute the \(\Delta \phi\) adjustment, \(C\) degrees per meter of surface elevation mismatch

Type

number

Default value

0.002 (degree / meters)

Option

-tillphi_opt_dphi_scale
basal_yield_stress.mohr_coulomb.tillphi_opt.dt

time step \(\dt_{\phi}\) for optimization of till friction angle

Type

number

Default value

250 (365days)

Option

-tillphi_opt_dt
basal_yield_stress.mohr_coulomb.tillphi_opt.file

Name of the file containing the time-independent variable usurf used as target surface elevation

Type

string

Default value

empty

Option

-tillphi_opt_file
basal_yield_stress.mohr_coulomb.tillphi_opt.phi0_max

maximum value of the lower bound of the till friction angle, \(\phi_{0,\mathrm{max}}\)

Type

number

Default value

5 (degrees)

Option

-tillphi_opt_phi0_max
basal_yield_stress.mohr_coulomb.tillphi_opt.phi0_min

minimum value of the lower bound of the till friction angle, \(\phi_{0,\mathrm{min}}\)

Type

number

Default value

2 (degrees)

Option

-tillphi_opt_phi0_min
basal_yield_stress.mohr_coulomb.tillphi_opt.phi_max

upper bound of the till friction angle \(\phimax\)

Type

number

Default value

70 (degrees)

Option

-tillphi_opt_phi_max
basal_yield_stress.mohr_coulomb.tillphi_opt.topg_max

the bed elevation \(\bmax\) above which basal_yield_stress.mohr_coulomb.tillphi_opt.phi0_max is used

Type

number

Default value

700 (meters)

Option

-tillphi_opt_topg_max
basal_yield_stress.mohr_coulomb.tillphi_opt.topg_min

the bed elevation \(\bmin\) below which basal_yield_stress.mohr_coulomb.tillphi_opt.phi0_min is used

Type

number

Default value

-300 (meters)

Option

-tillphi_opt_topg_min
basal_yield_stress.mohr_coulomb.topg_to_phi.enabled

If the option -topg_to_phi is set then this will be set to “yes”, and then MohrCoulombYieldStress will initialize the tillphi field using a piece-wise linear function of depth described by four parameters.

Type

flag

Default value

no
basal_yield_stress.mohr_coulomb.topg_to_phi.phi_max

upper value of the till friction angle; see the implementation of MohrCoulombYieldStress

Type

number

Default value

15 (degrees)
basal_yield_stress.mohr_coulomb.topg_to_phi.phi_min

lower value of the till friction angle; see the implementation of MohrCoulombYieldStress

Type

number

Default value

5 (degrees)
basal_yield_stress.mohr_coulomb.topg_to_phi.topg_max

the elevation at which the upper value of the till friction angle is used; see the implementation of MohrCoulombYieldStress

Type

number

Default value

1000 (meters)
basal_yield_stress.mohr_coulomb.topg_to_phi.topg_min

the elevation at which the lower value of the till friction angle is used; see the implementation of MohrCoulombYieldStress

Type

number

Default value

-1000 (meters)
basal_yield_stress.slippery_grounding_lines

If yes, at icy grounded locations with bed elevations below sea level, within one cell of floating ice or ice-free ocean, make tauc as low as possible from the Mohr-Coulomb relation. Specifically, at such locations replace the normally-computed tauc from the Mohr-Coulomb relation, which uses the effective pressure from the modeled amount of water in the till, by the minimum value of tauc from Mohr-Coulomb, i.e. by using the effective pressure corresponding to the maximum amount of till-stored water. Does not alter the modeled or reported amount of till water, nor does this mechanism affect water conservation.

Type

flag

Default value

no

Option

-tauc_slippery_grounding_lines
bed_deformation.bed_topography_delta_file

The name of the file to read the topg_delta from. This field is added to the bed topography during initialization.

Type

string

Default value

empty

Option

-topg_delta_file
bed_deformation.bed_uplift_file

The name of the file to read the uplift (dbdt) from. Leave empty to read it from an input file or a regridding file.

Type

string

Default value

empty

Option

-uplift_file
bed_deformation.given.file

Name of the file containing time-dependent topg_delta.

Type

string

Default value

empty

Option

-topg_delta_file
bed_deformation.given.reference_file

Name of the file containing the reference bed topography topg.

Type

string

Default value

empty

Option

-topg_reference_file
bed_deformation.lc.elastic_model

Use the elastic part of the Lingle-Clark bed deformation model.

Type

flag

Default value

yes

Option

-bed_def_lc_elastic_model
bed_deformation.lc.grid_size_factor

The spectral grid size is (Z*(grid.Mx - 1) + 1, Z*(grid.My - 1) + 1) where Z is given by this parameter. See [112], [27].

Type

integer

Default value

4 (count)
bed_deformation.lc.update_interval

Interval between updates of the Lingle-Clark model

Type

number

Default value

10 (365days)
bed_deformation.lithosphere_flexural_rigidity

lithosphere flexural rigidity used by the bed deformation model. See [112], [27]

Type

number

Default value

5e+24 (Newton meter)
bed_deformation.mantle_density

half-space (mantle) density used by the bed deformation model. See [112], [27]

Type

number

Default value

3300 (kg meter-3)
bed_deformation.mantle_viscosity

half-space (mantle) viscosity used by the bed deformation model. See [112], [27]

Type

number

Default value

1e+21 (Pascal second)
bed_deformation.model

Selects a bed deformation model to use. iso is point-wise isostasy, lc is the Lingle-Clark model (see [112], requires FFTW), given uses prescribed bed topography changes read from a file.

Type

keyword

Default value

none

Choices

none, iso, lc, given

Option

-bed_def
bootstrapping.defaults.bed

bed elevation value to use if topg (bedrock_altitude) variable is absent in bootstrapping file

Type

number

Default value

1 (meters)
bootstrapping.defaults.bmelt

basal melt rate value to use if variable bmelt is absent in bootstrapping file

Type

number

Default value

0 (meter / second)
bootstrapping.defaults.bwat

till water thickness value to use if variable tillwat is absent in bootstrapping file

Type

number

Default value

0 (meters)
bootstrapping.defaults.bwp

basal water pressure value to use if variable bwp is absent in bootstrapping file; most hydrology models do not use this value because bwp is diagnostic

Type

number

Default value

0 (Pascal)
bootstrapping.defaults.geothermal_flux

geothermal flux value to use if bheatflx variable is absent in bootstrapping file

Type

number

Default value

0.042 (Watt meter-2)
bootstrapping.defaults.ice_thickness

thickness value to use if thk (land_ice_thickness) variable is absent in bootstrapping file

Type

number

Default value

0 (meters)
bootstrapping.defaults.tillwat

till water thickness value to use if variable tillwat is absent in bootstrapping file

Type

number

Default value

0 (meters)
bootstrapping.defaults.uplift

uplift value to use if dbdt variable is absent in bootstrapping file

Type

number

Default value

0 (meter / second)
bootstrapping.temperature_heuristic

The heuristic to use to initialize ice temperature during bootstrapping: smb uses the surface mass balance, surface temperature, and the geothermal flux, quartic_guess uses the surface temperature and the geothermal flux.

Type

keyword

Default value

smb

Choices

smb, quartic_guess

Option

-boot_temperature_heuristic
calving.eigen_calving.K

Set proportionality constant to determine calving rate from strain rates. Note references [89], [3] use K in range \(10^{9}\) to \(3 \times 10^{11}\) m a, that is, \(3 \times 10^{16}\) to \(10^{19}\) m s.

Type

number

Default value

0 (meter second)

Option

-eigen_calving_K
calving.float_kill.calve_near_grounding_line

Calve floating ice near the grounding line.

Type

flag

Default value

yes

Option

-float_kill_calve_near_grounding_line
calving.float_kill.margin_only

Apply float_kill at ice margin cells only.

Type

flag

Default value

no

Option

-float_kill_margin_only
calving.hayhurst_calving.B_tilde

Effective damage rate [91]

Type

number

Default value

65 ((MPa)^r / year)
calving.hayhurst_calving.exponent_r

Damage law exponent [91]

Type

number

Default value

0.43 (1)
calving.hayhurst_calving.sigma_threshold

Damage threshold stress [91]

Type

number

Default value

0.17 (MPa)
calving.methods

comma-separated list of calving methods; one or more of eigen_calving, float_kill, thickness_calving

Type

string

Default value

empty

Option

-calving
calving.rate_scaling.file

File containing the scaling factor applied to calving rates from eigen_calving, vonmises_calving, and hayhurst_calving (variable name: frac_calving_rate)

Type

string

Default value

empty
calving.rate_scaling.periodic

If true, interpret forcing data as periodic in time

Type

flag

Default value

no
calving.thickness_calving.file

Name of the file containing the spatially-variable thickness calving threshold.

Type

string

Default value

empty

Option

-thickness_calving_file
calving.thickness_calving.periodic

If true, interpret forcing data as periodic in time

Type

flag

Default value

no
calving.thickness_calving.threshold

When terminal ice thickness of floating ice shelf is less than this threshold, it will be calved off.

