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.

In the example above (command-line option -constants.standard_gravity 10), the provided value of acceleration due to gravity (\(10\)) is expected to use units listed in this section (here: meters per second squared).

PISM also allows using other units supported by UDUNITS. For example, the following command line options are equivalent:

-grid.dx 5000
-grid.dx 5km
-dx "5e6 mm"

The following are equivalent and enable solving the age equation:

-age.enabled
-age.enabled on
-age.enabled yes
-age.enabled true
-age.enabled 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 [145]

Type:

number

Default value:

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

latitude-dependence coefficient for formula (2) in [145]

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 [145]

Type:

number

Default value:

314.98 (kelvin)
atmosphere.fausto_air_temp.d_mj

= 14.70+273.15; base temperature for formula (2) in [145]

Type:

number

Default value:

287.85 (kelvin)
atmosphere.fausto_air_temp.gamma_ma

= -6.309 / 1km; mean slope lapse rate for formula (1) in [145]

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 [145]

Type:

number

Default value:

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

longitude-dependence coefficient for formula (1) in [145]

Type:

number

Default value:

0.0672 (kelvin / degree_west)
atmosphere.fausto_air_temp.kappa_mj

longitude-dependence coefficient for formula (2) in [145]

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 [145]

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.air_temperature_interpolation

Temporal interpolation type used for near-surface air temperatures

Type:

keyword

Default value:

piecewise_linear

Choices:

piecewise_linear, piecewise_constant
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 [31]

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 [146]; 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 [21]

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 [88]

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 [19]

Type:

number

Default value:

0.12 (pure number)

Option:

-till_compressibility_coefficient
basal_yield_stress.mohr_coulomb.till_effective_fraction_overburden

\(\delta\) in [91]; \(\delta P_o \le N_{\text{till}} \le P_o\) 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 [19]

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 [19]

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

Option:

-topg_to_phi
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)

Option:

-phi_max
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)

Option:

-phi_min
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)

Option:

-topg_max
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)

Option:

-topg_min
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 [96], [32].

Type:

integer

Default value:

4 (count)
bed_deformation.lithosphere_flexural_rigidity

lithosphere flexural rigidity used by the bed deformation model. See [96], [32]

Type:

number

Default value:

5e+24 (Newton meter)
bed_deformation.mantle_density

half-space (mantle) density used by the bed deformation model. See [96], [32]

Type:

number

Default value:

3300 (kg meter^-3)
bed_deformation.mantle_viscosity

half-space (mantle) viscosity used by the bed deformation model. See [96], [32]

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 [96], 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
bed_deformation.update_interval

Interval between updates of bed deformation models

Type:

number

Default value:

10 (365days)
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 [99], [52] 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 [104]

Type:

number

Default value:

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

Damage law exponent [104]

Type:

number

Default value:

0.43 (1)
calving.hayhurst_calving.sigma_threshold

Damage threshold stress [104]

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 [103] 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 [80]

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 [80]

Type:

number

Default value:

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

area of the global ocean [112]

Type:

number

Default value:

3.625e+14 (meter^2)
constants.ice.beta_Clausius_Clapeyron

Clausius-Clapeyron constant relating melting temperature and pressure: \(\beta = dT / dP\) [147]

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 [70] 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 [148]

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 [148]

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 [22]

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 [22]

Type:

number

Default value:

0.01 (1)
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 [22]

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.model

Energy balance model

Type:

keyword

Default value:

enthalpy

Choices:

enthalpy, cold, none

Option:

-energy
energy.temperature_dependent_thermal_conductivity

If yes, use varkenthSystemCtx class in the energy step. It is base on formula (4.37) in [55]. 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 [22]

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 [36]

Type:

number

Default value:

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

Paterson-Budd \(A_\text{warm}\), see [36]

Type:

number

Default value:

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

Paterson-Budd \(Q_\text{cold}\), see [36]

Type:

number

Default value:

60000 (Joule / mol)
flow_law.Paterson_Budd.Q_warm

Paterson-Budd \(Q_\text{warm}\), see [36]

Type:

number

Default value:

139000 (Joule / mol)
flow_law.Paterson_Budd.T_critical

Paterson-Budd critical temperature, see [36]

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) [55], [35]

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 [35]; used in Glen-Paterson-Budd-Lliboutry-Duval flow law; compare [22]

Type:

number

Default value:

0.01 (1)
flow_law.isothermal_Glen.ice_softness

ice softness used by the isothermal Glen flow law [59]

Type:

number

Default value:

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

Model fracture growth according to the constitutive law in [110] (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 [109])

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 [109]

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 [109]

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 [109])

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.open_ocean_margins_only

Apply frontal melt parameterizations only at ice fronts bordering ice-free ocean areas that are connected to the open ocean

Type:

flag

Default value:

no
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 [149]

Type:

number

Default value:

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

parameter B in eqn. 1 in [149]

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 [149]

Type:

number

Default value:

0.39 (1)
frontal_melt.routing.power_beta

exponent \(\beta\) in eqn. 1 in [149]

Type:

number

Default value:

1.18 (1)
geometry.front_retreat.minimum_time_step

Minimum allowed time step length. Increase this to keep calving models from slowing PISM down too much.

