CESM3.0a 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.
               For branch/hybrid runs with CISM_OBSERVED_IC=FALSE, a restart file name
               built based on RUN_REFCASE and RUN_REFDATE.
    

      Whether to enable overrides of the glc fraction sent to the coupler.
      If this is true, then settings in glc_override_nml are used.
      ONLY MEANT FOR TESTING - SHOULD NOT BE USED FOR SCIENCE RUNS.
      Note that, if running with multiple ice sheets, this and the
      various override settings apply to all ice sheets: there is no way
      to do overrides for one ice sheet but not the others.
      Default: .false.
    

      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
    

      List of names of ice sheets in this simulation
      (Determined by scripts -- cannot be set by user)
    

      Number of ice sheets in this simulation
      (Determined by scripts -- cannot be set by user)
    

      Base name of top-level configuration file for CISM
      Actual param file names are this base name plus ".icesheet.config"
      for the given ice sheet.
      (Determined by scripts -- should not 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.
    

      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)
    

      If true, zero out all fluxes sent to the GCM
      Default: Depends on GLC_TWO_WAY_COUPLING xml variable and whether
      this ice sheet is evolving
    

      Uniform initial value of alpha_snow
      Default: 1.0
    

      Max allowed value of alpha_snow (mm/yr w.e/deg C)
      Default: 3.0
    

      Min allowed value of alpha_snow
      Default: 0.3
    

      Baseline date (year CE), when glaciers are assumed to be in balance with climate
      Default: 1984.
    

      Size of incremental adjustment in beta_artm (deg C)
      Default: 0.05
    

      Max allowed magnitude of beta_artm (deg C)
      Default: 5.0
    

      Min ice thickness (m) to be included in glacier area and volume diagnostics
      Diagnostic only; does not enter computations
      Default: 1.0
    

      Factor used to scale dew and dns when scale_area = T
      Typically equal to the cosine of an average latitude
      Default: 1.0
    

      Uniform initial value of mu_star (mm/yr w.e/deg C)
      Default: 1500.
    

      Max allowed value of mu_star (mm/yr w.e/deg C)
      Default: 3000.
    

      Min allowed value of mu_star (mm/yr w.e/deg C)
      Default: 300.
    

      Recent date associated with SMB observations for glaciers out of balance
      Default: 2010.
    

      If true, then redistribute advanced glacier ice in the accumulation zone.
      Minallah et al (GMD 2025) used True for alps
      Default: false
    

      Date of Randolph Glacier Inventory (RGI) observations
      Default: 2003.
    

      If true, then scale the glacier area by cos^2(latitude)
      Default: false
    

      0: apply spatially uniform alpha_snow
      1: invert for glacier-specific alpha_snow
      2: read glacier-specific alpha_snow from external file
      Default: 0
      A value of 1 is appropriate for glacier spin-up, and a value of 2 for forward runs.
    

      0: apply spatially uniform mu_star
      1: invert for glacier-specific mu_star
      2: read glacier-specific mu_star from external file
      Default: 0
      A value of 1 is appropriate for glacier spin-up, and a value of 2 for forward runs.
    

      0: apply spatially uniform powerlaw_c
      1: invert for 2D powerlaw_c
      2: read 2D powerlaw_c from external file
      Default: 0
      A value of 1 is appropriate for glacier spin-up, and a value of 2 for forward runs.
    

      SMB weighting applied to advanced ice in the ablation zone during inversion for mu and alpha
      Should be ~1; could apply a larger value on a fine grid and a smaller value on a coarse grid
      Minallah et al (GMD 2025) used 2.0 on the 100m grid for Alps
      Default: 1.0
    

      0: read the snowfall rate directly
      1: compute the snowfall rate from precip and downscaled artm
      Default: 1
    

      Air temperature (deg C) above which all precip falls as rain
      Applied if snow_calc = 1
      Default: 0.0
    

      Thinning rate for advanced ice in accumulation zone
      Applied if redistribute_advanced_ice = T
      Minallah et al (GMD 2025) used 1.0 for Alps
      Default: 0.0
    

