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Variable Infiltration Capacity (VIC)
Macroscale Hydrologic Model

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VIC Run-Time Options - Global Parameter File

The global parameter file serves two main purposes:

  1. Tells VIC the names, locations, and formats of input and output files
  2. Defines global parameters of the simulation (known as run-time options)

The order of the options in the global parameter file is not important, but the complete option name must be followed by the required option type information. To help in understanding this file, an example file has been attached at the bottom of this page.

Sections of Global Parameter File

  • Define Simulation Parameters
  • Define State Files
  • Define Meteorological Forcing Files
  • Define Parameter Files
  • Define Lake Parameters
  • Define Output Files
  • Example Global Parameter File
  • Other Information

  • Obsolete Options from Earlier Versions
  • Note about compatibility with previous versions of VIC
  • Define Simulation Parameters

    The following options determine the type of simulation that will be performed.

    Main Simulation Parameters

    Name

    Type

    Units

    Description

    NLAYER

    integer

    N/A

    Number of moisture layers used by the model

    NODES

    integer

    N/A

    Number of thermal solution nodes in the soil column

    TIME_STEP

    integer

    hours

    Simulation time step length (must divide 24 evenly). NOTE: TIME_STEP should be < 24 for FULL_ENERGY=TRUE or FROZEN_SOIL=TRUE.

    SNOW_STEP

    integer

    hours

    Length of time step used to solve the snow model (must divide 24 evenly; if TIME_STEP < 24, SNOW_STEP should = TIME_STEP)

    STARTYEAR

    integer

    year

    Year model simulation starts

    STARTMONTH

    integer

    month

    Month model simulation starts

    STARTDAY

    integer

    day

    Day model simulation starts

    STARTHOUR

    integer

    hour

    Hour model simulation starts

    EITHER:

     

     

    Note: either NRECS or ENDYEAR, ENDMONTH, and ENDDAY must be specified, but not both

          NRECS

    integer

    N/A

    Number of time steps over which to run model. NOTE: The number of records must be defined such that the model completes the last day.

    OR:

     

     

    Note: either NRECS or ENDYEAR, ENDMONTH, and ENDDAY must be specified, but not both

          ENDYEAR

    integer

    year

    Year model simulation ends

          ENDMONTH

    integer

    month

    Month model simulation ends

          ENDDAY

    integer

    day

    Day model simulation ends

    Define Energy Balance Parameters

    The following options determine the method of resolving the surface energy balance.

    Name

    Type

    Units

    Description

    FULL_ENERGY

    string

    TRUE or FALSE

    Option for computing land surface temperature (soil or snowpack surface)

    • TRUE = compute (via iteration) the temperature that balances the surface energy budget
    • FALSE = set surface temperature equal to air temperature

    Default = FALSE.

    CLOSE_ENERGY

    string

    TRUE or FALSE

    Option for controlling links between the energy balances of the surface and the canopy

    • TRUE = iterate between the canopy and surface energy balances until they are consistent
    • FALSE = compute the surface and canopy energy balances separately, once per time step

    Default = FALSE.

    Define Soil Temperature Parameters

    The following options determine the type of simulation that will be performed.

    Name

    Type

    Units

    Description

    FROZEN_SOIL

    string

    TRUE or FALSE

    Option for handling the water/ice phase change in frozen soils

    • TRUE = account for water/ice phase change (including latent heat)
    • FALSE = soil moisture always remains liquid, even when below 0 C; no latent heat effects and ice content is always 0.

    Default = FALSE.

    Note: to activate this option, the user must also set the FS_ACTIVE flag to 1 in the soil parameter file for each grid cell where this option is desired. In other words, the user can choose for some grid cells (e.g. cold ones) to compute ice contents and for others (e.g. warm ones) to skip the extra computation.

    QUICK_FLUX

    string

    TRUE or FALSE

    Option for computing the soil vertical temperature profile

    • TRUE = use the approximate method described by Liang et al. (1999) to compute soil temperatures and ground heat flux; this method ignores water/ice phase changes
    • FALSE = use the finite element method described in Cherkauer and Lettenmaier (1999) to compute soil temperatures and ground heat flux; this method is appropriate for accounting for water/ice phase changes

    Default = FALSE (i.e. use Cherkauer and Lettenmaier (1999)) when running FROZEN_SOIL; and TRUE (i.e. use Liang et al. (1999)) in all other cases.

    IMPLICIT

    string

    TRUE or FALSE

    If TRUE the model will use an implicit solution for the soil heat flux equation of Cherkauer and Lettenmaier (1999) (QUICK_FLUX is FALSE), otherwise uses original explicit solution. When QUICK_FLUX is TRUE the implicit solution has no effect.