Type:

number

Default value:

0.01 (365day)
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

Half-width of the computational box in the \(X\) direction

Type:

number

Default value:

no default (km)

Option:

-Lx
grid.Ly

Half-width of the computational box in the \(Y\) direction

Type:

number

Default value:

no default (km)

Option:

-Ly
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 (see also grid.dx)

Type:

integer

Default value:

no default (count)

Option:

-Mx
grid.My

Number of grid points in the y direction (see also grid.dy)

Type:

integer

Default value:

no default (count)

Option:

-My
grid.Mz

Number of vertical grid levels in the ice.

Type:

integer

Default value:

31 (count)

Option:

-Mz
grid.Nx

Number of MPI sub-domains in the x direction (uses default if negative)

Type:

integer

Default value:

no default (count)

Option:

-Nx
grid.Ny

Number of MPI sub-domains in the y direction (uses default if negative)

Type:

integer

Default value:

no default (count)

Option:

-Ny
grid.allow_extrapolation

Allow extrapolation during regridding.

Type:

flag

Default value:

no

Option:

-allow_extrapolation
grid.dx

Grid resolution in the X direction (overrides grid.Mx)

Type:

number

Default value:

no default (meter)

Option:

-dx
grid.dy

Grid resolution in the Y direction (overrides grid.My)

Type:

number

Default value:

no default (meter)

Option:

-dy
grid.file

grid definition file used to initialize the horizontal computational grid

Type:

string

Default value:

empty
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.procs_x

comma-separated list of custom sub-domain widths in the X direction

Type:

string

Default value:

empty
grid.procs_y

comma-separated list of custom sub-domain widths in the Y direction

Type:

string

Default value:

empty
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 [10]

Type:

flag

Default value:

no
hydrology.null_diffusion_distance

diffusion distance for till water thickness; see equation (11) in [10]; 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 [10]; 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.adaptive

Adaptive Tikhonov threshold

Type:

flag

Default value:

false

Option:

-tikhonov_adaptive
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
isochrones.bootstrapping.n_layers

number of isochronal layers created during bootstrapping

Type:

integer

Default value:

0 (count)
isochrones.deposition_times

List or a range of deposition times used to create isochronal layers

Type:

string

Default value:

empty
isochrones.max_n_layers

maximum number of isochronal layers

Type:

integer

Default value:

100 (count)
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 (km^2)
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 (count)

Option:

-number_of_boxes
ocean.pico.overturning_coefficent

Sets the overturning strength coefficient.

Type:

number

Default value:

1e+06 (meters^6 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 [52]

Type:

number

Default value:

0.005 (1)

Option:

-meltfactor_pik
ocean.runoff_to_ocean_melt.b

parameter B in eqn. 1 in [150]

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 [149]

Type:

number

Default value:

0.54 (1)
ocean.runoff_to_ocean_melt.power_beta

exponent \(\beta\) in eqn. 1 in [149]

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 [151].

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 [151].

Type:

number

Default value:

5.05e-07 (m s^-1)

Option:

-gamma_T
ocean.th.gamma_T

Turbulent heat transfer coefficient. See [151].

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.checkpoint.exit

If true PISM will exit with after checkpointing.

Type:

flag

Default value:

no
output.checkpoint.exit_code

Exit code to use if output.checkpoint.exit is set.

Type:

integer

Default value:

85 (none)
output.checkpoint.file

If set, save model checkpoints to this file, otherwise build the name by appending _checkpoint to output.file.

Type:

string

Default value:

empty
output.checkpoint.interval

wall-clock time between checkpointing

Type:

number

Default value:

1 (hours)

Option:

-checkpoint_interval
output.checkpoint.size

The “size” of a checkpoint 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:

-checkpoint_size
output.compression_level

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

Type:

integer

Default value:

0 (none)
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.

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

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

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.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 (none)

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 (none)

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 [58] for details).

Type:

flag

Default value:

no
stress_balance.calving_front_stress_bc

Apply CFBC condition as in [98], [17]. 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 [10].

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 [66]; 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 [66]

Type:

number

Default value:

0 (1)
stress_balance.sia.e_age_coupling

Couple the SIA enhancement factor to age as in [44].

