CESM2.2.1 CISM Namelist Definitions

Determines whether extra diagnostics are printed in the cism log file
Default: false

Input file
Default: For startup runs or hybrid runs with CISM_OBSERVED_IC=TRUE, a resolution-dependent
         initial conditions file (e.g., gland20.input_c150415.nc).
         For branch/hybrid runs with CISM_OBSERVED_IC=FALSE, a restart file name
         built based on RUN_REFCASE and RUN_REFDATE.

Code describing how the solid ice runoff flux (i.e., calving) should
be routed.
ocn: all solid ice goes to the ocean component
ice: all solid ice goes to the sea ice component
Default: ocn

Name of top-level configuration file for CISM
(Determined by scripts -- cannot be set by user)

If this is set to true, it sets the mass balance timestep to 1 day.
This means the ice dynamics is called after one day of climate simulation.
THIS IS ONLY FOR TESTING OF COUPLING PROCEDURES, NOT TO BE USED FOR SCIENCE.

If true, zero out all fluxes sent to the GCM
Default: Depends on GLC_TWO_WAY_COUPLING xml variable

0: Do not let the ice sheet evolve (hold ice state fixed at initial condition)
1: Let the ice sheet evolve
Default: 1

Ice time-step multiplier: allows asynchronous climate-ice coupling
Default: (use hard-coded default- currently 1)

Node spacing in x-direction (m)
Default: resolution-dependent

Node spacing in y-direction (m)
Default: resolution-dependent

Number of nodes in x-direction
Default: resolution-dependent

Global boundary conditions
0: Doubly periodic
1: Free outflow; scalars in global halo set to zero
2: No penetration; outflow set to zero at global boundaries (only supported for Glissade dycore)
Default: 0 for cism1, 1 for cism2

Number of nodes in y-direction
Default: resolution-dependent

Number of nodes in z-direction
Default: 11

thermal conductivity of lithosphere (W m-1 K-1)
Only relevant if gthf = 2
Default: (use hard-coded default - currently 3.3)

Number of vertical layers
Only relevant if gthf = 2
Default: (use hard-coded default - currently 20)

1: 1D calculations
3: 3D calculations
Only relevant if gthf = 2
Default: (use hard-coded default - currently 1)

Number of time steps for spinning up GTHF calculations
Only relevant if gthf = 2
Default: (use hard-coded default - currently 0)

Density of lithosphere (kg m-3)
Only relevant if gthf = 2
Default: (use hard-coded default - currently 3300.)

Depth below sea-level at which geothermal heat gradient is applied (m)
Only relevant if gthf = 2
Default: (use hard-coded default - currently -5000.)

Specific heat capacity of lithosphere (J kg-1 K-1)
Only relevant if gthf = 2
Default: (use hard-coded default - currently 1000.)

Initial surface temperature (degrees C)
Only relevant if gthf = 2
Default: (use hard-coded default - currently 2.)

Flag that indicates whether ice inception away from the main ice sheet is blocked
Default: false

Maximum number of nonlinear iterations to be used by the Glissade velocity solver
Default: 50

Flag that indicates whether ice caps are removed and added to the calving flux
Default: false

Flag that indicates which Stokes approximation to use with the Glissade dycore.
Not valid for other dycores.
-1: Shallow-ice approximation, Glide-type calculation (uses glissade_velo_sia)
0: Shallow-ice approximation, vertical-shear stresses only (uses glissade_velo_higher)
1: Shallow-shelf approximation, horizontal-plane stresses only (uses glissade_velo_higher)
2: Blatter-Pattyn approximation with both vertical-shear and horizontal-plane stresses (uses glissade_velo_higher)
3: Vertically integrated 'L1L2' approximation with vertical-shear and horizontal-plane stresses (uses glissade_velo_higher)
4: Depth-integrated viscosity approximation based on Goldberg (2011) (uses glissade_velo_higher)
Default: 4

Flag that describes how beta terms are assembled in the Glissade finite-element calculation
0: Standard finite-element calculation (which effectively smooths beta)
1: Apply local value of beta at each vertex
Default: 1