Type

number

Default value

50 (meters)

Option

-thickness_calving_threshold
calving.vonmises_calving.Glen_exponent

Glen exponent in ice flow law for von Mises calving

Type

number

Default value

3 (pure number)

Option

-vonmises_calving_n
calving.vonmises_calving.flow_law

The custom flow law for the von Mises stress computation

Type

keyword

Default value

gpbld

Choices

arr, arrwarm, gpbld, hooke, isothermal_glen, pb
calving.vonmises_calving.sigma_max

Set maximum tensile stress. Note references [90] use 1.0e6 Pa.

Type

number

Default value

1e+06 (Pa)

Option

-vonmises_calving_calving_sigma_max
calving.vonmises_calving.threshold_file

Name of the file containing the spatially-variable vonmises_calving_threshold.

Type

string

Default value

empty

Option

-vonmises_calving_threshold_file
calving.vonmises_calving.use_custom_flow_law

Use custom flow law in the von Mises stress computation

Type

flag

Default value

no

Option

-vonmises_calving_use_custom_flow_law
constants.fresh_water.density

density of fresh water

Type

number

Default value

1000 (kg meter-3)
constants.fresh_water.latent_heat_of_fusion

latent heat of fusion for water [75]

Type

number

Default value

334000 (Joule / kg)
constants.fresh_water.melting_point_temperature

melting point of pure water

Type

number

Default value

273.15 (Kelvin)
constants.fresh_water.specific_heat_capacity

at melting point T_0 [75]

Type

number

Default value

4170 (Joule / (kg Kelvin))
constants.global_ocean_area

area of the global ocean [118]

Type

number

Default value

3.625e+14 (meter2)
constants.ice.beta_Clausius_Clapeyron

Clausius-Clapeyron constant relating melting temperature and pressure: \(\beta = dT / dP\) [24]

Type

number

Default value

7.9e-08 (Kelvin / Pascal)
constants.ice.density

\(\rho_i\); density of ice in ice sheet

Type

number

Default value

910 (kg meter-3)
constants.ice.grain_size

Default constant ice grain size to use with the Goldsby-Kohlstedt [25] flow law

Type

number

Default value

1 (mm)

Option

-ice_grain_size
constants.ice.specific_heat_capacity

specific heat capacity of pure ice at melting point T_0

Type

number

Default value

2009 (Joule / (kg Kelvin))
constants.ice.thermal_conductivity

= W m-1 K-1; thermal conductivity of pure ice

Type

number

Default value

2.1 (Joule / (meter Kelvin second))
constants.ideal_gas_constant

ideal gas constant

Type

number

Default value

8.31441 (Joule / (mol Kelvin))
constants.sea_water.density

density of sea water

Type

number

Default value

1028 (kg meter-3)
constants.sea_water.salinity

salinity of sea water

Type

number

Default value

35 (g / kg)
constants.sea_water.specific_heat_capacity

at 35 psu, value taken from Kaye and Laby, section 2.7.9

Type

number

Default value

3985 (Joule / (kg Kelvin))
constants.standard_gravity

acceleration due to gravity on Earth geoid

Type

number

Default value

9.81 (meter second-2)
energy.allow_temperature_above_melting

If set to “yes”, allow temperatures above the pressure-malting point in the cold mode temperature code. Used by some verifiaction tests.

Type

flag

Default value

no
energy.basal_melt.use_grounded_cell_fraction

If geometry.grounded_cell_fraction is set, use the fractional floatation mask to interpolate the basal melt rate at the grounding line between grounded and floating values.

Type

flag

Default value

true

Option

-subgl_basal_melt
energy.bedrock_thermal.conductivity

= W m-1 K-1; for bedrock used in thermal model [7]

Type

number

Default value

3 (Joule / (meter Kelvin second))
energy.bedrock_thermal.density

for bedrock used in thermal model

Type

number

Default value

3300 (kg meter-3)
energy.bedrock_thermal.file

Name of the file containing the geothermal flux field bheatflx. Leave empty to read it from the input.file.

Type

string

Default value

empty
energy.bedrock_thermal.specific_heat_capacity

for bedrock used in thermal model [7]

Type

number

Default value

1000 (Joule / (kg Kelvin))
energy.ch_warming.average_channel_spacing

Average spacing between elements of the cryo-hydrologic system (controls the rate of heat transfer from the CH system into the ice).

Type

number

Default value

20 (meters)
energy.ch_warming.enabled

Enable the cryo-hydrologic warming model

Type

flag

Default value

no
energy.ch_warming.residual_water_fraction

residual water fraction in the cryo-hydrologic system at the end of a melt season

Type

number

Default value

0.005 (pure number)
energy.ch_warming.temperate_ice_thermal_conductivity_ratio

ratio of thermal conductivities of temperate and cold ice in the cryo-hydrologic system

Type

number

Default value

1 (pure number)
energy.drainage_maximum_rate

0.05 year-1; maximum rate at which liquid water fraction in temperate ice could possibly drain; see [35]

Type

number

Default value

1.58444e-09 (second-1)
energy.drainage_target_water_fraction

liquid water fraction (omega) above which drainage occurs, but below which there is no drainage; see [35]

Type

number

Default value

0.01 (1)
energy.enabled

Solve energy conservation equations.

Type

flag

Default value

yes
energy.enthalpy.cold_bulge_max

= (2009 J kg-1 K-1) * (30 K); maximum amount by which advection can reduce the enthalpy of a column of ice below its surface enthalpy value

Type

number

Default value

60270 (Joule / kg)
energy.enthalpy.temperate_ice_thermal_conductivity_ratio

K in cold ice is multiplied by this fraction to give K0 in [35]

Type

number

Default value

0.1 (pure number)
energy.margin_exclude_horizontal_advection

Exclude horizontal advection of energy at grid points near ice margins. See energy.margin_ice_thickness_limit.

Type

flag

Default value

yes
energy.margin_exclude_strain_heating

Exclude strain heating at grid points near ice margins. See energy.margin_ice_thickness_limit.

Type

flag

Default value

yes
energy.margin_exclude_vertical_advection

Exclude vertical advection of energy at grid points near ice margins. See energy.margin_ice_thickness_limit.

Type

flag

Default value

yes
energy.margin_ice_thickness_limit

use special margin treatment at grid points with a neighbor with the thickness below this limit.

Type

number

Default value

100 (meters)
energy.max_low_temperature_count

Maximum number of grid points with ice temperature below energy.minimum_allowed_temperature.

Type

integer

Default value

10 (count)

Option

-max_low_temps
energy.minimum_allowed_temperature

Minimum allowed ice temperature

Type

number

Default value

200 (Kelvin)

Option

-low_temp
energy.temperature_based

Use cold ice (i.e. not polythermal) methods.

Type

flag

Default value

no
energy.temperature_dependent_thermal_conductivity

If yes, use varkenthSystemCtx class in the energy step. It is base on formula (4.37) in [56]. Otherwise use enthSystemCtx, which has temperature-independent thermal conductivity set by constant ice.thermal_conductivity.

Type

flag

Default value

no

Option

-vark
enthalpy_converter.T_reference

= T_0 in enthalpy formulas in [35]

Type

number

Default value

223.15 (Kelvin)
enthalpy_converter.relaxed_is_temperate_tolerance

Tolerance within which ice is treated as temperate (cold-ice mode and diagnostics).

Type

number

Default value

0.001 (Kelvin)
flow_law.Hooke.A

\(A_{\text{Hooke}} = (1/B_0)^n\) where n=3 and \(B_0\) = 1.928 \(a^{1/3}\) Pa. See [79]

Type

number

Default value

4.42165e-09 (Pascal-3 second-1)
flow_law.Hooke.C

See [79]

Type

number

Default value

0.16612 (Kelvin^k)
flow_law.Hooke.Q

Activation energy, see [79]

Type

number

Default value

78800 (Joule / mol)
flow_law.Hooke.Tr

See [79]

Type

number

Default value

273.39 (Kelvin)
flow_law.Hooke.k

See [79]

Type

number

Default value

1.17 (pure number)
flow_law.Paterson_Budd.A_cold

Paterson-Budd \(A_\text{cold}\), see [76]

Type

number

Default value

3.61e-13 (Pascal-3 / second)
flow_law.Paterson_Budd.A_warm

Paterson-Budd \(A_\text{warm}\), see [76]

Type

number

Default value

1730 (Pascal-3 / second)
flow_law.Paterson_Budd.Q_cold

Paterson-Budd \(Q_\text{cold}\), see [76]

Type

number

Default value

60000 (Joule / mol)
flow_law.Paterson_Budd.Q_warm

Paterson-Budd \(Q_\text{warm}\), see [76]

Type

number

Default value

139000 (Joule / mol)
flow_law.Paterson_Budd.T_critical

Paterson-Budd critical temperature, see [76]

Type

number

Default value

263.15 (Kelvin)
flow_law.Schoof_regularizing_length

Regularizing length (Schoof definition)

Type

number

Default value

1000 (km)
flow_law.Schoof_regularizing_velocity

Regularizing velocity (Schoof definition)

Type

number

Default value

1 (meter / year)
flow_law.gpbld.water_frac_coeff

coefficient in Glen-Paterson-Budd flow law for extra dependence of softness on liquid water fraction (omega) [56], [77]

Type

number

Default value

181.25 (pure number)
flow_law.gpbld.water_frac_observed_limit

maximum value of liquid water fraction omega for which softness values are parameterized by [77]; used in Glen-Paterson-Budd-Lliboutry-Duval flow law; compare [35]

Type

number

Default value

0.01 (1)
flow_law.isothermal_Glen.ice_softness

ice softness used by the isothermal Glen flow law [34]

Type

number

Default value

3.1689e-24 (Pascal-3 second-1)
fracture_density.borstad_limit

Model fracture growth according to the constitutive law in [96] (Eq. 4), ignoring fracture_density.gamma.