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 [70] 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 (m^2 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 \(s^{1/3}\) [62] 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 [63], 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.absolute_tolerance

Absolute tolerance used by the SNES-based SSAFD solver (converged if the infinity norm of the residual is below this)

Type:

number

Default value:

100 (Pascal)
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.extrapolate_at_margins

Extrapolate SSA velocity to ice-free cells near the margin to improve SSA velocities at advancing ice fronts

Type:

flag

Default value:

true
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.nuH_viewer_size

size of the run time viewer (inactive if zero)

Type:

integer

Default value:

0 (count)
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.fd.upstream_surface_slope_approximation

Use an upstream-biased finite difference to estimate the surface slope in the driving stress computation

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, fd_snes, 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 \(Pa s^{1/3}\) [62] 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 [63].

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 [71]

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.debm_simple.air_temp_all_precip_as_rain

Threshold temperature above which all precipitation is interpreted as rain; must exceed surface.debm_simple.air_temp_all_precip_as_snow

Type:

number

Default value:

275.15 (kelvin)
surface.debm_simple.air_temp_all_precip_as_snow

Threshold temperature below which all precipitation is interpreted as snow

Type:

number

Default value:

273.15 (kelvin)
surface.debm_simple.albedo_input.file

Name of the file containing the variable albedo to use instead of parameterizing it

Type:

string

Default value:

empty
surface.debm_simple.albedo_input.periodic

If true, interpret forcing data as periodic in time

Type:

flag

Default value:

no
surface.debm_simple.albedo_max

Maximum (“fresh snow”) albedo in albedo parametrization (tuning parameter)

Type:

number

Default value:

0.82 (1)
surface.debm_simple.albedo_min

Minimum (“bare ice”) albedo in albedo parametrization

Type:

number

Default value:

0.47 (1)
surface.debm_simple.albedo_ocean

Albedo of ice-free ocean

Type:

number

Default value:

0.1 (1)
surface.debm_simple.albedo_slope

Slope in albedo parametrization (tuning parameter)

Type:

number

Default value:

-790 (m^2 s kg^-1)
surface.debm_simple.c1

Tuning parameter in the temperature-driven melt contribution

Type:

number

Default value:

29 (W m^-2 K^-1)
surface.debm_simple.c2

Tuning parameter controlling the melt offset

Type:

number

Default value:

-93 (W m^-2)
surface.debm_simple.interpret_precip_as_snow

If true, interpret all precipitation as snow

Type:

flag

Default value:

no
surface.debm_simple.max_evals_per_year

Maximum number of air temperature and precipitation samples per year used to build location-dependent time series for computing melt and snow accumulation; the default means use weekly samples of the annual cycle

Type:

integer

Default value:

52 (count)
surface.debm_simple.melting_threshold_temp

Threshold temperature below which no melting occurs

Type:

number

Default value:

266.65 (kelvin)
surface.debm_simple.paleo.eccentricity

Eccentricity of the Earth’s orbit

Type:

number

Default value:

0.0167 (1)
surface.debm_simple.paleo.enabled

If true, use orbital parameters to compute top of the atmosphere insolation

Type:

flag

Default value:

false

Option:

-debm_simple_paleo
surface.debm_simple.paleo.file

File containing orbital parameters (eccentricity, obliquity, perihelion_longitude) for paleo-simulations

Type:

string

Default value:

empty

Option:

-debm_simple_paleo_file
surface.debm_simple.paleo.obliquity

Mean obliquity (axial tilt) of the Earth

Type:

number

Default value:

23.44 (degree)
surface.debm_simple.paleo.perihelion_longitude

Mean longitude of the perihelion relative to the vernal equinox, in the geocentric ecliptic coordinate system

Type:

number

Default value:

282.947 (degree)
surface.debm_simple.paleo.periodic

If true, interpret forcing data as periodic in time

Type:

flag

Default value:

no
surface.debm_simple.phi

Threshold solar elevation angle above which melt is possible

Type:

number

Default value:

17.5 (degree)
surface.debm_simple.positive_threshold_temp

Temperature threshold used to define the “positive” temperature

Type:

number

Default value:

273.15 (kelvin)
surface.debm_simple.refreeze

Refreeze fraction: this fraction of snow melt is assumed to re-freeze. See also surface.debm_simple.refreeze_ice_melt.

Type:

number

Default value:

0.6 (1)
surface.debm_simple.refreeze_ice_melt

If set to ‘yes’, refreeze surface.debm_simple.refreeze fraction of melted ice, otherwise all of the melted ice runs off.