Flag that describes how the basal friction heat flux is computed in the Glissade finite-element calculation
Not valid for other dycores
0: Standard finite-element calculation summing over quadrature points
1: Apply local value of beta*(u^2 + v^2) at each vertex
Default: 1

Flag that describes how driving-stress terms are assembled in the Glissade finite-element calculation
Not valid for other dycores
0: Standard finite-element calculation (which effectively smooths the driving stress)
1: Apply local value of driving stress at each vertex
Default: 1

Basal boundary condition for higher order dynamical core
0: spatially uniform value (low value of 10 Pa yr-1 by default)
1: large value for frozen bed, lower value for bed at pressure melting point
2: treat beta value as a till yield stress (in Pa) using Picard iteration 
3: pseudo-plastic basal sliding law; can model linear, power-law or plastic behavior
4: very large value for beta to enforce no slip everywhere 
5: beta field passed in from .nc input file as part of standard i/o
6: no slip everywhere (using Dirichlet BC rather than large beta)
7: treat beta value as till yield stress (in Pa) using Newton-type iteration (in development)
8: beta field as prescribed for ISMIP-HOM test C (serial only)
9: power law
10: Coulomb friction law using effective pressure, with flwa from lowest ice layer
11: Coulomb friction law using effective pressure, with constant basal flwa
12: basal stress is the minimum of Coulomb and power-law values, as in Tsai et al. (2015)
13: power law based on effective pressure
14: simple hard-coded pattern (useful for debugging)
Default: 3

Basal water depth
0: Set to zero everywhere
1: Set to constant everywhere, to force T = Tpmp.
2: Local basal till model with constant drainage
Default: 2

Flag that indicates whether to use a subgrid calving front parameterization
0: No subgrid calving front parameterization
1: Use subgrid calving front parameterization
Default: 0

Method for computing the dissipation during the temperature calculation
-1: no dissipation
0: 0-order SIA approx.
1: 1st order solution (e.g., Blatter-Pattyn)
Default: 1

Flag that describes effective pressure calculation for higher order dynamical core
0: N = overburden pressure, rhoi*grav*thck
1: N is reduced where the bed is at or near the pressure melting point
2: N is reduced where there is melting at the bed
3: N is reduced due to the connection of subglacial water to the ocean
4: N is reduced where basal water is present
Default: 4

How effective viscosity is computed for higher-order dynamical core
0: constant value
1: multiple of flow factor
2: compute from effective strain rate
Default: 2

Flag that indicates how to compute the flotation function at and near vertices in the Glissade dycore
Not valid for other dycores
Only applicable for which_ho_ground=1
0: f_flotation = (-rhow*b/rhoi*H) = f_pattyn; <=1 for grounded, > 1 for floating
1: f_flotation = (rhoi*H)/(-rhow*b) = 1/f_pattyn; >=1 for grounded, < 1 for floating
2: f_flotation = -rhow*b - rhoi*H = ocean cavity thickness; <=0 for grounded, > 0 for floating
Default: 2

Which gradient operator to use in the Glissade dycore.
Not valid in other dycores.
NOTE: Upstream may be better for ice evolution because it damps checkerboard noise.
0: Centered gradient
1: First-order accurate upstream gradient
2: Second-order accurate upstream gradient
Default: 0

How to compute the gradient at the ice margin in the Glissade dycore.
Not valid for other dycores.
Note: Gradients are always computed at edges with ice on both sides.
The methods differ in whether gradients are computed when an ice-covered cell
lies above an ice-free cell (land or ocean).
0: Compute edge gradient when either cell is ice-covered
1: Compute edge gradient for ice-covered cell above ice-free land (not ocean)
2: Compute edge gradient only when both cells have ice
Default: 1

Flag that indicates how the grounded ice fraction is computed in the Glissade dycore
Not valid for other dycores
0: fground = 0 in floating cells (based on flotation condition), else fground = 1 
1: [NOT SUPPORTED] fground between 0 and 1 (inclusive), based on a grounding line parameterization
2: fground = 1 in all cells
Default: 0