Type

flag

Default value

no

Option

-constitutive_stress_limit
fracture_density.constant_fd

Keep fracture density fields constant in time but include its softening effect.

Type

flag

Default value

no

Option

-constant_fd
fracture_density.constant_healing

Use a constant healing rate \(-\gamma_h \dot{\epsilon}_h\) independent of the local strain rate.

Type

flag

Default value

no

Option

-constant_healing
fracture_density.enabled

Model the fracture density using computed to stresses and strain rates.

Type

flag

Default value

no

Option

-fractures
fracture_density.fd2d_scheme

Use an alternative transport scheme to reduce numerical diffusion (Eq. 10 in [95])

Type

flag

Default value

no

Option

-scheme_fd2d
fracture_density.fracture_weighted_healing

Multiply the healing rate by \(1 - D\), i.e. assume that highly damaged ice heals slower. This mechanism can be combined with fracture_density.constant_healing.

Type

flag

Default value

no

Option

-fracture_weighted_healing
fracture_density.gamma

fracture growth constant \(\gamma\)

Type

number

Default value

1 (1)

Option

-fracture_gamma
fracture_density.gamma_h

fracture healing constant \(\gamma_{h}\)

Type

number

Default value

0 (1)

Option

-fracture_gamma_h
fracture_density.healing_threshold

fracture healing strain rate threshold \(\dot \epsilon_{h}\)

Type

number

Default value

2e-10 (1/s)

Option

-fracture_healing_threshold
fracture_density.include_grounded_ice

Model fracture density in grounded areas (e.g. along ice stream shear zones) in addition to ice shelves

Type

flag

Default value

no

Option

-do_frac_on_grounded
fracture_density.initiation_threshold

fracture initiation stress threshold \(\sigma_{\text{cr}}\)

Type

number

Default value

70000 (Pa)

Option

-fracture_initiation_threshold
fracture_density.lefm

Use the mixed-mode fracture toughness stress criterion based on Linear Elastic Fracture Mechanics, Eqs. 8-9 in [95]

Type

flag

Default value

no

Option

-lefm
fracture_density.max_shear_stress

Use the maximum shear stress criterion for fracture formation (Tresca or Guest criterion in literature), which is more stringent than the default von Mises criterion, see Eq. 7 in [95]

Type

flag

Default value

no

Option

-max_shear
fracture_density.phi0

Fracture density value used at grid points where ice velocity is prescribed. This assumes that all ice entering a shelf at bc_mask locations has the same fracture density.

Type

number

Default value

0 (1)

Option

-phi0
fracture_density.softening_lower_limit

Parameter controlling the strength of the feedback of damage on the ice flow. If \(1\): no feedback, if \(0\): full feedback (\(\epsilon\) in Eq. 6 in [95])

Type

number

Default value

1 (1)

Option

-fracture_softening
frontal_melt.constant.melt_rate

default melt rate used by the constant frontal_melt model

Type

number

Default value

1 (m / day)

Option

-frontal_melt_rate
frontal_melt.discharge_given.file

Name of the file containing climate forcing fields.

Type

string

Default value

empty

Option

-frontal_melt_discharge_given_file
frontal_melt.discharge_given.periodic

If true, interpret forcing data as periodic in time

Type

flag

Default value

no
frontal_melt.given.file

Name of the file containing climate forcing fields.

Type

string

Default value

empty

Option

-frontal_melt_given_file
frontal_melt.given.periodic

If true, interpret forcing data as periodic in time

Type

flag

Default value

no
frontal_melt.include_floating_ice

Apply frontal melt to all grid icy cells next to ocean cells

Type

flag

Default value

no
frontal_melt.models

Comma-separated list of frontal melt models and modifiers. (Leave empty to disable.)

Type

string

Default value

empty

Option

-frontal_melt
frontal_melt.routing.file

Name of the file containing climate forcing fields.

Type

string

Default value

empty

Option

-frontal_melt_routing_file
frontal_melt.routing.parameter_a

parameter A in eqn. 1 in [119]

Type

number

Default value

0.0003 (m-alpha day^(alpha-1) Celsius-beta)
frontal_melt.routing.parameter_b

parameter B in eqn. 1 in [119]

Type

number

Default value

0.15 (m day^(alpha-1) Celsius-beta)
frontal_melt.routing.periodic

If true, interpret forcing data as periodic in time

Type

flag

Default value

no
frontal_melt.routing.power_alpha

exponent \(\alpha\) in eqn. 1 in [119]

Type

number

Default value

0.39 (1)
frontal_melt.routing.power_beta

exponent \(\beta\) in eqn. 1 in [119]

Type

number

Default value

1.18 (1)
geometry.front_retreat.prescribed.file

Name of the file containing the maximum ice extent mask land_ice_area_fraction_retreat

Type

string

Default value

empty

Option

-front_retreat_file
geometry.front_retreat.prescribed.periodic

If true, interpret forcing data as periodic in time

Type

flag

Default value

no
geometry.front_retreat.use_cfl

apply CFL criterion for eigen-calving rate front retreat

Type

flag

Default value

false

Option

-front_retreat_cfl
geometry.front_retreat.wrap_around

If true, wrap around domain boundaries. This may be needed in some regional synthetic geometry setups.

Type

flag

Default value

false

Option

-front_retreat_wrap_around
geometry.grounded_cell_fraction

Linear interpolation scheme (“LI” in Gladstone et al. 2010) expanded to two dimensions is used if switched on in order to evaluate the position of the grounding line on a subgrid scale.

Type

flag

Default value

false

Option

-subgl
geometry.ice_free_thickness_standard

If ice is thinner than this standard then the mask is set to MASK_ICE_FREE_BEDROCK or MASK_ICE_FREE_OCEAN.

Type

number

Default value

0.01 (meters)
geometry.part_grid.enabled

apply partially filled grid cell scheme

Type

flag

Default value

no

Option

-part_grid
geometry.part_grid.max_iterations

maximum number of residual redistribution iterations

Type

integer

Default value

10 (count)
geometry.remove_icebergs

identify and kill detached ice-shelf areas

Type

flag

Default value

no

Option

-kill_icebergs
geometry.update.enabled

Solve the mass conservation equation

Type

flag

Default value

yes

Option

-mass
geometry.update.use_basal_melt_rate

Include basal melt rate in the continuity equation

Type

flag

Default value

yes

Option

-bmr_in_cont
grid.Lbz

Thickness of the thermal bedrock layer. (Inactive if grid.Mbz < 2)

Type

number

Default value

1000 (meters)

Option

-Lbz
grid.Lx

Default computational box is 3000 km x 3000 km (= 2 Lx x 2 Ly) in horizontal.

Type

number

Default value

1.5e+06 (meters)
grid.Ly

Default computational box is 3000 km x 3000 km (= 2 Lx x 2 Ly) in horizontal.

Type

number

Default value

1.5e+06 (meters)
grid.Lz

Height of the computational domain.

Type

number

Default value

4000 (meters)

Option

-Lz
grid.Mbz

Number of thermal bedrock layers; 1 level corresponds to no bedrock.

Type

integer

Default value

1 (count)

Option

-Mbz
grid.Mx

Number of grid points in the x direction.

Type

integer

Default value

61 (count)

Option

-Mx
grid.My

Number of grid points in the y direction.

Type

integer

Default value

61 (count)

Option

-My
grid.Mz

Number of vertical grid levels in the ice.

Type

integer

Default value

31 (count)

Option

-Mz
grid.allow_extrapolation

Allow extrapolation during regridding.

Type

flag

Default value

no

Option

-allow_extrapolation
grid.ice_vertical_spacing

vertical spacing in the ice

Type

keyword

Default value

quadratic

Choices

quadratic, equal

Option

-z_spacing
grid.lambda

Vertical grid spacing parameter. Roughly equal to the factor by which the grid is coarser at an end away from the ice-bedrock interface.

Type

number

Default value

4 (pure number)
grid.max_stencil_width

Maximum width of the finite-difference stencil used in PISM.

Type

integer

Default value

2 (count)
grid.periodicity

horizontal grid periodicity

Type

keyword

Default value

xy

Choices

none, x, y, xy

Option

-periodicity
grid.recompute_longitude_and_latitude

Re-compute longitude and latitude using grid information and provided projection parameters. Requires PROJ.

Type

flag

Default value

yes
grid.registration

horizontal grid registration

Type

keyword

Default value

center

Choices

center, corner
hydrology.add_water_input_to_till_storage

Add surface input to water stored in till. If no it will be added to the transportable water.