    The user can override this option by setting IMPLICIT to FALSE in the global parameter file. The implicit solution is guaranteed to be stable for all combinations of time step and thermal node spacing; the explicit solution is only stable for some combinations. If the user sets IMPLICIT to FALSE, VIC will check the time step, node spacing, and soil thermal properties to confirm stability. If the explicit solution will not be stable, VIC will exit with an error message.

    Default = TRUE.

    QUICK_SOLVE

    string

    TRUE or FALSE

    This option is a hybrid of QUICK_FLUX TRUE and FALSE. If TRUE model will use the method described by Liang et al. (1999) to compute ground heat flux during the surface energy balance iterations, and then will use the method described in Cherkauer and Lettenmaier (1999) for the final solution step.

    Default = FALSE.

    NOFLUX

    string

    TRUE or FALSE

    If TRUE model will use a no flux bottom boundary with the finite difference soil thermal solution (i.e. QUICK_FLUX = FALSE or FULL_ENERGY = TRUE or FROZEN_SOIL = TRUE).

    Default = FALSE (i.e., use a constant temperature bottom boundary condition).

    EXP_TRANS

    string

    TRUE or FALSE

    If TRUE the model will exponentially distributes the thermal nodes in the Cherkauer and Lettenmaier (1999) finite difference algorithm, otherwise uses linear distribution. (This is only used if FROZEN_SOIL = TRUE).

    Default = TRUE.

    GRND_FLUX_TYPE

    string

    N/A

    Options for handling ground flux:

    • GF_406 = use (flawed) formulas for ground flux, deltaH, and fusion as in VIC 4.0.6 and earlier
    • GF_410 = use formulas from VIC 4.1.0

    NOTE: this option exists for backwards compatibility with earlier releases and likely will be removed in later releases.

    Default = GF_410.

    TFALLBACK

    string

    TRUE or FALSE

    Options for handling failures of T iterations to converge:

    • FALSE = if T iteration fails to converge, report an error
    • TRUE = if T iteration fails to converge, use the previous time step's T value

    This option affects the temperatures of canopy air, canopy snow, ground snow pack, ground surface, and soil T nodes. If TFALLBACK is TRUE, VIC will report the total number of instances in which the previous step's T was used, at the end of each grid cell's simulation.

    In addition, a time series of when these instances occurred (averaged across all veg tile/snow band combinations) can be written to the output files, using the following output variables:

    • OUT_TFOL_FBFLAG = time series of T fallbacks in canopy snow T solution
    • OUT_TCAN_FBFLAG = time series of T fallbacks in canopy air T solution
    • OUT_SNOWT_FBFLAG = time series of T fallbacks in snow pack surface T solution
    • OUT_SURFT_FBFLAG = time series of T fallbacks in ground surface T solution
    • OUT_SOILT_FBFLAG = time series of T fallbacks in soil node T solution (one time series per node)

    Default = TRUE.

    SPATIAL_FROST

    string

    (+integer)

    string: TRUE or FALSE

    integer: N/A

    Option to allow spatial heterogeneity in soil temperature:

    • FALSE = Assume soil temperature is horizontally constant (only varies with depth)
    • TRUE = Assume soil temperatures at each given depth are distributed horizontally with a uniform (linear) distribution, so that even when the mean temperature is below freezing, some portion of the soil within the grid cell at that depth could potentially be above freezing. This requires specifying a frost slope value as an extra field in the soil parameter file, so that the minimum/maximum temperatures can be computed from the mean value. The maximum and minimum temperatures will be set to mean temperature +/- frost_slope.
    • If TRUE is specified, you must follow this with an integer value for Nfrost, the number of frost sub-areas (each having a distinct temperature)

    Default = FALSE.

    Precipitation (Rain and Snow) Parameters

    Generally these default values do not need to be overridden.

    Name

    Type

    Units

    Description

    SNOW_DENSITY

    string

    N/A

    Options for computing snow density:

    • DENS_BRAS = Use traditional VIC algorithm taken from Bras, 1990.
    • DENS_SNTHRM = Use algorithm taken from SNTHRM model.

    Default = DENS_BRAS.

    BLOWING

    string

    TRUE or FALSE

    If TRUE, compute evaporative fluxes due to blowing snow

    Default = FALSE.