Flag that indicates how to compute bmlt_float in partly grounded cells
0: Apply bmlt_float in all floating cells, including partly grounded cells
1: Do not apply bmlt_float in partly grounded cells
Default: 0

Method for solving the nonlinear iteration when solving the first-order momentum balance
0: use the standard Picard iteration
1: use Jacobian Free Newton Krylov (JFNK) method [GLAM only]
Default: 1 for dycore = 1, 0 for dycore = 2

Flag that indicates which Stokes preconditioner to use in the Glissade dycore.
Not valid for other dycores.
0: No preconditioner
1: Diagonal preconditioner
2: Physics-based shallow-ice preconditioner
Default: 1

Method for computing residual in Payne/Price dynamical core
0: maxval
1: maxval ignoring basal velocity
2: mean value
3: L2 norm of system residual, Ax-b=resid
4: L2 norm of system residual relative to rhs, |Ax-b|/|b|
Default: 4

Method for solving the sparse linear system that arises from the higher-order solver
-1: SLAP (serial) Preconditioned conjugate gradient, incomplete Cholesky preconditioner
0: SLAP (serial) Biconjugate gradient, incomplete LU preconditioner
1: SLAP (serial) GMRES, incomplete LU preconditioner
2: Native PCG, parallel-enabled, standard solver
3: Native PCG, parallel-enabled, Chronopoulos-Gear solver
4: standalone interface to Trilinos
The use of trilinos is NOT SUPPORTED in CESM runs.
Default: 3 if dycore = 2, 1 if dycore = 1 and cism_use_trilinos = FALSE

0: vertical thermal solve before transport solve
1: vertical thermal solve after transport solve
2: vertical thermal solve split; both before and after transport solve
Default: 2

0: fluid mantle, isostatic adjustment happens instantaneously
1: relaxing mantle, mantle is approximated by a half-space
Only relevant if isostasy = 1
Default: (use hard-coded default - currently 1)

Flexural rigidity of the lithosphere
Only relevant if 'lithosphere' is set to 1
Default: (use hard-coded default - currently 0.24e25)

0: local lithosphere, equilibrium bedrock depression is found using Archimedes' principle
1: elastic lithosphere, flexural rigidity is taken into account
Only relevant if isostasy = 1
Default: (use hard-coded default - currently 1)

Lithosphere update period (years)
Only relevant if isostasy = 1
Default: (use hard-coded default - currently 100.)

Characteristic time constant of relaxing mantle (years)
Only relevant if isostasy = 1
Default: (use hard-coded default - currently 4000.) 

0: relaxed topography is read from a separate variable
1: first time slice of input topography is assumed to be relaxed
2: first time slice of input topography is assumed to be in isostatic equilibrium with ice thickness
Default: (use hard-coded default - currently 0)

0: not in continuity equation
1: in continuity equation
Default: 1

Determines the treatment of basal water
Only valid for Glide dycore (cism1)
0: Set to zero everywhere
1: Calculated from local water balance
2: Compute the basal water flux, then find depth via calculation
3: Set to constant everywhere (10m), to force T = Tpmp
Default: (use hard-coded default - currently 0)

Basal melt rate for floating ice
0: Basal melt rate = 0 for floating ice
1: Depth-dependent basal melt rate for floating ice as prescribed for MISMIP+
2: Basal melt rate = constant for floating ice (with option to selectively mask out melting)
3: Depth-dependent basal melt rate for floating ice
4: External basal melt rate field (from input file or coupler)
5: [NOT SUPPORTED] Basal melt rate for floating ice from MISOMIP ocean forcing with plume model
Default: 0

0: Calve only at ocean edge
1: Calve wherever the calving criterion is met
Default: 1

0: Do not calve at initialization
1: Calve at initialization
Default: 1

Expert setting.
If true, then cull calving_front cells at initialization.
This can make the run more stable by removing long, thin peninsulas.
If this is set, then also need to set ncull_calving_front.
Default: (use hard-coded default - currently .false.)