Type

flag

Default value

yes
hydrology.cavitation_opening_coefficient

c_1 in notes; coefficient of cavitation opening term in evolution of layer thickness in hydrology::Distributed

Type

number

Default value

0.5 (meter-1)

Option

-hydrology_cavitation_opening_coefficient
hydrology.creep_closure_coefficient

c_2 in notes; coefficient of creep closure term in evolution of layer thickness in hydrology::Distributed

Type

number

Default value

0.04 (pure number)

Option

-hydrology_creep_closure_coefficient
hydrology.distributed.init_p_from_steady

if “yes”, initialize subglacial water pressure from P(W) formula that applies in steady state

Type

flag

Default value

no

Option

-hydrology_init_p_form_steady
hydrology.distributed.sliding_speed_file

name of the file containing velbase_mag, the basal sliding speed to use with hydrology.distributed.init_p_from_steady

Type

string

Default value

empty

Option

-hydrology_sliding_speed_file
hydrology.gradient_power_in_flux

power \(\beta\) in Darcy’s law \(q = - k W^{\alpha} |\nabla \psi|^{\beta-2} \nabla \psi\), for subglacial water layer; used by hydrology::Routing and hydrology::Distributed

Type

number

Default value

1.5 (pure number)

Option

-hydrology_gradient_power_in_flux
hydrology.hydraulic_conductivity

= k in notes; lateral conductivity, in Darcy’s law, for subglacial water layer; units depend on powers alpha = hydrology.thickness_power_in_flux and beta = hydrology_potential_gradient_power_in_flux; used by hydrology::Routing and hydrology::Distributed

Type

number

Default value

0.001 (`m^{2 \beta - \alpha} s^{2 \beta - 3} kg^{1-\beta}`)

Option

-hydrology_hydraulic_conductivity
hydrology.maximum_time_step

maximum allowed time step length used by hydrology::Routing and hydrology::Distributed

Type

number

Default value

1 (365days)
hydrology.model

Basal hydrology sub-model.

Type

keyword

Default value

null

Choices

null, routing, steady, distributed

Option

-hydrology
hydrology.null_diffuse_till_water

Diffuse stored till water laterally. See equation (11) of [29]

Type

flag

Default value

no
hydrology.null_diffusion_distance

diffusion distance for till water thickness; see equation (11) in [29]; only active if hydrology.null_diffuse_till_water is set

Type

number

Default value

20000 (meters)
hydrology.null_diffusion_time

diffusion time for till water thickness; see equation (11) in [29]; only active if hydrology.null_diffuse_till_water is set

Type

number

Default value

1000 (365days)
hydrology.regularizing_porosity

phi_0 in notes; regularizes pressure equation by multiplying time derivative term

Type

number

Default value

0.01 (pure number)

Option

-hydrology_regularizing_porosity
hydrology.roughness_scale

W_r in notes; roughness scale determining maximum amount of cavitation opening in hydrology::Distributed

Type

number

Default value

0.1 (meters)

Option

-hydrology_roughness_scale
hydrology.routing.include_floating_ice

Route subglacial water under ice shelves. This may be appropriate if a shelf is close to floatation. Note that this has no effect on ice flow.

Type

flag

Default value

no
hydrology.steady.flux_update_interval

interval between updates of the steady state flux

Type

number

Default value

1 (365days)
hydrology.steady.input_rate_scaling

input rate scaling

Type

number

Default value

1e+07 (seconds)
hydrology.steady.n_iterations

maxinum number of iterations to use in while estimating steady-state water flux

Type

integer

Default value

7500 (count)
hydrology.steady.potential_delta

potential adjustment used to fill sinks (smaller values require more iterations but produce fewer artifacts)

Type

number

Default value

10000 (Pa)
hydrology.steady.potential_n_iterations

maxinum number of iterations to take while pre-processing hydraulic potential

Type

integer

Default value

1000 (count)
hydrology.steady.volume_ratio

water volume ratio used as the stopping criterion

Type

number

Default value

0.1 (1)
hydrology.surface_input.file

Name of the file containing water_input_rate, the rate at which water from the ice surface is added to the subglacial hydrology system

Type

string

Default value

empty
hydrology.surface_input.periodic

If true, interpret forcing data as periodic in time

Type

flag

Default value

no
hydrology.surface_input_from_runoff

Use surface runoff as surface input.

Type

flag

Default value

no
hydrology.thickness_power_in_flux

power \(\alpha\) in Darcy’s law \(q = - k W^{\alpha} |\nabla \psi|^{\beta-2} \nabla \psi\), for subglacial water layer; used by hydrology::Routing and hydrology::Distributed

Type

number

Default value

1.25 (1)

Option

-hydrology_thickness_power_in_flux
hydrology.tillwat_decay_rate

rate at which tillwat is reduced to zero, in absence of other effects like input

Type

number

Default value

1 (mm / year)

Option

-hydrology_tillwat_decay_rate
hydrology.tillwat_max

maximum effective thickness of the water stored in till

Type

number

Default value

2 (meters)

Option

-hydrology_tillwat_max
input.bootstrap

It true, use bootstrapping heuristics when initializing PISM.

Type

flag

Default value

no

Option

-bootstrap
input.file

Input file name

Type

string

Default value

empty

Option

-i
input.forcing.buffer_size

number of 2D climate forcing records to keep in memory; = 5 years of monthly records

Type

integer

Default value

60 (count)
input.forcing.time_extrapolation

If ‘true’, time-dependent forcing inputs are extrapolated in time

Type

flag

Default value

false
input.regrid.file

Regridding (input) file name

Type

string

Default value

empty

Option

-regrid_file
input.regrid.vars

Comma-separated list of variables to regrid. Leave empty to regrid all model state variables.

Type

string

Default value

empty

Option

-regrid_vars
inverse.design.cH1

weight of derivative part of an H1 norm for inversion design variables

Type

number

Default value

0 (1)

Option

-inv_design_cH1
inverse.design.cL2

weight of derivative-free part of an H1 norm for inversion design variables

Type

number

Default value

1 (1)

Option

-inv_design_cL2
inverse.design.func

functional used for inversion design variables

Type

keyword

Default value

sobolevH1

Choices

sobolevH1, tv

Option

-inv_design_func
inverse.design.param

parameterization of design variables used during inversion

Type

keyword

Default value

exp

Choices

ident, trunc, square, exp

Option

-inv_design_param
inverse.design.param_tauc_eps

tiny yield stress used as a substitute for 0 in some tauc parameterizations

Type

number

Default value

100 (Pascal)
inverse.design.param_tauc_scale

typical size of yield stresses

Type

number

Default value

100000 (Pascal)
inverse.design.param_trunc_tauc0

transition point of change to linear behaviour for design variable parameterization type trunc

Type

number

Default value

1000 (Pascal)
inverse.log_ratio_scale

Reference scale for log-ratio functionals

Type

number

Default value

10 (pure number)

Option

-inv_log_ratio_scale
inverse.max_iterations

maximum iteration count

Type

integer

Default value

1000 (count)

Option

-inv_max_it
inverse.ssa.hardav_max

Maximum allowed value of hardav for inversions with bound constraints

Type

number

Default value

1e+10 (Pascal second^(1/3))
inverse.ssa.hardav_min

Minimum allowed value of hardav for inversions with bound constraints

Type

number

Default value

0 (Pascal second^(1/3))
inverse.ssa.length_scale

typical length scale for rescaling derivative norms

Type

number

Default value

50000 (meters)
inverse.ssa.method

algorithm to use for SSA inversions

Type

keyword

Default value

tikhonov_lmvm

Choices

sd, nlcg, ign, tikhonov_lmvm, tikhonov_cg, tikhonov_blmvm, tikhonov_lcl, tikhonov_gn

Option

-inv_method
inverse.ssa.tauc_max

Maximum allowed value of tauc for inversions with bound constraints

Type

number

Default value

5e+07 (Pascal)
inverse.ssa.tauc_min

Minimum allowed value of tauc for inversions with bound constraints

Type

number

Default value

0 (Pascal)
inverse.ssa.tv_exponent

Lebesgue exponent for pseudo-TV norm

Type

number

Default value

1.2 (pure number)

Option

-inv_ssa_tv_exponent
inverse.ssa.velocity_eps

tiny size of ice velocities during inversion

Type

number

Default value

0.1 (meter / year)
inverse.ssa.velocity_scale

typical size of ice velocities expected during inversion

Type

number

Default value

100 (meter / year)
inverse.state_func

functional used for inversion design variables

Type

keyword

Default value

meansquare

Choices

meansquare, log_ratio, log_relative

Option

-inv_state_func
inverse.tikhonov.atol

absolute threshold for Tikhonov stopping criterion

Type

number

Default value

1e-10 (meter / year)

Option

-tikhonov_atol
inverse.tikhonov.penalty_weight

penalty parameter for Tikhonov inversion

Type

number

Default value

1 (1)

Option

-tikhonov_penalty
inverse.tikhonov.ptol

threshold for reaching desired misfit for adaptive Tikhonov algorithms

Type

number

Default value

0.1 (pure number)

Option

-tikhonov_ptol
inverse.tikhonov.rtol

relative threshold for Tikhonov stopping criterion

Type

number

Default value

0.05 (1)

Option

-tikhonov_rtol
inverse.use_design_prior

Use prior from inverse data file as initial guess.