    COMPUTE_TREELINE

    string or integer

    FALSE or veg class id

    Options for handling above-treeline vegetation:

    • FALSE = Do not compute treeline or replace vegetation above the treeline.
    • CLASS_ID = Compute the treeline elevation based on average July temperatures; for those elevation bands with elevations above the treeline (or the entire grid cell if SNOW_BAND == 1 and the grid cell elevation is above the tree line), if they contain vegetation tiles having overstory, replace that vegetation with the vegetation having id CLASS_ID in the vegetation library.

    NOTE: You MUST supply VIC with a July average air temperature, in the optional July_Tavg field, AND set the JULY_TAVG_SUPPLIED option to TRUE so that VIC can read the soil parameter file correctly.

    NOTE: If LAKES=TRUE, COMPUTE_TREELINE MUST be FALSE.

    Default = FALSE.

    CORRPREC

    string

    TRUE or FALSE

    If TRUE correct precipitation for gauge undercatch
    NOTE: This option is not supported when using snow/elevation bands.

    Default = FALSE.

    MAX_SNOW_TEMP

    float

    deg C

    Maximum temperature at which snow can fall

    Default = 0.5 C.

    MIN_RAIN_TEMP

    float

    deg C

    Minimum temperature at which rain can fall

    Default = -0.5 C.

    SPATIAL_SNOW

    string

    TRUE or FALSE

    Option to allow spatial heterogeneity in snow water equivalent (yielding partial snow coverage) when the snow pack is melting:

    • FALSE = Assume snow water equivalent is constant across grid cell
    • TRUE = Assume snow water equivalent is distributed horizontally with a uniform (linear) distribution, so that some portion of the grid cell has 0 snow pack. This requires specifying the max_snow_distrib_slope value as an extra field in the soil parameter file.

    NOTE: max_snow_distrib_slope should be set to twice the desired minimum spatial average snow pack depth [m]. I.e., if we define depth_thresh to be the minimum spatial average snow depth below which coverage < 1.0, then max_snow_distrib_slope = 2*depth_thresh.

    NOTE: Partial snow coverage is only computed when the snow pack has started melting and the spatial average snow pack depth <= max_snow_distrib_slope/2. During the accumulation season, coverage is 1.0. Even after the pack has started melting and depth <= max_snow_distrib_slope/2, new snowfall resets coverage to 1.0, and the previous partial coverage is stored. Coverage remains at 1.0 until the new snow has melted away, at which point the previous partial coverage is recovered.

    Default = FALSE.

    Turbulent Flux Parameters

    Generally these default values do not need to be overridden.

    Name

    Type

    Units

    Description

    MIN_WIND_SPEED

    float

    m/s

    Minimum allowable wind speed.

    Default = 0.1 m/s.

    AERO_RESIST_CANSNOW

    string

    N/A

    Options for aerodynamic resistance in snow-filled canopy:

    • AR_406 = Multiply by 10 for latent heat, but do NOT multiply by 10 for sensible heat. When no snow in canopy, use surface aero_resist instead of overstory aero_resist. (As in VIC 4.0.6).
    • AR_406_LS = Multiply by 10 for both latent and sensible heat. When no snow in canopy, use surface aero_resist instead of overstory aero_resist.
    • AR_406_FULL = Multiply by 10 for both latent and sensible heat. Always use overstory aero_resist (snow or bare).
    • AR_410 = Apply stability correction, instead of multiplying by 10, for both latent and sensible heat. Always use overstory aero_resist (snow or bare).

    NOTE: this option exists for backwards compatibility with earlier releases and likely will be removed in later releases.

    Default = AR_406_FULL.

    Meteorological Forcing Disaggregation Parameters

    Generally these default values do not need to be overridden.

    Name

    Type

    Units

    Description

    OUTPUT_FORCE

    string

    TRUE or FALSE

    Option to save VIC's internal, disaggregated forcings:

    • FALSE = Run a simulation (including disaggregating the forcings).
    • TRUE = Do not run a simulation; simply disaggregate the forcings and write them to output files. This allows us to use VIC as a meteorological forcing disaggregator. Note that in this mode of operation, VIC should be executed the same way as normal: VIC still must read a global parameter file that tells it the locations of the forcings and soil parameter file, and sets the model time step (this is the time step the forcings will be disaggregated to), the output time step (usually the same as the model time step in this case), and start/end dates.

    Default = FALSE.

    PLAPSE

    string

    TRUE or FALSE

    Options for computing grid cell average surface atmospheric pressure (and density) when it is not explicitly supplied as a meteorological forcing:

    • FALSE = Set surface atmospheric pressure to constant 95.5 kPa (as in earlier releases).
    • TRUE = Lapse surface atmospheric pressure (and density) from sea level to the grid cell average elevation.