How to determine minimum thickness for diagnostic
0: global diagnostics include all cell with H > 0
1: global diagnostics include all cells with H > thklim
This change only affects log files, not output .nc files
Default: (use hard-coded default - currently 1)

Switch units from kg/s to Gt/yr in the log file
0: use kg/s unit in log file
1: use Gt/yr unit in log file
This change only affects log files, not output .nc files
Default: 1

Which dycore to use
0: Glide dycore (SIA, serial only)
1: NOT SUPPORTED: glam dycore (HO, FDM, serial or parallel)
   Note that this option is not allowed within CESM, because it is buggy
2: Glissade dycore (HO, FEM, serial or parallel)
Default: 0 for cism1, 2 for cism2

0: pseudo-diffusion
1: ADI scheme [CANNOT BE USED: RESTARTS ARE NOT EXACT]
2: diffusion
3: remap thickness
4: 1st order upwind
5: no thickness evolution
Options 0, 1 and 2 are for Glide dycore only
Options 3, 4 and 5 are for Glissade dycore only
Default: 0 for cism1, 3 for cism2

0: Constant value, taken from default_flwa
1: Uniform value equal to the Paterson-Budd value at -10 deg C
2: Paterson-Budd temperature-dependent relationship
3: Read flwa/flwastag from file
Default: 2

0: prescribed uniform geothermal heat flux
1: read 2D geothermal flux field from input file, if present
   (if absent, fall back to prescribed uniform geothermal heat flux)
2: calculate geothermal flux using 3d diffusion
Default: 0 for cism1, 1 for cism2

0: no isostasy
1: compute isostasy
Default: 0

If true, then thin marine-based cliffs based on a thickness threshold
Default: .true.

Calving
0: No calving
1: Set thickness to zero if floating
2: Lose a fraction of floating ice at marine margin
3: Set thickness to zero if relaxed bedrock is more than a certain water depth (marine_limit)
4: Set thickness to zero if present bedrock topography lies below a certain water depth (marine_limit)
5: Set thickness to zero based on grid location (field 'calving_mask')
6: Set thickness to zero if ice at marine margin is thinner than a certain value (calving_minthck)
7: Set thickness to zero based on stress (eigencalving) criterion
8: [NOT SUPPORTED] Calve ice that is sufficiently damaged
9: [NOT SUPPORTED] Huybrechts grounding line scheme for Greenland initialization
Default: 1

0: no periodic EW boundary conditions
1: periodic EW boundary conditions
(This is a Glimmer serial option. The parallel code enforces periodic
EW and NS boundary conditions by default.)
Default: (use hard-coded default - currently 0)

If true, then identify and remove icebergs after calving.
These are connected regions with zero basal traction and no connection to grounded ice.
Safer to make it true (and this is needed for stability when allowing floating ice
with more advanced calving options), but not necessary for all applications.
Default: .true.

Restart the model if set to 1. 
This allows for exact restarts from previous initial conditions
Default: 0 for startup or hybrid with CISM_OBSERVED_IC=TRUE, 1 for hybrid/branch with CISM_OBSERVED_IC=FALSE

How to determine sigma values
0: compute standard Glimmer sigma coordinates
1: sigma coordinates are given in external file [NOT ALLOWED WHEN RUNNING CISM IN CESM]
2: read sigma coordinates from config file (from sigma_levels)
3: evenly spaced levels, as required for glam dycore
4: compute Pattyn sigma coordinates
Default: 0

Basal traction parameter
Glide or Glissade local SIA (which_ho_approx = -1) only.
0: no basal sliding
1: constant basal traction coefficient
2: constant coefficient where basal water is present, else no sliding
3: constant coefficient where the basal temperature is at the pressure melting point, else no sliding
4: coefficient is proportional to basal melt rate
5: coefficient is a linear function of basal water depth
Default: 0