Type

flag

Default value

yes

Option

-inv_use_design_prior
inverse.use_zeta_fixed_mask

Enforce locations where the parameterized design variable should be fixed. (Automatically determined if not provided)

Type

flag

Default value

yes

Option

-inv_use_zeta_fixed_mask
ocean.anomaly.file

Name of the file containing shelf basal mass flux offset fields.

Type

string

Default value

empty

Option

-ocean_anomaly_file
ocean.anomaly.periodic

If true, interpret forcing data as periodic in time

Type

flag

Default value

no
ocean.cache.update_interval

update interval of the cache ocean modifier

Type

integer

Default value

10 (365days)

Option

-ocean_cache_update_interval
ocean.constant.melt_rate

default melt rate used by the constant ocean model (computed as \(Q / (L \rho_i)\))

Type

number

Default value

0.0519142 (m / year)

Option

-shelf_base_melt_rate
ocean.delta_MBP.file

Name of the file containing melange back-pressure offsets

Type

string

Default value

empty
ocean.delta_MBP.melange_thickness

Melange thickness (assumed to be constant in space and time)

Type

number

Default value

100 (meters)

Option

-melange_thickness
ocean.delta_MBP.periodic

If true, interpret forcing data as periodic in time

Type

flag

Default value

no
ocean.delta_T.file

Name of the file containing temperature offsets.

Type

string

Default value

empty

Option

-ocean_delta_T_file
ocean.delta_T.periodic

If true, interpret forcing data as periodic in time

Type

flag

Default value

no
ocean.delta_mass_flux.file

Name of the file containing sub-shelf mass flux offsets.

Type

string

Default value

empty

Option

-ocean_delta_mass_flux_file
ocean.delta_mass_flux.periodic

If true, interpret forcing data as periodic in time

Type

flag

Default value

no
ocean.delta_sl.file

Name of the file containing sea level offsets.

Type

string

Default value

empty

Option

-ocean_delta_sl_file
ocean.delta_sl.periodic

If true, interpret forcing data as periodic in time

Type

flag

Default value

no
ocean.delta_sl_2d.file

Name of the file containing climate forcing fields.

Type

string

Default value

empty
ocean.delta_sl_2d.periodic

If true, interpret forcing data as periodic in time

Type

flag

Default value

no
ocean.frac_MBP.file

Name of the file containing melange back-pressure scaling.

Type

string

Default value

empty

Option

-ocean_frac_MBP_file
ocean.frac_MBP.periodic

If true, interpret forcing data as periodic in time

Type

flag

Default value

no
ocean.frac_mass_flux.file

Name of the file containing sub-shelf mass flux scaling.

Type

string

Default value

empty

Option

-ocean_frac_mass_flux_file
ocean.frac_mass_flux.periodic

If true, interpret forcing data as periodic in time

Type

flag

Default value

no
ocean.given.file

Name of the file containing climate forcing fields.

Type

string

Default value

empty

Option

-ocean_given_file
ocean.given.periodic

If true, interpret forcing data as periodic in time

Type

flag

Default value

no
ocean.models

Comma-separated list of ocean models and modifiers.

Type

string

Default value

constant

Option

-ocean
ocean.pico.continental_shelf_depth

Specifies the depth up to which oceanic input temperatures and salinities are averaged over the continental shelf areas in front of the ice shelf cavities.

Type

number

Default value

-800 (meters)

Option

-continental_shelf_depth
ocean.pico.exclude_ice_rises

If set to true, grounding lines of ice rises are excluded in the geometrical routines that determine the ocean boxes; using this option is recommended.

Type

flag

Default value

yes

Option

-exclude_icerises
ocean.pico.file

Specifies the NetCDF file containing potential temperature (theta_ocean), salinity (salinity_ocean) and ocean basins (basins).

Type

string

Default value

empty

Option

-ocean_pico_file
ocean.pico.heat_exchange_coefficent

Sets the coefficient for turbulent heat exchange from the ambient ocean across the boundary layer beneath the ice shelf base.

Type

number

Default value

2e-05 (meters second-1)

Option

-gamma_T
ocean.pico.maximum_ice_rise_area

Specifies an area threshold that separates ice rises from continental regions.

Type

number

Default value

100000 (km2)
ocean.pico.number_of_boxes

For each ice shelf the number of ocean boxes is determined by interpolating between 1 and number_of_boxes depending on its size and geometry such that larger ice shelves are resolved with more boxes; a value of 5 is suitable for the Antarctic setup.

Type

integer

Default value

5 (pure number)

Option

-number_of_boxes
ocean.pico.overturning_coefficent

Sets the overturning strength coefficient.

Type

number

Default value

1e+06 (meters6 seconds-1 kg-1)

Option

-overturning_coeff
ocean.pico.periodic

If true, interpret forcing data as periodic in time

Type

flag

Default value

no
ocean.pik_melt_factor

dimensionless tuning parameter in the -ocean pik ocean heat flux parameterization; see [3]

Type

number

Default value

0.005 (1)

Option

-meltfactor_pik
ocean.runoff_to_ocean_melt.b

parameter B in eqn. 1 in [120]

Type

number

Default value

0.15 (1)
ocean.runoff_to_ocean_melt.file

Name of the file containing the delta_T variable used to scale ocean melt

Type

string

Default value

empty

Option

-ocean_runoff_smb
ocean.runoff_to_ocean_melt.power_alpha

exponent \(\alpha\) in eqn. 1 in [119]

Type

number

Default value

0.54 (1)
ocean.runoff_to_ocean_melt.power_beta

exponent \(\beta\) in eqn. 1 in [119]

Type

number

Default value

1.17 (1)
ocean.sub_shelf_heat_flux_into_ice

= J meter-2 second-1; naively chosen default value for heat from ocean; see comments in pism::ocean::Constant::shelf_base_mass_flux().

Type

number

Default value

0.5 (W meter-2)
ocean.th.clip_salinity

Clip shelf base salinity so that it is in the range [4, 40] k/kg. See [11].

Type

flag

Default value

yes

Option

-clip_shelf_base_salinity
ocean.th.file

Name of the file containing climate forcing fields.

Type

string

Default value

empty

Option

-ocean_th_file
ocean.th.gamma_S

Turbulent salt transfer coefficient. See [11].

Type

number

Default value

5.05e-07 (m s-1)

Option

-gamma_T
ocean.th.gamma_T

Turbulent heat transfer coefficient. See [11].

Type

number

Default value

0.0001 (m s-1)

Option

-gamma_T
ocean.th.periodic

If true, interpret forcing data as periodic in time

Type

flag

Default value

no
output.ISMIP6

Follow ISMIP6 conventions (units, variable names, “standard names”) when writing output variables.

Type

flag

Default value

false
output.ISMIP6_extra_variables

Comma-separated list of fields reported by models participating in ISMIP6 simulations.

Type

string

Default value

lithk, orog, topg, hfgeoubed, acabf, libmassbfgr, libmassbffl, dlithkdt, velsurf, zvelsurf, velbase, zvelbase, velmean, litemptop, litempbotgr, litempbotfl, strbasemag, licalvf, lifmassbf, sftgif, sftgrf, sftflf
output.ISMIP6_ts_variables

Comma-separated list of scalar variables (time series) reported by models participating in ISMIP6 simulations.

Type

string

Default value

lim, limnsw, iareagr, iareafl, tendacabf, tendlibmassbf, tendlibmassbffl, tendlicalvf, tendlifmassbf
output.backup_interval

wall-clock time between automatic backups

Type

number

Default value

1 (hours)

Option

-backup_interval
output.backup_size

The “size” of a backup file. See parameters output.sizes.medium, output.sizes.big_2d, output.sizes.big

Type

keyword

Default value

small

Choices

none, small, medium, big_2d, big

Option

-backup_size
output.compression_level

Compression level for 2D and 3D output variables (if supported by output.format)

Type

integer

Default value

0 (count)
output.extra.append

Append to an existing output file. No effect if file does not yet exist, and no effect if output.extra.split is set.

Type

flag

Default value

no

Option

-extra_append
output.extra.file

Name of the file that will contain spatially-variable diagnostics. Should be different from output.file_name.

Type

string

Default value

empty

Option

-extra_file
output.extra.split

Save spatially-variable diagnostics to separate files (one per time record).

Type

flag

Default value

no

Option

-extra_split
output.extra.stop_missing

Stop if requested variable is not available instead of warning.

Type

flag

Default value

yes

Option

-extra_stop_missing
output.extra.times

List or a range of times defining reporting intervals for spatially-variable diagnostics.

Type

string

Default value

empty

Option

-extra_times
output.extra.vars

Comma-separated list of spatially-variable diagnostics.

Type

string

Default value

empty

Option

-extra_vars
output.file_name

The file to save final model results to.