    NOTE: air pressure is already lapsed to grid cell or band elevation when computing latent heat; this option only affects computation of sensible heat.

    NOTE: this option exists for backwards compatibility with earlier releases and likely will be removed in later releases (the TRUE option will become the standard behavior).

    Default = TRUE.

    SW_PREC_THRESH

    float

    mm

    Minimum daily precipitation, above which incoming shortwave is dimmed by 25%, when shortwave is not supplied as a forcing but instead is estimated from daily temperature range.

    This option's purpose is to avoid erroneous dimming of estimated shortwave when using forcings that have been aggregated or re-sampled from a different resolution. Re-sampling can sometimes smear small amounts of precipitation from neighboring cells into cells that originally had no precipitation. The appropriate value of SW_PREC_THRESH must be found through examination of the forcings.

    Default = 0 mm (any precipitation causes dimming)

    MTCLIM_SWE_CORR

    string

    TRUE or FALSE

    This controls VIC's estimates of incoming shortwave (when shortwave is not supplied as a forcing) in the presence of snow. When shortwave is supplied as a forcing, this option is ignored.

    • TRUE = Adjust incoming shortwave for snow albedo effect.
    • FALSE = Do not adjust shortwave (as in earlier releases).

    Default = TRUE.

    VP_ITER

    string

    N/A

    This controls VIC's iteration between estimates of shortwave and vapor pressure:

    • VP_ITER_NEVER = Never iterate; make estimates separately.
    • VP_ITER_ALWAYS = Always iterate once (as in previous releases).
    • VP_ITER_ANNUAL = Iterate once for arid climates (based on annual Precip/PET ratio) and never for humid climates.
    • VP_ITER_CONVERGE = Always iterate until shortwave and vp stabilize.

    Default = VP_ITER_ALWAYS.

    VP_INTERP

    string

    TRUE or FALSE

    This controls sub-daily humidity estimates:

    • TRUE = Interpolate daily VP estimates linearly between sunrise of one day to the next.
    • FALSE = Hold VP constant for entire day (as in previous releases).

    Default = TRUE.

    LW_TYPE

    string

    N/A

    This controls the algorithm used to estimate clear-sky longwave radiation:

    • LW_TVA = Tennessee Valley Authority algorithm (1972) (this option is what previous releases used)
    • LW_ANDERSON = Algorithm of Anderson (1964)
    • LW_BRUTSAERT = Algorithm of Brutsaert (1975)
    • LW_SATTERLUND = Algorithm of Satterlund (1979)
    • LW_IDSO = Algorithm of Idso (1981)
    • LW_PRATA = Algorithm of Prata (1996)

    Default = LW_TVA.

    LW_CLOUD

    string

    N/A

    This controls the algorithm used to estimate the influence of clouds on total longwave:

    • LW_CLOUD_BRAS = Method from Bras textbook (this option is what previous releases used)
    • LW_CLOUD_DEARDORFF = Algorithm of Deardorff (1978)

    Default = LW_CLOUD_DEARDORFF.

    Carbon Parameters

    The following options only apply to carbon cycling.

    Name

    Type

    Units

    Description

    CARBON

    string

    TRUE or FALSE

    Options for handling carbon cycle:

    • FALSE = do not simulate carbon cycle
    • TRUE = simulate carbon cycle

    Default = FALSE.

    RC_MODE

    string

    RC_JARVIS or RC_PHOTO

    Determines how canopy resistance is computed

    Options for RC_MODE:

    • RC_JARVIS = VIC computes canopy resistance by applying resistance factors to the veg class's minimum canopy resistance listed in the veg library file.
    • RC_PHOTO = VIC computes canopy resistance by applying resistance factors to the canopy resistance corresponding to photosynthetic demand (in the absence of moisture limitation).

    Default = RC_JARVIS.

    VEGLIB_PHOTO

    TRUE or FALSE

    string

    Tells VIC about the contents of the veg library file

    Options for VEGLIB_PHOTO:

    • FALSE = veg library file does not contain photosynthesis parameters.
    • TRUE = veg library file contains photosynthesis parameters.

    Default = FALSE

    Miscellaneous Parameters

    Generally these default values do not need to be overridden.

    Name

    Type

    Units

    Description

    CONTINUEONERROR

    string

    TRUE or FALSE

    Options for handling fatal errors:

    • FALSE = if simulation of a grid cell encounters an error, exit VIC
    • TRUE = if simulation of a grid cell encounters an error, move to next grid cell

    NOTE: in either case, if a grid cell encounters a fatal error, the output files for that grid cell will likely be incomplete. But since most fatal errors are the result of failure of the temperature iteration to converge, seting the TFALLBACK option to TRUE should eliminate most fatal errors. See the section on Soil Temperature Options for more information.