Temperature initialization method
0: Initialize temperature to 0 C
1: Initialize temperature to surface air temperature
2: Initialize temperature with a linear profile in each column
3: Initialize temperature with an advective-diffusive balance in each column
4: Initialize temperature from external file
Default: 3 for cism2; 2 for cism1

Determines the temperature solution method
0: isothermal: set column to surface air temperature
1: prognostic temperature solution
2: do NOTHING: hold temperatures steady at initial value
3: prognostic enthalpy solution
Default: 1

Method of integration used to obtain vertical velocity
0: standard vertical integration
1: vertical integration constrained to obey an upper kinematic boundary condition
Default: 0

(m yr-1 Pa-1)
Relevant only when slip_coeff is relevant (Glide or Glissade local SIA)
Default: 1.e-4

(m yr-1 Pa-1)
(Only used for slip_coeff = BTRC_LINEAR_BMLT)
Default: (use hard-coded default - currently 0.)

(Pa-1)
(Only used for slip_coeff = BTRC_LINEAR_BMLT)
Default: (use hard-coded default - currently 0.)

5-element list of values
(Only used for slip_coeff = BTRC_TANH_BWAT)
Default: (use hard-coded default - currently 0.2d0, 0.5d0, 0.0d0 ,1.0d-2, 1.0d0)

Minimum value of beta for grounded ice (Pa yr m-1)
(Applies only to Glissade higher-order dycore)
Default: 100.

Parameter for bmlt_float=3 (depth-dependent basal melt rate for floating ice):
Max freezing rate near surface (m/yr).
(Ignored for other bmlt_float options.)
Default: 0.

Parameter for bmlt_float=3 (depth-dependent basal melt rate for floating ice):
Max melt rate at depth (m/yr).
(Ignored for other bmlt_float options.)
Default: 10.

Parameter for bmlt_float=3 (depth-dependent basal melt rate for floating ice):
Minimum melt rate in warm ocean (m/yr).
Relies on having a warm_ocean_mask field on the input file.
(Ignored for other bmlt_float options.)
Default: 0.

Parameter for bmlt_float=3 (depth-dependent basal melt rate for floating ice):
Depth (m) above which bmlt_float = -frzmax.
(Ignored for other bmlt_float options.)
Default: -100.

Parameter for bmlt_float=3 (depth-dependent basal melt rate for floating ice):
Depth (m) where bmlt_float = 0.
(Ignored for other bmlt_float options.)
Default: -200.

Parameter for bmlt_float=3 (depth-dependent basal melt rate for floating ice):
Depth (m) below which bmlt_float = meltmax.
(Ignored for other bmlt_float options.)
Default: -500.

Parameter for bmlt_float=3 (depth-dependent basal melt rate for floating ice):
Depth (m) above which bmlt_float = meltmin.
Relies on having a warm_ocean_mask field on the input file.
(Ignored for other bmlt_float options.)
Default: 0.

Scale for sub-shelf cavity thickness (m)
Default: 75.

Parameter for local till model: Maximum water depth in till (m)
Relevant only for which_ho_bwat = 2
Default: 2.0

Parameter for local till model: Uniform drainage rate (m/yr)
Relevant only for which_ho_bwat = 2
Default: 1.e-3

Fraction of ice lost to calving (marine_margin = 2 only)
Default: (use hard-coded default - currently 0.2)

Minimum thickness of floating ice at marine edge before it calves (m)
Default: 100.

Timescale for calving (yr) (Glissade only)
calving_thck = thck*max(dt/calving_timescale,1)
If calving_timescale = 0, then the full column calves at once
Default: 0.

Time scale (yr) for limiting marine cliffs (Glissade only)
Default: 0.