Type

string

Default value

unnamed.nc

Option

-o
output.fill_value

_FillValue used when saving diagnostic quantities

Type

number

Default value

-2e+09 (none)
output.format

The I/O format used for spatial fields; netcdf3 is the default, netcd4_parallel is available if PISM was built with parallel NetCDF-4, and pnetcdf is available if PISM was built with PnetCDF.

Type

keyword

Default value

netcdf3

Choices

netcdf3, netcdf4_serial, netcdf4_parallel, pnetcdf, pio_pnetcdf, pio_netcdf4p, pio_netcdf4c, pio_netcdf

Option

-o_format
output.ice_free_thickness_standard

If ice is thinner than this standard then a grid cell is considered ice-free for purposes of reporting glacierized area, volume, etc.

Type

number

Default value

10 (meters)
output.pio.base

Rank of the first I/O task

Type

integer

Default value

0 (count)
output.pio.n_writers

Number of I/O tasks to use

Type

integer

Default value

1 (count)
output.pio.stride

Offset between I/O tasks

Type

integer

Default value

1 (count)
output.runtime.area_scale_factor_log10

an integer; log base 10 of scale factor to use for area (in km^2) in summary line to stdout

Type

integer

Default value

6 (pure number)

Option

-summary_area_scale_factor_log10
output.runtime.time_unit_name

Time units used when printing model time, time step, and maximum horizontal velocity at summary to stdout. Must be valid udunits for time. (E.g. choose from year,month,day,hour,minute,second.)

Type

string

Default value

year
output.runtime.time_use_calendar

Whether to use the current calendar when printing model time in summary to stdout.

Type

flag

Default value

yes
output.runtime.viewer.size

default diagnostic viewer size (number of pixels of the longer side)

Type

integer

Default value

320 (count)

Option

-view_size
output.runtime.viewer.variables

comma-separated list of map-plane diagnostic quantities to view at runtime

Type

string

Default value

empty

Option

-view
output.runtime.volume_scale_factor_log10

an integer; log base 10 of scale factor to use for volume (in km^3) in summary line to stdout

Type

integer

Default value

6 (pure number)

Option

-summary_vol_scale_factor_log10
output.size

The “size” of an output file. See parameters output.sizes.medium, output.sizes.big_2d, output.sizes.big

Type

keyword

Default value

medium

Choices

none, small, medium, big_2d, big

Option

-o_size
output.sizes.big

Comma-separated list of variables to write to the output (in addition to model_state variables and variables listed in output.sizes.medium and output.sizes.big_2d) if big output size is selected. Does not include fields written by sub-models.

Type

string

Default value

cts, liqfrac, temp, temp_pa, uvel, vvel, wvel, wvel_rel
output.sizes.big_2d

Comma-separated list of variables to write to the output (in addition to model_state variables and variables listed in output.sizes.medium) if big_2d output size is selected. Does not include fields written by boundary models.

Type

string

Default value

age, bfrict, bheatflx, bmelt, bwp, bwprel, dbdt, effbwp, enthalpybase, enthalpysurf, flux_divergence, hardav, hydroinput, lat, litho_temp, lon, nuH, rank, tempbase, tempicethk, tempicethk_basal, temppabase, tempsurf, thk, thksmooth, tillphi, topg, velbar, velbase, wallmelt, wvelbase
output.sizes.medium

Comma-separated list of variables to write to the output (in addition to model_state variables) if medium output size (the default) is selected. Does not include fields written by sub-models.

Type

string

Default value

bwat, bwatvel, climatic_mass_balance, diffusivity, enthalpy, flux, flux_mag, ice_surface_temp, liqfrac, mask, schoofs_theta, strain_rates, taub_mag, tauc, taud_mag, temp_pa, tillwat, topgsmooth, usurf, velbar_mag, velbase_mag, velsurf, velsurf_mag, wvelsurf
output.snapshot.file

Snapshot (output) file name (or prefix, if saving to individual files).

Type

string

Default value

empty

Option

-save_file
output.snapshot.size

The “size” of a snapshot file. See parameters output.sizes.medium, output.sizes.big_2d, output.sizes.big

Type

keyword

Default value

small

Choices

none, small, medium, big_2d, big

Option

-save_size
output.snapshot.split

Save model state snapshots to separate files (one per time record).

Type

flag

Default value

no

Option

-save_split
output.snapshot.times

List or a range of times to save model state snapshots at.

Type

string

Default value

empty

Option

-save_times
output.timeseries.append

If true, append to the scalar time series output file.

Type

flag

Default value

false

Option

-ts_append
output.timeseries.buffer_size

Number of scalar diagnostic time-series records to hold in memory before writing to disk. (PISM writes this many time-series records to reduce I/O costs.) Send the USR2 signal to flush time-series.

Type

integer

Default value

10000 (count)
output.timeseries.filename

Name of the file to save scalar time series to. Leave empty to disable reporting scalar time-series.

Type

string

Default value

empty

Option

-ts_file
output.timeseries.times

List or range of times defining reporting time intervals.

Type

string

Default value

empty

Option

-ts_times
output.timeseries.variables

Requested scalar (time-series) diagnostics. Leave empty to save all available diagnostics.

Type

string

Default value

empty

Option

-ts_vars
output.use_MKS

Use MKS units in output files.

Type

flag

Default value

false
regional.no_model_strip

Default width of the “no model strip” in regional setups.

Type

number

Default value

5 (km)

Option

-no_model_strip
regional.no_model_yield_stress

High yield stress used in the no_model_mask area in the regional mode.

Type

number

Default value

1000 (kPa)
regional.zero_gradient

Use zero ice thickness and ice surface gradient in the no_model_mask area.

Type

flag

Default value

false

Option

-zero_grad_where_no_model
run_info.institution

Institution name. This string is written to output files as the institution global attribute.

Type

string

Default value

empty

Option

-institution
run_info.title

Free-form string containing a concise description of the current run. This string is written to output files as the title global attribute.

Type

string

Default value

empty

Option

-title
sea_level.constant.value

Sea level elevation used by the constant sea level model

Type

number

Default value

0 (meters)
sea_level.models

Comma-separated list of sea level models and modifiers.

Type

string

Default value

constant

Option

-sea_level
stress_balance.blatter.Glen_exponent

Glen exponent in ice flow law for the Blatter stress balance solver

Type

number

Default value

3 (pure number)
stress_balance.blatter.Mz

Number of vertical grid levels in the ice

Type

integer

Default value

5 (count)

Option

-blatter_Mz
stress_balance.blatter.coarsening_factor

Coarsening factor in the \(z\) direction

Type

integer

Default value

2 (count)

Option

-blatter_coarsening_factor
stress_balance.blatter.enhancement_factor

Flow enhancement factor for the Blatter stress balance flow law

Type

number

Default value

1 (1)

Option

-blatter_e
stress_balance.blatter.flow_law

The flow law used by the Blatter-Pattyn stress balance model

Type

keyword

Default value

gpbld

Choices

arr, arrwarm, gpbld, hooke, isothermal_glen, pb
stress_balance.blatter.use_eta_transform

Use the \(\eta\) transform to improve the accuracy of the surface gradient approximation near grounded margins (see [33] for details).

Type

flag

Default value

no
stress_balance.calving_front_stress_bc

Apply CFBC condition as in [98], [37]. May only apply to some stress balances; e.g. SSAFD as of May 2011. If not set then a strength-extension is used, as in [29].

Type

flag

Default value

no

Option

-cfbc
stress_balance.ice_free_thickness_standard

If ice is thinner than this standard then a cell is considered ice-free for purposes of computing ice velocity distribution.

Type

number

Default value

10 (meters)
stress_balance.model

Stress balance model

Type

keyword

Default value

sia

Choices

none, prescribed_sliding, weertman_sliding, sia, ssa, prescribed_sliding+sia, weertman_sliding+sia, ssa+sia, blatter

Option

-stress_balance
stress_balance.prescribed_sliding.file

The name of the file containing prescribed sliding velocity (variable names: ubar, vbar).

Type

string

Default value

empty
stress_balance.sia.Glen_exponent

Glen exponent in ice flow law for SIA

Type

number

Default value

3 (pure number)

Option

-sia_n
stress_balance.sia.bed_smoother.range

half-width of smoothing domain in the bed roughness parameterization for SIA [83]; set to zero to disable

Type

number

Default value

5000 (meters)

Option

-bed_smoother_range
stress_balance.sia.bed_smoother.theta_min

minimum value of \(\theta\) in the bed roughness parameterization for SIA [83]

Type

number

Default value

0 (1)
stress_balance.sia.e_age_coupling

Couple the SIA enhancement factor to age as in [36].

Type

flag

Default value

no

Option

-e_age_coupling
stress_balance.sia.enhancement_factor

Flow enhancement factor for SIA

Type

number

Default value

1 (1)

Option

-sia_e
stress_balance.sia.enhancement_factor_interglacial

Flow enhancement factor for SIA; used for ice accumulated during interglacial periods.

Type

number

Default value

1 (1)

Option

-sia_e_interglacial
stress_balance.sia.flow_law

The SIA flow law.