    Default = TRUE.


    Define State Files

    The following options control input and output of state files.

    Name

    Type

    Units

    Description

    INIT_STATE

    string

    path/filename

    Full path and filename of initial state file.

    NOTE: if INIT_STATE is not specified, VIC will take initial soil moistures from the soil parameter file and set all other state variables to a default state.

    STATENAME

    string

    path/filename

    Path and file prefix of the state file to be created on the specified date. The date within the simulation at which the state is saved will be appended to the file prefix to form a complete file name.

    NOTE: if STATENAME is not specified, VIC will not save its state in a statefile.

    STATEYEAR

    integer

    year

    Year at which model simulation state should be saved.

    NOTE: if STATENAME is not specified, STATEYEAR will be ignored.

    STATEMONTH

    integer

    month

    Month at which model simulation state should be saved.

    NOTE: if STATENAME is not specified, STATEMONTH will be ignored.

    STATEDAY

    integer

    day

    Day at which model simulation state should be saved. State will be saved at the end of the final timestep on this day.

    NOTE: if STATENAME is not specified, STATEDAY will be ignored.

    BINARY_STATE_FILE

    string

    TRUE or FALSE

    If FALSE, VIC reads/writes the intial/output state files in ASCII format. If TRUE, VIC reads/writes intial/output state files in binary format.

    NOTE: if INIT_STATE or STATENAME are not specified, BINARY_STATE_FILE will be ignored.


    Define Meteorological Forcing Files

    This section describes how to define the forcing files needed by the VIC model.

    Unlike model parameters, for which 1 file contains data for all grid cells, the meteorological forcings are stored as a separate time series for each grid cell. If the input forcings are daily and VIC is running with a sub-daily model timestep, it will disaggregate the daily forcings to sub-daily, using the "mtclim" algorithm of Thornton and Running (ref?). However, VIC will not disaggregate sub-daily forcings from one time step length to another. If the input forcings are sub-daily, and VIC is running with a different sub-daily model timesetep, VIC will exit. Input files can be ASCII or Binary (signed or unsigned short ints) column formatted. Columns in the file must be in the same order as they are defined in the global control file.

    VIC will allow forcing data to be stored in two different files per grid cell (e.g., precip and wind speed in one file, tmin and tmax in another file). Note that if you are using two forcing files per grid cell, the parameters for the first file must be defined before those for the second. Bold numbers indicate the order in which these values should be defined, after each forcing file (FORCING1 or FORCING2). Options that do not have a bold number apply to both forcing file types and should appear after the numbered options.

    All FORCING filenames are actually the pathname, and prefix for gridded data types: ex. DATA/forcing_YY.YYY_XX.XXX. Latitude and longitude index suffix is added by VIC based on GRID_DECIMAL parameter defined above, and the latitude and longitude values defined in the soil parameter file.

    Name

    Type

    Units

    Description

    (1*) FORCING1

    string

    pathname and file prefix

    First forcing file name, always required. This must precede all other forcing parameters used to define the first forcing file.

    (1*) FORCING2

    string

    pathname and file prefix

    Second forcing file name, or FALSE if only one file used. This must precede all other forcing parameters used to define the second forcing file, and follow those used to define the first forcing file.

    (2) FORCE_FORMAT

    string

    BINARY or ASCII

    Defines the format type for the forcing files.

    (3)FORCE_ENDIAN

    string

    BIG or LITTLE

    Identifies the architecture of the machine on which the binary forcing files were created:

    • BIG = big-endian (e.g. SUN)
    • LITTLE = little-endian (e.g. PC/linux)

    Model will identify the endian of the current machine, and swap bytes if necessary. Required for binary forcing file, not used for ASCII forcing file.

    (4) N_TYPES

    int

    N/A

    Number of columns in the current data file.

    (5) FORCE_TYPE

    string
    string
    float

    VarName
    (un)signed
    multiplier

    Defines what forcing types are read from the file, and in what order. For ASCII file only the forcing type needs to be defined, but for Binary file each line must also define whether the column is SIGNED or UNSIGNED short int and by what factor values are multiplied before being written to output. Click here for details.