Damage rate (1/yr) per unit stress (Pa)
[NOT SUPPORTED]
Default: (use hard-coded default - currently 1.e-7)

Damage threshold for calving
[NOT SUPPORTED]
Default: (use hard-coded default - currently 0.75)

Glen's A to use in isothermal case, i.e, when temperature = 0
Default: (use hard-coded default - currently 1.e-16)

Basal melting range over which N ramps from a small value to full overburden (m/yr)
Relevant only for which_ho_effecpress = 2
Default: (use hard-coded default - currently 1.0d-3)

Parameter for reducing the effective pressure where the bed is warm, saturated or connected to the ocean:
Temperature range over which N ramps from a small value to full overburden (deg C)
Only applies for which_ho_effecpress = 1.
Default: (use hard-coded default - currently 0.1)

Parameter for reducing the effective pressure where the bed is warm, saturated or connected to the ocean:
Multiplier for effective pressure N where the bed is saturated and/or thawed (unitless)
Default: 0.02

Weight that can increase lateral calving rate (eigencalving_constant).
Used only with marine_margin = 7 and 8
Default: (use hard-coded default - currently 1.)

Lateral calving rate (m/yr) per unit stress (Pa)
Used only with marine_margin = 7 and 8
Default: (use hard-coded default - currently 0.01)

Flow enhancement parameter for the Arrhenius relationship;
typically used in SIA model to speed up the ice.
Default: 3.0 for cism1, 1.0 for cism2

Flow enhancement parameter for floating ice.
Default is 1.0, but for marine simulations a smaller value
may be needed to match observed shelf speeds.
Default: 1.0

Constant geothermal heat flux (W m-2; sign convention is positive down)
(May be overwritten by a spatially-varying field in input file [bheatflx])
Default: -0.05

Only relevant for which_ho_babc = 0 
Spatially uniform beta for higher-order dycores (Pa yr m-1)
Default: (use hard-coded default - currently 1000.)

Time scale for basal water to drain (yr-1)
Only relevant for cism1 (Glide dycore)
(Not relevant for basal_water=2)
Default: (use hard-coded default - currently 1000.)

Thickness below which ice dynamics is ignored (m)
Below this limit, ice is only accumulated
Default: 100 for cism1, 1 for cism2

Set to a value between 0 (no messages) and 6 (all messages)
Default: 6

All ice is assumed lost once water depths reach this value (for marine_margin=3 or 4) (m)
Note that water depth is negative
Default: (use hard-coded default - currently -200.)

Maximum surface slope used in the Glissade driving-stress calculation (unitless)
Not valid for other dycores
Default: 0.1

Number of times to cull calving_front cells at initialization
Set to a larger value to remove thicker peninsulas
To use this, also set cull_calving_front to .true.
Default: (use hard-coded default - currently 0)

Optional periodic offset for ismip-hom and similar tests
May be needed to ensure continuous ice geometry at the edges of the
global domain
Default: (use hard-coded default - currently 0.)

Optional periodic offset for ismip-hom and similar tests
May be needed to ensure continuous ice geometry at the edges of the
global domain
Default: (use hard-coded default - currently 0.)

Offset of initial Tbed from pressure melting point temperature (deg C)
Default: 5.

Parameter for pseudo-plasting sliding law:
Bed elevation above which phi = phimax (m)
Default: 700.

Parameter for pseudo-plasting sliding law:
Bed elevation below which phi = phimin (m)
Default: -700.

Parameter for pseudo-plasting sliding law:
max(phi) in pseudo-plastic law, for topg >= bedmin (degrees)
0 < phi < 90
Default: 40.

Parameter for pseudo-plasting sliding law:
min(phi) in pseudo-plastic law, for topg <= bedmin (degrees)
0 < phi < 90
Default: 5.

Parameter for pseudo-plasting sliding law:
Exponent for pseudo-plastic law (unitless)
0 <= q <= 1
q = 1: linear sliding law
q = 0: plastic
Intermediate values: power law
Default: 0.5

Parameter for pseudo-plasting sliding law:
Threshold velocity for pseudo-plastic law (m yr-1)
Default: 100.

Yield stress (Pa) for marine-based ice cliffs (Glissade only)
Default: 1.e6

Thickness scale (in meters) over which gradients increase from zero to full value (HO only)
This parameter does not exist in CISM1 thus CISM2 only.
Default: 50.