      Spatially uniform temperature threshold for melting (deg C)
      Default: -1.0
    

      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)
      3: No ice at global boundary; scalars set to zero adjacent to boundary
      If running with compute_blocks = 1, only option 3 is supported
      Default: 1 for Greenland, 1 for Antarctica
    

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

      User-specified block sizes, one task per block; optionally, tasks not assigned to inactive blocks
      Would need to be nonzero if running with compute_blocks = 1
      Default: 0
    

      User-specified block sizes, one task per block; optionally, tasks not assigned to inactive blocks
      Would need to be nonzero if running with compute_blocks = 1
      Default: 0
    

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

      Thickness of ocean levels (ISMIP6-style ocean data input);
      nonzero value set in config file
      Default: 0.0 for Greenland, 60. for Antarctica
    

      Number of basins (= 16 for IMBIE2) for ISMIP6-style ocean data input
      Default: 0 for Greenland, 16 for Antarctica
    

      Number of ocean levels fields for ISMIP6-style ocean data input
      Must be a positive integer
      Default: 1 for Greenland, 30 for Antarctica
    

      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.)
    

      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
    

      Flag that indicates whether ice inception away from the main ice sheet is blocked
      Default: true for gris, false for ais
    

      Temperature scale (degC) for transition between thawed and frozen bed
      Default: 0.0
    

      Scale over which N ramps down from overburden to a small value (m)
      Default: 1.0d-3
    

      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
    

      Treatment of opening by melting in cavity-sheet equations
      0: no opening by melting
      1: opening by melting based on bmlt_ground
      2: opening by melting based on dissipation in cavities
      3: opening by melting based on bmlt_ground plus dissipation
      Default: 0
    

      Treatment of opening by sliding in cavity-sheet equations
      0: no opening by sliding
      1: opening by sliding with fixed u_b
      2: opening by sliding with dynamic u_b
      Default: 0
    

      0: Compute on all blocks in the global domain; one task per block
      1: Compute on active blocks only; one task per active block, no task for some or all inactive blocks
      2: Inquire how many active blocks there are, in prep for resubmitting with option 1
      Option 1 can give big computational savings for long spin-ups
      Default: 0
    

      Uniform fixed basal water depth (m)
      Relevant only for which_ho_bwat = 1
      Default: 10.0
    

      If true, the DIVA solver includes a correction for steep slopes
      Default: true
    

      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
    

      Flag that indicates whether coulomb_c depends on elevation
      (coulomb_c_hi for high bed, coulomb_c_lo for low bed, interpolated in between)
      Default: .false.
    

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

      Flux-routing scheme for basal water; applies only if which_ho_bwat = 3
      0: D8; send flux to lowest-elevation neighbor
      1: Dinf; divide flux between two lower-elevation neighbors
      2: FD8; divide flux among all lower-elevation neighbors
      Default: 0
    

      Check the linear solver for convergence every linear_solve_ncheck iterations.
      Default: 10 for Greenland, 10 for Antarctica
    

      Flag that indicates whether peripheral ice caps are removed and added to an ice loss flux
      Default for gris = true, for ais = false
    

      Flag that changes the solver to use code to produce b4b the same solution regardless of
      the number of cores or PE layout.
      Default: true (only for CESM, false in standalone)
    

      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 (DIVA) 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 lateral stress terms are assembled in the glissade finite-element calculation
      0: Standard finite-element calculation of thck and usrf at quadrature points
      1: Apply local cell-center value of thck and usrf on each face
      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: pseudo-plastic basal sliding law; new version with coulomb_c options
      3: pseudo-plastic basal sliding law; old version with tan(phi)
      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: Zoet-Iverson law combining Coulomb and powerlaw behavior
      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 using effective pressure
      14: simple hard-coded pattern (useful for debugging)
      15: treat beta value as a till yield stress (in Pa) using Picard iteration
      Default: 3 for Greenland, 7 for Antarctica
    