    (6) FORCE_DT

    integer

    hours

    Time step length of the current input files in hours

    (7) FORCEYEAR

    integer

    year

    Year meteorological forcing files start

    (8) FORCEMONTH

    integer

    month

    Month meteorological forcing files start

    (9) FORCEDAY

    integer

    day

    Day meteorological forcing files start

    (10) FORCEHOUR

    integer

    hour

    Hour meteorological forcing files start

    GRID_DECIMAL

    integer

    N/A

    Number of decimals to use in gridded file name extensions

    WIND_H

    float

    m

    Height of wind speed measurement over bare soil and snow cover. Wind measurement height over vegetation is now read from the vegetation library file for all types, the value in the global file only controls the wind height over bare soil and over the snow pack when a vegetation canopy is not defined.

    MEASURE_H

    float

    m

    Height of humidity measurement

    ALMA_INPUT

    string

    TRUE or FALSE

    This option tells VIC the units to expect for the input variables:

    • FALSE = Use standard VIC units: for moisture fluxes, use cumulative mm over the time step; for temperature, use degrees C;
    • TRUE = Use the units of the ALMA convention: for moisture fluxes, use the average rate in mm/s (or kg/m^2s) over the time step; for temperature, use degrees K;

    Default = FALSE.

    * If using one forcing file, use only FORCING1, if using two forcing files, define all parameters for FORCING1, and then define all forcing parameters for FORCING2. All parameters need to be defined for both forcing files when a second file is used.

    Examples. a standard four column daily forcing data file will be defined as:

    ASCII File

    FORCING1	FORCING_DATA/LDAS_ONE_DEGREE/data_
    N_TYPES		4
    FORCE_TYPE	PREC
    FORCE_TYPE	TMAX
    FORCE_TYPE	TMIN
    FORCE_TYPE	WIND
    FORCE_FORMAT	ASCII
    FORCE_DT	24
    

    Binary File

    FORCING1	FORCING_DATA/LDAS_ONE_DEGREE/data_
    N_TYPES		4
    FORCE_TYPE	PREC	UNSIGNED	40
    FORCE_TYPE	TMAX	SIGNED		100
    FORCE_TYPE	TMIN	SIGNED		100
    FORCE_TYPE	WIND	SIGNED		100
    FORCE_FORMAT	BINARY
    FORCE_ENDIAN	LITTLE
    FORCE_DT	24
    

    Define Parameter Files

    The following options describe the input parameter files.

    Name

    Type

    Units

    Description

    SOIL

    string

    path/filename

    the Soil parameter file.

    BASEFLOW

    string

    N/A

    This option describes the form of the baseflow parameters in the soil parameter file:

    • ARNO = fields 5-8 of the soil parameter file are the standard VIC baseflow parameters
    • NIJSSEN2001 = fields 5-8 of the soil parameter file are the baseflow parameters from Nijssen et al (2001)

    Default = ARNO.

    JULY_TAVG_SUPPLIED

    string

    TRUE or FALSE

    If TRUE then VIC will expect an additional column (July_Tavg) in the soil parameter file to contain the grid cell's average July temperature. If your soil parameter file contains this optional column, you MUST set JULY_TAVG_SUPPLIED to TRUE so that VIC can read the soil parameter file correctly.

    NOTE: Supplying July average temperature is only required if the COMPUTE_TREELINE option is set to TRUE.

    Default = FALSE.

    ORGANIC_FRACT

    string

    TRUE or FALSE

    (release 4.1.2 and later)

    TRUE = the soil parameter file contains 3*Nlayer extra columns, listing, for each layer: the organic fraction, and the bulk density and soil particle density of the organic matter in the soil layer.

    FALSE = the soil parameter file does not contain any information about organic soil, and organic fraction should be assumed to be 0.

    Default = FALSE.

    VEGLIB

    string

    path/filename

    Vegetation library file name

    VEGPARAM

    string

    path/filename

    Vegetation parameter file name

    ROOT_ZONES

    integer

    N/A

    Number of defined root zones defined for root distribution.

    VEGPARAM_ALBEDO

    string

    TRUE or FALSE

    If TRUE the vegetation parameter file contains an extra line for each vegetation type that defines monthly ALBEDO values for each vegetation type for each grid cell.

    Default = FALSE.

    ALBEDO_SRC

    string

    N/A

    This option tells VIC where to look for ALBEDO values:

    • FROM_VEGLIB = Use the ALBEDO values listed in the vegetation library file.
    • FROM_VEGPARAM = Use the ALBEDO values listed in the vegetation parameter file. Note: for this to work, VEGPARAM_ALBEDO must be TRUE.

    Default = FROM_VEGLIB.