Type:

flag

Default value:

no
surface.debm_simple.solar_constant

Mean solar electromagnetic radiation (total solar irradiance) per unit area [152]

Type:

number

Default value:

1361 (W m^-2)
surface.debm_simple.std_dev

Standard deviation of daily near-surface air temperature variation

Type:

number

Default value:

5 (kelvin)
surface.debm_simple.std_dev.file

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

Type:

string

Default value:

empty

Option:

-debm_simple_sd_file
surface.debm_simple.std_dev.param.a

Parameter \(a\) in \(\sigma = \max(a\, (T - T_{\text{melting}}) + b, 0)\). Used only if surface.debm_simple.std_dev.param.enabled is set to yes.

Type:

number

Default value:

-0.15 (1)
surface.debm_simple.std_dev.param.b

Parameter \(b\) in \(\sigma = \max(a\, (T - T_{\text{melting}}) + b, 0)\). Used only if surface.debm_simple.std_dev.param.enabled is set to yes.

Type:

number

Default value:

0.66 (kelvin)
surface.debm_simple.std_dev.param.enabled

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.debm_simple.std_dev.periodic

If true, interpret forcing data as periodic in time

Type:

flag

Default value:

no
surface.debm_simple.tau_a_intercept

Intercept in the parametrization of atmosphere transmissivity

Type:

number

Default value:

0.65 ()
surface.debm_simple.tau_a_slope

Slope in the parametrization of atmosphere transmissivity

Type:

number

Default value:

3.2e-05 (m^-1)
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.elevation_dependent.M_limit_max

climatic mass balance at elevations below \(h_{\text{min}}\) (inactive if equal to surface.elevation_dependent.M_limit_min)

Type:

number

Default value:

0 (m year^-1)

Option:

-M_limit_max
surface.elevation_dependent.M_limit_min

climatic mass balance at elevations above \(h_{\text{max}}\) (inactive if equal to surface.elevation_dependent.M_limit_max)

Type:

number

Default value:

0 (m year^-1)

Option:

-M_limit_min
surface.elevation_dependent.M_max

\(M_{\text{max}}\), maximum climatic mass balance in the elevation range \([h_{\text{min}}, h_{\text{max}}]\)

Type:

number

Default value:

4 (m year^-1)

Option:

-M_max
surface.elevation_dependent.M_min

\(M_{\text{min}}\), minimum climatic mass balance in the elevation range \([h_{\text{min}}, h_{\text{max}}]\)

Type:

number

Default value:

-3 (m year^-1)

Option:

-M_min
surface.elevation_dependent.T_max

maximum ice surface temperature \(T_{\text{max}}\)

Type:

number

Default value:

0 (degree_Celsius)

Option:

-T_max
surface.elevation_dependent.T_min

minimum ice surface temperature \(T_{\text{min}}\)

Type:

number

Default value:

-5 (degree_Celsius)

Option:

-T_min
surface.elevation_dependent.z_ELA

equilibrium line altitude \(z_{\text{ELA}}\)

Type:

number

Default value:

1450 (meters)

Option:

-z_ELA
surface.elevation_dependent.z_M_max

surface elevation corresponding to the maximum mass balance \(M_{\text{max}}\)

Type:

number

Default value:

1700 (meters)

Option:

-z_M_max
surface.elevation_dependent.z_M_min

surface elevation corresponding to the minimum mass balance \(M_{\text{min}}\)

Type:

number

Default value:

1100 (meters)

Option:

-z_M_min
surface.elevation_dependent.z_T_max

surface elevation corresponding to the maximum ice surface temperature \(T_{\text{max}}\)

Type:

number

Default value:

1350 (meters)

Option:

-z_T_max
surface.elevation_dependent.z_T_min

surface elevation corresponding to the minimum ice surface temperature \(T_{\text{min}}\)

Type:

number

Default value:

1325 (meters)

Option:

-z_T_min
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.file

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

Type:

string

Default value:

empty

Option:

-force_to_thickness_file
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.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.mass_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.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.factor_ice

EISMINT-Greenland value [148]; = (8 mm liquid-water-equivalent) / (pos degree day)

Type:

number

Default value:

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

EISMINT-Greenland value [148]; = (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 [145]

Type:

number

Default value:

272.15 (kelvin)
surface.pdd.fausto.T_w

= 10 + 273.15; for formula (6) in [145]

Type:

number

Default value:

283.15 (kelvin)
surface.pdd.fausto.beta_ice_c

water-equivalent thickness; for formula (6) in [145]

Type:

number

Default value:

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

water-equivalent thickness; for formula (6) in [145]

Type:

number

Default value:

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

water-equivalent thickness; for formula (6) in [145]

Type:

number

Default value:

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

water-equivalent thickness; for formula (6) in [145]

Type:

number

Default value:

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

Set PDD parameters using formulas (6) and (7) in [145]

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 [145]

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 [148]

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 [148]

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 [69].

Type:

number

Default value:

-114500 (years)
time.eemian_start

Start of the Eemian interglacial period. See [69].

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 [69].

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:

0001-1-1
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; [16], 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.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