List of sigma levels, in ascending order, separated by spaces
These run between 0.0 (at top surface) and 1.0 (at lower surface)
Only relevant if sigma = 2
Default: 0.00 0.15 0.30 0.45 0.60 0.75 0.83 0.90 0.95 0.98 1.00

Adaptively subcycle the advection when advective CFL exceeds this value (Glissade only)
(Zero value means no adaptive subcycling.)
A nonzero value makes it possible for CISM to run with large velocities
that otherwise would violate the advective CFL limit. Results are
generally more accurate and stable, however, if the model is run with a
time step short enough to avoid subcycling.
Default: 0.5 for cism2

Ice sheet timestep (years)
Must translate into an integer number of hours
Default: Depends on resolution and physics option

Diagnostic frequency (years)
Set to 0 for no diagnostic output; set to dt for diagnostic output every time step
Default: Same as dt

x coordinate of point for diagnostic output
Default: resolution-dependent

y coordinate of point for diagnostic output
Default: resolution-dependent

Multiplier of ice sheet timestep, dt
(in theory, can be real-valued, but values less than 1 are not handled properly, so restricted to being an integer)
Default: (use hard-coded default: 1)

Profile period (number of time steps between profiles)
Option for Glide dycore only
Default: 100

Subcycling for Glissade
Default: 1

Space-delimited list of variables output to history file
Default: Depends on physics and ice evolution options

History frequency
e.g., if history_option=nyears, then 1 = annual, 2 = every two years, etc.
Ignored for history_option = 'coupler'
Default: 1

How history frequency is specified
nyears: Write history every N years
coupler: Get history frequency from coupler (HIST_OPTION/HIST_N xml variables)
         WARNING: SHOULD NOT BE USED IN PRODUCTION RUNS - frequency metadata not set properly
Default: nyears

Fractional decrease in glacier area, per day (should be positive).
(days_elapsed * decrease_frac) determines the elevation threshold below which ice_covered is set to 0.
When this factor reaches 1, all elevations below 3500 m are set to non-ice-covered.
Default: 0 (no decrease)

Time delay before beginning decrease_frac overrides (days).
Default: 0 (start overrides at beginning of run)

Whether to enable overrides of the glc fraction sent to the coupler.
If this is false, the other settings in this namelist group are ignored.
ONLY MEANT FOR TESTING - SHOULD NOT BE USED FOR SCIENCE RUNS.
Default: .false.

Fractional increase in glacier area, per day.
(days_elapsed * increase_frac) determines the elevation threshold above which ice_covered is set to 1.
When this factor reaches 1, all elevations >= 0 m are set to ice-covered.
Default: 0 (no increase)

Time delay before beginning increase_frac overrides (days).
Default: 0 (start overrides at beginning of run)

Frequency (days) at which we rearrange elevation classes.
Default: 0 (no flips ever)

Time delay before beginning rearrange_freq overrides (days).
Default: 0 (start overrides at beginning of run)

Whether leap years are enabled in the GLC time manager.
CAUTION: Leap years don't work correctly with GLC time steps longer than a few months.
Default: .false. for NO_LEAP calendar, .true. otherwise

Character to separate date values
Default: '-'

Time step, in units given by dt_option
This generally should not be changed
Default: set based on NCPL_BASE_PERIOD and GLC_NCPL in env_run.xml,
so that there is one GLC time step per coupling period

GLC time-step units
This generally should not be changed
Valid values: steps_per_year, steps_per_day, seconds, hours
Default: set based on NCPL_BASE_PERIOD and GLC_NCPL in env_run.xml,
so that there is one GLC time step per coupling period

Starting day number in month
Default: comes from RUN_STARTDATE or RUN_REFDATE

Starting hour of the day
Default: 0

Starting minute of the day
Default: 0

Starting month number
Default: comes from RUN_STARTDATE or RUN_REFDATE

Starting second of the minute
Default: 0

Starting year number
Default: comes from RUN_STARTDATE or RUN_REFDATE

Simulation identifier (ie case name)
Default: case name set by create_newcase

Stop option -- always let the coupler stop the model so use 'never'.
Default: 'never'