    VEGPARAM_LAI

    string

    TRUE or FALSE

    If TRUE the vegetation parameter file contains an extra line for each vegetation type that defines monthly LAI values for each vegetation type for each grid cell.

    Default = FALSE.

    LAI_SRC

    string

    N/A

    This option tells VIC where to look for LAI values:

    • FROM_VEGLIB = Use the LAI values listed in the vegetation library file.
    • FROM_VEGPARAM = Use the LAI values listed in the vegetation parameter file. Note: for this to work, VEGPARAM_LAI must be TRUE.

    Default = FROM_VEGLIB.

    VEGLIB_VEGCOVER

    string

    TRUE or FALSE

    If TRUE the vegetation library file contains monthly VEGCOVER values for each vegetation type for each grid cell (between the LAI and ALBEDO values).

    Default = FALSE.

    VEGPARAM_VEGCOVER

    string

    TRUE or FALSE

    If TRUE the vegetation parameter file contains an extra line for each vegetation type that defines monthly VEGCOVER values for each vegetation type for each grid cell.

    Default = FALSE.

    VEGCOVER_SRC

    string

    N/A

    This option tells VIC where to look for VEGCOVER values:

    • FROM_VEGLIB = Use the VEGCOVER values listed in the vegetation library file. Note: for this to work, VEGLIB_VEGCOVER must be TRUE..
    • FROM_VEGPARAM = Use the VEGCOVER values listed in the vegetation parameter file. Note: for this to work, VEGPARAM_VEGCOVER must be TRUE.

    Default = FROM_VEGLIB.

    SNOW_BAND

    integer
    string

    N/A
    path/filename

    Maximum number of snow elevation bands to use, and the name (with path) of the snow elevation band file. For example:

    • SNOW_BAND 5 path/filename

    To turn off this feature, set the number of snow bands to 1 and do not follow this with a snow elevation band file name.

    Default = 1.


    Lake Parameters

    The following options only take effect when the lake model is running.

    Name

    Type

    Units

    Description

    LAKES

    string

    FALSE or path/filename

    Options for handling lakes:

    • FALSE = do not simulate lakes
    • lake parameter path/filename = simulate lakes and read the given file for lake model parameters

    Default = FALSE.

    LAKE_PROFILE

    string

    TRUE or FALSE

    Options for describing lake profile:

    • FALSE = VIC computes a parabolic depth-area profile for the lake basin
    • TRUE = VIC reads user-specified depth-area profile from the lake parameter file

    Default = FALSE.

    EQUAL_AREA

    string

    TRUE or FALSE

    Options for computing grid cell areas:

    • FALSE = Grid cell boundaries and centers fall on a regular lat-lon grid, i.e. grid cells appear as squares when plotted in geographic projection; this means that the grid cells do not have equal areas.
    • TRUE = Grid cells have equal area, i.e. they appear as squares when plotted in an equal-area projection; this means that their boundaries do not fall on a regular lat-lon grid and the cell centers are not equally-spaced in latitude and longitude.

    Default = FALSE.

    RESOLUTION

    float

    decimal degrees of latitude or area in km^2

    Options for grid cell resolution:

    • If EQUAL_AREA = FALSE: width of grid cells, in decimal degrees latitude or longitude.
    • If EQUAL_AREA = TRUE: area of grid cells, in km^2.

    Default = none; this MUST be set by the user to match the grid cell size if the lake model is running.


    Define Output Files

    The following options describe the output files. Click here for more information.

    Name

    Type

    Units

    Description

    RESULT_DIR

    string

    path name

    Name of directory where model results are written

    OUT_STEP

    integer

    hours

    Output time step length

    SKIPYEAR

    integer

    years

    Number of years to skip before starting to write output file. Used to reduce output by not including spin-up years.

    COMPRESS

    string

    TRUE or FALSE

    if TRUE compress input and output files when done (uses gzip)

    BINARY_OUTPUT

    string

    TRUE or FALSE

    If TRUE write output files in binary (default is ASCII).

    ALMA_OUTPUT

    string

    TRUE or FALSE

    Options for output units:

    • FALSE = standard VIC units. Moisture fluxes are in cumulative mm over the time step; temperatures are in degrees C
    • TRUE = units follow the ALMA convention. Moisture fluxes are in average mm/s (kg/m^2s) over the time step; temperatures are in degrees K

    Default = FALSE.

    Click here for more information.