      Flag for setting minimum beta beneath grounded ice.
      0: Absolute limit given by beta_grounded_min
      1: Limited using beta_grounded_min, then multiplied by f_ground
      Default: 0 for Greenland, 1 for Antarctica
    

      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
      3: Steady-state water routing with flux calculation
      Default: 2 for Greenland, 0 for Antarctica
    

      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
      Option 1 is required for marine_margin >= 6 (i.e., the subgrid calving laws)
    

      Flag for basal inversion options: invert for Cc = coulomb_c
      Note: Cp inversion is currently supported for which_ho_babc = 7 only (ZI law)
      0: coulomb_c = spatially uniform constant
      1: invert for 2D coulomb_c
      2: read 2D coulomb_c from external file
      3: invert for basin-scale coulomb_c_lo/hi
      4: read basin-scale coulomb_c_lo/hi from external file
      Default: 0 for Greenland, 0 for Antarctica
    

      Flag for ocean temperature corrections
      0: deltaT_ocn = 0 (no corrections)
      1: invert for 2D deltaT_ocn to match thickness target
      2: read deltaT_ocn from external file
      3: invert for basin-scale deltaT_ocn
      4: set deltaT_ocn to match dH/dt target
      Default: 0 for Greenland, 1 for Antarctica
    

      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
      Note: This is independent of setting p_ocean_penetration.
            Setting p > 0 reduces N near grounding line, even when which_ho_effecpress = 0
      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 based on basal water thickness
      3: N depends on cavity opening and closing
      4: N is reduced based on basal water thickness, following Bueler/van Pelt,
      used in CESM2 when using the old pseudoplastic sliding law
      Default: 0 for Greenland, 0 for Antarctica
    

      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
      3: Like (2), but with a correction for topg
      Default: 3
    

      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
    

      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: f_ground = 0 in floating cells (based on flotation condition), else f_ground = 1
      1: basal friction GLP with 0 .lte. f_ground .lte. 1 at vertices
      2: "deluxe" GLP with f_ground at both cells and vertices; includes both friction and melting
      Default: 0
    

      Flag that indicates how to compute bmlt_float in partly grounded cells
      0: Apply bmlt_float in all floating cells, based on floating_mask
      1: Do not apply bmlt_float in partly grounded cells
      2: Set bmlt_float = 0 in partly grounded cells (f_ground > 0)
      Default: 0
    

      Flag that indicates method for solving the nonlinear iteration when solving the first-
      order momentum balance
      0: Use the standard Picard iteration
      1: Do Picard iteration with acceleration
      Default: 1
    

      Flag for basal inversion options: invert for Cp = powerlaw_c
      Note: Cp inversion is currently supported for which_ho_babc = 9, 11 and 12 only
      0: powerlaw_c = spatially uniform constant
      1: invert for 2D powerlaw_c
      2: read 2D powerlaw_c from external file
      3: invert for basin-scale powerlaw_c
      Default: 0 for Greenland, 0 for Antarctica
    

      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
      3: Local tridiagonal preconditioner (one solve per task)
      4: Global tridiagonal preconditioner (global solve)
      Default: 1 for Greenland, 1 for Antarctica
    

      Method for computing velocity solver residual
      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: UNSUPPORTED: standalone interface to Trilinos)
      Default: 3
    

      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: 0 for Greenland, 0 for Antarctica
    

      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)
    

      If true, then adjust thck to maintain usrf, instead of deriving usrf from topg and thck.
      Default: .false. for Greenland, .true. for Antarctica
    

      If true, then apply a calving mask to prevent calving-front advance.
      Default: .false.
    