Type

keyword

Default value

gpbld

Choices

arr, arrwarm, gk, gpbld, hooke, isothermal_glen, pb

Option

-sia_flow_law
stress_balance.sia.grain_size_age_coupling

Use age of the ice to compute grain size to use with the Goldsby-Kohlstedt [25] flow law

Type

flag

Default value

no

Option

-grain_size_age_coupling
stress_balance.sia.limit_diffusivity

Limit SIA diffusivity by stress_balance.sia.max_diffusivity.

Type

flag

Default value

no

Option

-limit_sia_diffusivity
stress_balance.sia.max_diffusivity

Maximum allowed diffusivity of the SIA flow. PISM stops with an error message if the SIA diffusivity exceeds this limit.

Type

number

Default value

100 (m2 s-1)
stress_balance.sia.surface_gradient_method

method used for surface gradient calculation at staggered grid points

Type

keyword

Default value

haseloff

Choices

eta, haseloff, mahaffy

Option

-gradient
stress_balance.ssa.Glen_exponent

Glen exponent in ice flow law for SSA

Type

number

Default value

3 (pure number)

Option

-ssa_n
stress_balance.ssa.compute_surface_gradient_inward

If yes then use inward first-order differencing in computing surface gradient in the SSA objects.

Type

flag

Default value

no
stress_balance.ssa.dirichlet_bc

apply SSA velocity Dirichlet boundary condition

Type

flag

Default value

no

Option

-ssa_dirichlet_bc
stress_balance.ssa.enhancement_factor

Flow enhancement factor for SSA

Type

number

Default value

1 (1)

Option

-ssa_e
stress_balance.ssa.epsilon

Initial amount of regularization in computation of product of effective viscosity and thickness (\(\nu H\)). This default value for \(\nu H\) comes e.g. from a hardness for the Ross ice shelf (\(\bar B\)) = 1.9e8 Pa \(s^{1/3}\) [68] and a typical strain rate of 0.001 1/year for the Ross ice shelf, giving \(\nu = (\bar B) / (2 \cdot 0.001^{2/3})\) = 9.49e+14 Pa s ~ 30 MPa year, the value in [87], but with a tiny thickness \(H\) of about 1 cm.

Type

number

Default value

1e+13 (Pascal second meter)

Option

-ssa_eps
stress_balance.ssa.fd.brutal_sliding

Enhance sliding speed brutally.

Type

flag

Default value

false

Option

-brutal_sliding
stress_balance.ssa.fd.brutal_sliding_scale

Brutal SSA Sliding Scale

Type

number

Default value

1 (1)

Option

-brutal_sliding_scale
stress_balance.ssa.fd.flow_line_mode

Set \(v\) (the \(y\) component of the ice velocity) to zero when assembling the system

Type

flag

Default value

false
stress_balance.ssa.fd.lateral_drag.enabled

Set viscosity at ice shelf margin next to ice free bedrock as friction parameterization

Type

flag

Default value

false
stress_balance.ssa.fd.lateral_drag.viscosity

Staggered viscosity used as side friction parameterization.

Type

number

Default value

5e+15 (Pascal second)

Option

-nu_bedrock
stress_balance.ssa.fd.max_iterations

Maximum number of Picard iterations for the ice viscosity computation, in the SSAFD object

Type

integer

Default value

300 (count)

Option

-ssafd_picard_maxi
stress_balance.ssa.fd.max_speed

Upper bound for the ice speed computed by the SSAFD solver.

Type

number

Default value

300000 (km s-1)

Option

-ssafd_max_speed
stress_balance.ssa.fd.nuH_iter_failure_underrelaxation

In event of “Effective viscosity not converged” failure, use outer iteration rule nuH <- nuH + f (nuH - nuH_old), where f is this parameter.

Type

number

Default value

0.8 (pure number)

Option

-ssafd_nuH_iter_failure_underrelaxation
stress_balance.ssa.fd.relative_convergence

Relative change tolerance for the effective viscosity in the SSAFD object

Type

number

Default value

0.0001 (1)

Option

-ssafd_picard_rtol
stress_balance.ssa.fd.replace_zero_diagonal_entries

Replace zero diagonal entries in the SSAFD matrix with :config:’basal_resistance.beta_ice_free_bedrock’ to avoid solver failures.

Type

flag

Default value

yes
stress_balance.ssa.flow_law

The SSA flow law.

Type

keyword

Default value

gpbld

Choices

arr, arrwarm, gpbld, hooke, isothermal_glen, pb

Option

-ssa_flow_law
stress_balance.ssa.method

Algorithm for computing the SSA solution.

Type

keyword

Default value

fd

Choices

fd, fem

Option

-ssa_method
stress_balance.ssa.read_initial_guess

Read the initial guess from the input file when re-starting.

Type

flag

Default value

yes

Option

-ssa_read_initial_guess
stress_balance.ssa.strength_extension.constant_nu

The SSA is made elliptic by use of a constant value for the product of viscosity (nu) and thickness (H). This value for nu comes from hardness (bar B)=1.9e8 \(Pa s^{1/3}\) [68] and a typical strain rate of 0.001 year-1: \(\nu = (\bar B) / (2 \cdot 0.001^{2/3})\). Compare the value of 9.45e14 Pa s = 30 MPa year in [87].

Type

number

Default value

9.48681e+14 (Pascal second)
stress_balance.ssa.strength_extension.min_thickness

The SSA is made elliptic by use of a constant value for the product of viscosity (nu) and thickness (H). At ice thicknesses below this value the product nu*H switches from the normal vertical integral to a constant value. The geometry itself is not affected by this value.

Type

number

Default value

50 (meters)
stress_balance.vertical_velocity_approximation

Vertical velocity FD approximation. “Upstream” uses first-order finite difference to compute u_x and v_y. Uses basal velocity to make decisions.

Type

keyword

Default value

centered

Choices

centered, upstream

Option

-vertical_velocity_approximation
stress_balance.weertman_sliding.A

Sliding parameter in the Weertman-style sliding parameterization [88]

Type

number

Default value

1.8e-16 (Pa-3 year-1 m-2)
stress_balance.weertman_sliding.k

The ratio of the basal water pressure and the ice overburden pressure in the Weertman-style sliding parameterization.

Type

number

Default value

0.2 (1)
surface.anomaly.file

Name of the file containing climate forcing fields.

Type

string

Default value

empty

Option

-surface_anomaly_file
surface.anomaly.periodic

If true, interpret forcing data as periodic in time

Type

flag

Default value

no
surface.cache.update_interval

Update interval (in 365-day years) for the -surface cache modifier.

Type

integer

Default value

10 (365days)
surface.delta_T.file

Name of the file containing temperature offsets.

Type

string

Default value

empty

Option

-surface_delta_T_file
surface.delta_T.periodic

If true, interpret forcing data as periodic in time

Type

flag

Default value

no
surface.elevation_change.file

Name of the file containing the reference surface elevation field (variable usurf).

Type

string

Default value

empty

Option

-surface_elevation_change_file
surface.elevation_change.periodic

If true, interpret forcing data as periodic in time

Type

flag

Default value

no
surface.elevation_change.smb.exp_factor

Exponential for the surface mass balance.

Type

number

Default value

0 (Kelvin-1)

Option

-smb_exp_factor
surface.elevation_change.smb.lapse_rate

Lapse rate for the surface mass balance.

Type

number

Default value

0 ((m / year) / km)

Option

-smb_lapse_rate
surface.elevation_change.smb.method

Choose the SMB adjustment method. scale: use temperature-change-dependent scaling factor. shift: use the SMB lapse rate.

Type

keyword

Default value

shift

Choices

scale, shift

Option

-smb_adjustment
surface.elevation_change.temperature_lapse_rate

Lapse rate for the temperature at the top of the ice.

Type

number

Default value

0 (K / km)

Option

-temp_lapse_rate
surface.force_to_thickness.alpha

exponential coefficient in force-to-thickness mechanism

Type

number

Default value

0.01 (year-1)

Option

-force_to_thickness_alpha
surface.force_to_thickness.ice_free_alpha_factor

surface.force_to_thickness.alpha is multiplied by this factor in areas that are ice-free according to the target ice thickness and surface.force_to_thickness.ice_free_thickness_threshold

Type

number

Default value

1 (1)

Option

-force_to_thickness_ice_free_alpha_factor
surface.force_to_thickness.ice_free_thickness_threshold

threshold of ice thickness in the force-to-thickness target field. Used to determine whether to use surface.force_to_thickness.ice_free_alpha_factor.

Type

number

Default value

1 (meters)

Option

-force_to_thickness_ice_free_thickness_threshold
surface.force_to_thickness.start_time

Starting time for the “force to thickness” modifier; the default is “start from the creation of the Earth.”

Type

number

Default value

-4.54e+09 (years)
surface.force_to_thickness_file

The name of the file to read the target ice thickness from.

Type

string

Default value

empty

Option

-force_to_thickness_file
surface.given.file

Name of the file containing climate forcing fields.

Type

string

Default value

empty

Option

-surface_given_file
surface.given.periodic

If true, interpret forcing data as periodic in time

Type

flag

Default value

no
surface.given.smb_max

Maximum climatic mass balance value (used to check input data). Corresponds to 100 m/year ice equivalent.

Type

number

Default value

91000 (kg m-2 year-1)
surface.ismip6.file

Name of the file containing climate forcing anomaly fields.