    MOISTFRACT

    string

    TRUE or FALSE

    Options for output soil moisture units (default is FALSE):

    • FALSE = Standard VIC units. Soil moisture is in mm over the grid cell area
    • TRUE = Soil moisture is volume fraction

    PRT_HEADER

    string

    TRUE or FALSE

    Options for output file headers (default is FALSE):

    • FALSE = output files contain no headers
    • TRUE = headers are inserted into the beginning of each output file, listing the names of the variables in each field of the file (if ASCII) and/or the variable data types (if BINARY)

    Click here for more information.

    PRT_SNOW_BAND

    string

    TRUE or FALSE

    if TRUE then print snow variables for each snow band in a separate output file (snow_band_*).

    NOTE: this option is ignored if output file contents are specified.

    N_OUTFILES, OUTFILE, and OUTVAR are optional; if omitted, traditional output files are produced. Click here for details on using these instructions.

    N_OUTFILES

    integer

    N/A

    Number of output files per grid cell. Click here for more information.

    OUTFILE

    string
    integer

    prefix
    nvars

    Information about this output file:

    1. Prefix of the output file (to which the lat and lon will be appended)
    2. Number of variables in the output file

    This should be specified once for each output file. Click here for more information.

    OUTVAR

    string
    string
    string
    integer

    name
    format
    type
    multiplier

    Information about this output variable:

    1. Name (must match a name listed in vicNl_def.h)
    2. Output format (C fprintf-style format code)
    3. Data type (one of: OUT_TYPE_DEFAULT, OUT_TYPE_CHAR, OUT_TYPE_SINT, OUT_TYPE_USINT, OUT_TYPE_INT, OUT_TYPE_FLOAT,OUT_TYPE_DOUBLE)
    4. Multiplier - number to multiply the data with in order to recover the original values (only valid with BINARY_OUTPUT=TRUE)

    This should be specified once for each output variable. Click here for more information.


    Obsolete Options from Earlier Versions

    The following options are no longer supported.

    Name

    Type

    Units

    Description

    GRND_FLUX

    string

    TRUE or FALSE

    Versions 4.1.1 and earlier.

    If TRUE, compute ground heat flux and energy balance; if FALSE, do not compute ground heat flux. Default: If FULL_ENERGY or FROZEN_SOIL are TRUE, GRND_FLUX is automatically set to TRUE; otherwise GRND_FLUX is automatically set to FALSE.

    MIN_LIQ

    string

    TRUE or FALSE

    Version 4.1.1 only.

    Options for handling minimum soil moisture in presence of ice (default is FALSE):

    • FALSE = Use residual moisture as lower bound on soil moisture in Brooks-Corey/Campbell and other relationships involving liquid water.
    • TRUE = Use (residual moisture * unfrozen water fraction as function of temperature) as lower bound on soil moisture in Brooks-Corey/Campbell and other relationships involving liquid water.

    GLOBAL_LAI

    string

    TRUE or FALSE

    If TRUE the vegetation parameter file contains an extra line for each vegetation type that defines monthly LAI values for each vegetation type for each grid cell.

    NOTE: This option has been replaced by the two options LAI_SRC and VEGPARAM_LAI.

    PRT_FLUX

    string

    TRUE or FALSE

    Versions 4.1.1 and earlier.

    if TRUE print energy fluxes debugging files

    PRT_BALANCE

    string

    TRUE or FALSE

    Versions 4.1.1 and earlier.

    if TRUE print water balance debugging files

    PRT_SOIL

    string

    TRUE or FALSE

    Versions 4.1.1 and earlier.

    if TRUE print soil parameter debugging files

    PRT_VEGE

    string

    TRUE or FALSE

    Versions 4.1.1 and earlier.

    if TRUE print vegetation parameter debugging files

    PRT_GLOBAL

    string

    TRUE or FALSE

    Versions 4.1.1 and earlier.

    if TRUE print global parameter debugging files

    PRT_ATMOS

    string

    TRUE or FALSE

    Versions 4.1.1 and earlier.

    if TRUE print forcing data debugging files

    PRT_SNOW

    string

    TRUE or FALSE

    Versions 4.1.1 and earlier.

    if TRUE print snow debugging files

    PRT_MOIST

    string

    TRUE or FALSE

    Versions 4.1.1 and earlier.

    if TRUE print soil moisture debugging files

    PRT_TEMP

    string

    TRUE or FALSE

    Versions 4.1.1 and earlier.

    if TRUE print soil thermal debugging files

    DEBUG_DIR

    string

    char * pathname

    Versions 4.1.1 and earlier.

    debugging files output directory (default directory is the current directory, '.')


    Example Global Parameter File:

    View the example here.


    VIC Administrator
    Last modified: Thu Feb 16 21:02:03 PDT 2012