      Timescale (no. of years) for phasing in artm anomaly forcing
      Default: 0.0
    

      Start date for phasing in artm anomaly forcing
      Default: 0.0
    

      Input method for the surface air temperature
      0: artm(x,y); input as a function of horizontal location only
      1: artm(x,y) + dartm/dz(x,y) * dz; input artm and its vertical gradient
      2: artm(x,y,z); input artm at multiple elevations
      3: artm(x,y) + tlapse * dz; input artm and uniform lapse rate
      Default: 0
    

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

      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
      6: Basal melt rate for floating ice derived from ocean thermal forcing
      Default: 0 for Greenland, 6 for Antarctica
    

      0: lowest forcing magnitude
      1: median forcing magnitude
      2: highest forcing magnitude
    

      0: Quadratic parameterization to compute basal melting from thermal forcing
      1: ISMIP6 local quadratic parameterization to compute basal melting from thermal forcing
      2: ISMIP6 nonlocal quadratic parameterization to compute basal melting from thermal forcing
      3: ISMIP6 nonlocal quadratic parameterization with slope dependence
      Default: 0 for Greenland, 2 for Antarctica
    

      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
    

      Ablation rate as a function of temperature above tmlt (mm/yr w.e./deg C)
      Default: 1000.0
    

      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: NOT SUPPORTED: Glide dycore (SIA, serial only)
         Note that this option is no longer supported in CESM
      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: 2
    

      If true, then use dH/dt during the inversion to match observed melt rates in the forward run.
      Default: .false.
    

      If true, then phase in an air temperature anomaly at the start of the run
      Default: .false.
    

      If true, then phase in a basal melting anomaly at the start of the run
      Default: .false.
    

      If true, then enable CISM glacier calculations;
      Read glacier info at initialization and either spin up or run forward
      Default: .false.
    

      If true, then phase in a precip anomaly at the start of the run
      Default: .false.
    

      If true, then phase in an accumulation/ablation (SMB) anomaly at the start of the run
      Default: .false.
    

      If true, then phase in a snowfall anomaly at the start of the run
      Default: .false.
    

      If true, then phase in a thermal forcing anomaly at the start of the run
      Default: .false.
    

      3: remap thickness
      4: 1st order upwind
      5: no thickness evolution
      Default: 3
    

      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
    

 Flag that indicates whether or not mask SMB outside present-day grid.
      0=no force retreat, 1=force retreat where indicated by retreat_mask,
      2=force retreat for floating ice where indicated by retreat mask
      Default: 0 for Greenland, 0 for Antarctica
    

      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: 1
    

      0: no isostasy
      1: compute isostasy
      Default: 0
    

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

      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: Prescribed advance/retreat rate as in CalvingMIP
      7: Calve ice whose thickness is below a given threshold
      8: Calving rate based on stress threshold criterion
      9: Calving rate based on strain rate (eigencalving) [NOT SUPPORTED]
      10: Stochastic stress-based calving  [NOT SUPPORTED]
      Default: 1 for Greenland, 5 for Antarctica
    

      0: ocean data set internally by CISM
      1: ocean data read from external file
      2: ocean data received from coupler via Glad
      Default: 0 for Greenland, 1 for Antarctica
    

      0: CISM will not extrapolate ocean data into cavities
      1: CISM will extrapolate off-shelf ocean data into shelf cavities
      Default: 0
    

      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 read lat and lon fields from the input file and write to restarts.
      Default: .false.
    

      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.
    

      If true, then identify and remove ice isthmuses after calving.
      These are narrow bridges connecting two regions of floating ice.
      False by default, but may need to be true for the FORCE_RETREAT_FLOATING_ICE option.
      Default: .false. for Greenland, .false. for Antarctica
    

      Restart the model if set to 1.
      If set to 2, restart the model with a reset model time.
      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
    

      Timescale (no. of years) for phasing in smb anomaly forcing
      Default: 0.0
    

      Start date for phasing in smb anomaly forcing
      Default: 0.0
    

      Multiplicative factor for external smb field (unitless)
      Default: 1.0
    

      Input units for the surface mass balance
      0: SMB input in units of m/yr ice (same as acab)
      [removed] 1: SMB input in units of mm/yr water equivalent
      CISM standalone supports different units for smb_input, but this can
      cause unintended side-effects in CESM. See cism_wrapper issue #130
      Default: 0
    

      Input method for the surface mass balance
      0: SMB(x,y); input as a function of horizontal location only
      1: SMB(x,y) + dSMB/dz(x,y) * dz; input SMB and its vertical gradient
      2: SMB(x,y,z); input SMB at multiple elevations
      3: SMB computed with a positive-degree scheme
      Default: 0
    