Type

string

Default value

empty

Option

-surface_ismip6_file
surface.ismip6.periodic

If true, interpret forcing data as periodic in time

Type

flag

Default value

no
surface.ismip6.reference_file

Name of the file containing reference climate forcing fields.

Type

string

Default value

empty

Option

-surface_ismip6_reference_file
surface.models

Comma-separated list of surface models and modifiers.

Type

string

Default value

given

Option

-surface
surface.pdd.air_temp_all_precip_as_rain

threshold temperature above which all precipitation is rain; must exceed surface.pdd.air_temp_all_precip_as_snow to avoid division by zero, because difference is in a denominator

Type

number

Default value

275.15 (Kelvin)
surface.pdd.air_temp_all_precip_as_snow

threshold temperature below which all precipitation is snow

Type

number

Default value

273.15 (Kelvin)
surface.pdd.balance_year_start_day

day of year for October 1st, beginning of the balance year in northern latitudes.

Type

integer

Default value

274 (ordinal day number)
surface.pdd.factor_ice

EISMINT-Greenland value [7]; = (8 mm liquid-water-equivalent) / (pos degree day)

Type

number

Default value

0.00879121 (meter / (Kelvin day))
surface.pdd.factor_snow

EISMINT-Greenland value [7]; = (3 mm liquid-water-equivalent) / (pos degree day)

Type

number

Default value

0.0032967 (meter / (Kelvin day))
surface.pdd.fausto.T_c

= -1 + 273.15; for formula (6) in [1]

Type

number

Default value

272.15 (Kelvin)
surface.pdd.fausto.T_w

= 10 + 273.15; for formula (6) in [1]

Type

number

Default value

283.15 (Kelvin)
surface.pdd.fausto.beta_ice_c

water-equivalent thickness; for formula (6) in [1]

Type

number

Default value

0.015 (meter / (Kelvin day))
surface.pdd.fausto.beta_ice_w

water-equivalent thickness; for formula (6) in [1]

Type

number

Default value

0.007 (meter / (Kelvin day))
surface.pdd.fausto.beta_snow_c

water-equivalent thickness; for formula (6) in [1]

Type

number

Default value

0.003 (meter / (Kelvin day))
surface.pdd.fausto.beta_snow_w

water-equivalent thickness; for formula (6) in [1]

Type

number

Default value

0.003 (meter / (Kelvin day))
surface.pdd.fausto.enabled

Set PDD parameters using formulas (6) and (7) in [1]

Type

flag

Default value

false

Option

-pdd_fausto
surface.pdd.fausto.latitude_beta_w

latitude below which to use warm case, in formula (6) in [1]

Type

number

Default value

72 (degree_north)
surface.pdd.firn_compaction_to_accumulation_ratio

How much firn as a fraction of accumulation is turned into ice

Type

number

Default value

0.75 (1)
surface.pdd.firn_depth_file

The name of the file to read the firn_depth from.

Type

string

Default value

empty

Option

-pdd_firn_depth_file
surface.pdd.interpret_precip_as_snow

Interpret precipitation as snow fall.

Type

flag

Default value

no
surface.pdd.max_evals_per_year

maximum number of times the PDD scheme will ask for air temperature and precipitation to build location-dependent time series for computing (expected) number of positive degree days and snow accumulation; the default means the PDD uses weekly samples of the annual cycle; see also surface.pdd.std_dev.value

Type

integer

Default value

52 (count)
surface.pdd.method

PDD implementation method

Type

keyword

Default value

expectation_integral

Choices

expectation_integral, repeatable_random_process, random_process

Option

-pdd_method
surface.pdd.positive_threshold_temp

temperature used to determine meaning of “positive” degree day

Type

number

Default value

273.15 (Kelvin)
surface.pdd.refreeze

EISMINT-Greenland value [7]

Type

number

Default value

0.6 (1)
surface.pdd.refreeze_ice_melt

If set to “yes”, refreeze surface.pdd.refreeze fraction of melted ice, otherwise all of the melted ice runs off.

Type

flag

Default value

yes
surface.pdd.std_dev.file

The name of the file to read air_temp_sd (standard deviation of air temperature) from.

Type

string

Default value

empty

Option

-pdd_sd_file
surface.pdd.std_dev.lapse_lat_base

standard deviationis is a function of latitude, with value surface.pdd.std_dev.value at this latitude; this value is only active if surface.pdd.std_dev.lapse_lat_rate is nonzero

Type

number

Default value

72 (degree_north)
surface.pdd.std_dev.lapse_lat_rate

standard deviation is a function of latitude, with rate of change with respect to latitude given by this constant

Type

number

Default value

0 (Kelvin / degree_north)
surface.pdd.std_dev.param_a

Parameter \(a\) in \(\Sigma = aT + b\), with \(T\) in degrees C. Used only if surface.pdd.std_dev.use_param is set to yes.

Type

number

Default value

-0.15 (pure number)
surface.pdd.std_dev.param_b

Parameter \(b\) in \(\Sigma = aT + b\), with \(T\) in degrees C. Used only if surface.pdd.std_dev.use_param is set to yes.

Type

number

Default value

0.66 (Kelvin)
surface.pdd.std_dev.periodic

If true, interpret air_temp_sd read from surface.pdd.std_dev.file as periodic in time

Type

flag

Default value

no
surface.pdd.std_dev.use_param

Parameterize standard deviation as a linear function of air temperature over ice-covered grid cells. The region of application is controlled by geometry.ice_free_thickness_standard.

Type

flag

Default value

no
surface.pdd.std_dev.value

standard deviation of daily temp variation; = EISMINT-Greenland value [7]

Type

number

Default value

5 (Kelvin)
surface.pressure

atmospheric pressure; = pressure at ice surface

Type

number

Default value

0 (Pascal)
surface.temp_to_runoff_a

a in runoff=a * temp + b

Type

number

Default value

0.5 (K-1)
time.calendar

The calendar to use.

Type

keyword

Default value

365_day

Choices

standard, gregorian, proleptic_gregorian, noleap, 365_day, 360_day, julian

Option

-calendar
time.dimension_name

The name of the time dimension in PISM output files.

Type

string

Default value

time
time.eemian_end

End of the Eemian interglacial period. See [86].

Type

number

Default value

-114500 (years)
time.eemian_start

Start of the Eemian interglacial period. See [86].

Type

number

Default value

-132000 (years)
time.end

End time, interpreted relative to time.reference_date.

Type

string

Default value

empty

Option

-ye
time.file

Name of the file used to set time.start, time.end, time.calendar, and time.reference_date

Type

string

Default value

empty

Option

-time_file
time.file.continue

If true, don’t set time.start using time.file (helpful when continuing an interrupted simulation)

Type

flag

Default value

false
time.holocene_start

Start of the Holocene interglacial period. See [86].

Type

number

Default value

-11000 (years)
time.reference_date

year-month-day; reference date used for calendar computations and in PISM output files

Type

string

Default value

1-1-1
time.run_length

Run length

Type

number

Default value

1000 (365days)

Option

-y
time.start

Start time, interpreted relative to time.reference_date.

Type

string

Default value

empty

Option

-ys
time_stepping.adaptive_ratio

Adaptive time stepping ratio for the explicit scheme for the mass balance equation; [30], inequality (25)

Type

number

Default value

0.12 (1)

Option

-adapt_ratio
time_stepping.assume_bed_elevation_changed

If set, assume that bed elevation changes every time step. If not set, PISM tries to avoid unnecessary computations if the bed deformation model did not update bed elevation (to reduce the computational cost a little bit).

Type

flag

Default value

no
time_stepping.count_steps

If yes, IceModel::run() will count the number of time steps it took. Sometimes useful for performance evaluation. Counts all steps, regardless of whether processes (mass continuity, energy, velocity, …) occurred within the step.

Type

flag

Default value

no

Option

-count_steps
time_stepping.hit_extra_times

Modify the time-stepping mechanism to hit times requested using output.extra.times.

Type

flag

Default value

yes

Option

-extra_force_output_times
time_stepping.hit_multiples

Hit every X years, where X is specified using this parameter. Use 0 to disable.

Type

integer

Default value

0 (years)

Option

-timestep_hit_multiples
time_stepping.hit_save_times

Modify the time-stepping mechanism to hit times requested using output.snapshot.times.

Type

flag

Default value

no

Option

-save_force_output_times
time_stepping.hit_ts_times

Modify the time-stepping mechanism to hit times requested using output.timeseries.times.

Type

flag

Default value

no
time_stepping.maximum_time_step

Maximum allowed time step length

Type

number

Default value

60 (365days)

Option

-max_dt
time_stepping.resolution

Time steps are rounded down to be a multiple of this number (set to zero to allow arbitrary time step lengths)

Type

number

Default value

1 (seconds)
time_stepping.skip.enabled

Use the temperature, age, and SSA stress balance computation skipping mechanism.

Type

flag

Default value

no

Option

-skip
time_stepping.skip.max

Number of mass-balance steps, including SIA diffusivity updates, to perform before a the temperature, age, and SSA stress balance computations are done

Type

integer

Default value

10 (count)

Option

-skip_max