      Air temperature (deg C) below which all precip falls as snow
      Applied if snow_calc = 1
      Default: 0.0
    

      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
    

      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. for Greenland, 1. for Antarctica
    

      Parameter to limit the min value of beta for various power laws
      Upper limit of ice speed (m/yr) when evaluating powerlaw beta
      Where u > umax, let u = umax when evaluating beta(u).
      Default: 0.0 for Greenland, 5000. for Antarctica
    

      Scale for reducing melting in sub-shelf cavities (m)
      Similar to bmlt_float_h0, which is used specifically for MISMIP+
      Default: 0. for Greenland, 50. for Antarctica
    

      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)
      Used for MISMIP+ tests
      Default: 75.
    

      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.
    

      Bed elevation (m) above which coulomb_c = coulomb_c_hi
      Default: 0.
    

      Bed elevation (m) below which coulomb_c = coulomb_c_lo
      Default: -500.
    

      Parameters for Coulomb friction sliding law (default values from Pimentel et al. 2010)
      Basal stress constant (no dimension)
      Pimentel et al. have coulomb_c = 0.84*m_max, where m_max = coulomb_bump_max_slope
      Default: 0.42
    

      Constant coulomb_c value at high bed elevation, topg >= bed_hi
      Default: 0.5
    

      Constant coulomb_c value at low bed elevation, topg <= bed_lo
      Default: 0.1
    

      Max allowed value for coulomb_c
      Default: 1.0
    

      Min allowed value for coulomb_c
      This value could depend on how effective pressure N is treated;
      min value could be lower if compensating for N being too large
      Default: 0.001
    

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

      Relax the basin correction toward this value
      Default: 0.0
    

      Min value of effective strain (yr^-1) for computation of effective viscosity
      Default: 1.0e-8
    

      Lateral calving rate (m/yr) per unit strain rate (1/yr), in units of m
      [NOT SUPPORTED]
      Used only with marine_margin = 9
    

      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 for Greenland, 0.40 for Antarctica
    

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

      Coefficient for ISMIP6 sub-shelf melt rates (m/yr).
      Default: 0. for Greenland, 25000. for Antarctica
    

      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.
    

      Gravitational acceleration (m/s^2)
      Default: 9.80616
    

      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.)
    

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

      Diffusive length scale (m) for inversion
      Default: 0.0
    

      Relaxation factor (unitless) for C_p or C_c inversion; must be >= 0
      A larger value will help C_p or C_c closer to default values
      Default: 0.05
    

      Ice thickness scale (m) for C_p or C_c inversion; must be > 0.
      Default: 100.
    

      Timescale (yr) for C_p or C_c inversion; must be > 0.
      Note: inversion_babc_timescale is later rescaled to SI units (s).
      Default: 500.
    

      Threshold (m) for counting ice as lightly floating/grounded
      Default: 500.0
    

      Optional mass correction (Gt) for a selected basin
      Default: 1000.0
    

      integer ID for the basin receiving the correction
      Default: 9
    

      Diffusive length scale (m) for inversion
      Default: 0.0
    

      Temperature scale (deg C) for deltaT_ocn inversion, must be >= 0
      Default: 2.0
    

      Thickness scale (m) for deltaT_ocn inversion, must be > 0
      Default: 100.
    

      Timescale (yr) for deltaT_ocn inversion, must be > 0
      Note: inversion_deltaT_ocn_timescale is later rescaled to SI units (s).
      Default: 100.
    

      If usrf_obs implies thck near the flotation thickness,
      set to thck_flotation +/- thck_flotation_buffer (m).
      Default: 2.0
    

      Ice thinner than this threshold (m) is removed at initialization.
      Default: 1.0
    

      Latent heat capacity of ice (J/kg)
      Default: 333700.
    

      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: 0.5
    

      Exponent in Glen's flow law
      Default: 3.0
    

      P-exponent parameter for ocean penetration parameterization (unitless, 0 .le. p .le. 1)
      Default: 0.0
    

      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. for Greenland, 1. for Antarctica
    

      Parameters for power law, taub_b = C * u_b^(1/m); used for babc options 9, 11 and 12
      Friction coefficient in power law, units of Pa m^(-1/3) yr^(1/3)
      Default: 1e4 for Greenland, 2e4 for Antarctica
    

      Parameters for power law, taub_b = C * u_b^(1/m); used for HO_BABC_COULOMB_POWERLAW_TSAI/SCHOOF
      Note: These values work well for MISMIP+, but may not be optimal for whole ice sheets.
      Max value of powerlaw_c, Pa (m/yr)^(-1/3)
      Default: 1.0e+5
    

      Parameters for power law, taub_b = C * u_b^(1/m); used for babc options 9, 11 and 12
      Min value of powerlaw_c, Pa (m/yr)^(-1/3)
      Default: 100. for Greenland, 10. for Antarctica
    

      Parameters for power law, taub_b = C * u_b^(1/m); used for HO_BABC_COULOMB_POWERLAW_TSAI/SCHOOF
      Exponent in power law (unitless)
      Default: 3.0
    

      Parameter for pseudo-plastic sliding law:
      Exponent for pseudo-plastic law (unitless)
      pseudo_plastic_q and pseudo_plastic_u0 apply to which_ho_babc = 2 or 3 only
      0 <= q <= 1
      q = 1: linear sliding law
      q = 0: plastic
      Intermediate values: power law
      Default: 0.5
    

      Parameter for pseudo-plastic sliding law:
      Threshold velocity for pseudo-plastic law (m yr-1)
      Default: 100.
      pseudo_plastic_q and pseudo_plastic_u0 apply to which_ho_babc = 2 or 3 only
    

      Density of ice (kg/m^3)
      Default: 917.0
    

      Density of the ocean (kg/m^3)
      Default: 1026.0
    

      Specific heat capacity of ice (J/kg/K)
      Default: 2117.27
    

      Effective stress threshold for calving (Pa) (Glissade only)
      Used for marine_margin = 8
      Default: 7.5e4
    

      Air temperature lapse rate (deg/m); positive for T decreasing with height
      Default: 0.006
    

      Scalar multiplier for stress eigenvalue 1 (Glissade only)
      Used for marine_margin = 8
      Default: 0.3
    

      Scalar multiplier for stress eigenvalue 2 (Glissade only)
      Used for marine_margin = 8
      Default: 1.0
    

      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)
      Default: 50. for Greenland, 50. for Antarctica
    

      Min value of thermal_forcing_basin (deg C) applied to nonlocal and
      nonlocal-slope schemes
      Default: 0.0
    

      Triple point of water (K)
      Default: 273.16.
    

      Max effective pressure (Pa) for Zoet-Iverson basal friction law
      Default: 1.e8
    

      Threshold velocity (m/yr) for Zoet-Iverson basal friction law
      Default: 200.
    

      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
    

      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
    

      Set dt_option to specify whether the dynamic timestep (model%numerics%tinc)
      is based on dt (the timestep in years) or nsteps_per_year in the config file.
      The default (dt_option = 0) is to read dt directly,
      but the nsteps_per_year option allows more flexibility.
      [0] Input dt in years
      [1] Input dt in steps per year
      Default: 1 (DT_STEPS_PER_YEAR)
    

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

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

      Frequency of writing diagnostic log output, for example:
      0 = never write diagnostic log output
      1 = write after each dynamic time step
      ...
      10 = write every tenth dynamic time step (similarly for other values > 1)
      Default: 0
    

      Number of time steps per year (for dt_input_option=1 (STEPS_PER_YEAR))
      Default: Depends on resolution and physics option
    

      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)
    

      Subcycling for Glissade
      Default: (use hard-coded default: 1)
    

      End time of simulation (yr)
      Not used in CESM coupled runs, but usually needed for standalone
      Default: 1000.0
    

      Start time of simulation (yr)
      Not used in CESM coupled runs, but usually needed for standalone
      Default: 0.0
    

      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)
    

      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'