This file controls how the model functions by defining all global parameters and telling it where to get grid cell parameters and atmospheric forcing data. The order of the parameters in the 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.
The following icons are used to identify changes between version 4.0 and 4.0.5 in the documentation:
The following options define values for various global parameters
Option Name |
Option Type |
Description |
|
integer |
number of moisture layers used by the model |
|
|
TIME_STEP |
integer hours, must divide 24 evenly |
model time step in hours (= 24 for water balance) |
|
RESOLUTION  |
float degrees |
model grid cell resolution |
|
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 |
|
ENDYEAR |
integer year |
year model simulation ends |
|
ENDMONTH |
integer month |
month model simulation ends |
|
ENDDAY |
integer day |
day model simulation ends |
|
NRECS |
integer |
number of time steps over which to run model (not needed if end date is defined). NOTE: The number of records must be defined such that the model completes the last day. |
|
SKIPYEAR |
integer years |
Number of years to skip before starting to write output file. Used to reduce output by not including spin-up years. |
|
STATENAME |
char * file name |
path and file name of the state file to be created on the specified date. The SAVE_STATE pre-processor option must be set to TRUE to use this option. |
|
STATEYEAR |
integer year |
year model simulation state is saved. For versions 4.0.5 and earlier, the SAVE_STATE pre-processor option must be set to TRUE to use this option. |
|
STATEMONTH |
integer month |
month model simulation state is saved. For versions 4.0.5 and earlier, the SAVE_STATE pre-processor option must be set to TRUE to use this option. |
|
STATEDAY |
integer day |
day model simulation state is saved. For versions 4.0.5 and earlier, the SAVE_STATE pre-processor option must be set to TRUE to use this option. |
|
WIND_H |
float meters |
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 meters |
height of humidity measurement |
|
integer |
number of thermal solution nodes in the soil column |
|
|
MAX_SNOW_TEMP |
float C |
maximum temperature at which snow can fall |
|
MIN_RAIN_TEMP |
float C |
minimum temperature at which rain can fall |
The following names control which model options are used in the current model run.
Option Name |
Option Type |
Description |
|
FULL_ENERGY |
TRUE or FALSE |
if TRUE calculate full energy balance |
|
FROZEN_SOIL |
TRUE or FALSE |
if TRUE calculate frozen soils |
|
SNOW_MODEL |
TRUE or FALSE |
if TRUE use internal snow model. The model no longer supports being run with forcings from an external snow model. |
|
TRUE or FALSE |
if TRUE use distributed precipitation |
|
|
CALC_SNOW_FLUX |
TRUE or FALSE |
if TRUE compute thermal flux through snow pack |
|
COMPRESS |
TRUE or FALSE |
if TRUE compress input and output files when done (uses gzip) |
|
CORRPREC |
TRUE or FALSE |
if TRUE correct precipitation for gauge undercatch |
|
GRID_DECIMAL |
integer |
number of decimals to use in gridded file name extensions |
|
integer AND char* |
maximum number of snow elevation bands to use, and the name (with path) of the snow elevation band file. |
|
|
PRT_SNOW_BAND |
TRUE or FALSE |
if TRUE then print snow variables for each snow band in a separate output file (snow_band_*). |
|
ARC_SOIL |
TRUE or FALSE |
if TRUE read soil parameters from ARC/INFO ASCII gridded files |
|
SNOW_STEP |
int |
Time step in hours used to solve the snow model |
|
FORCE_DT |
float[2] |
Time step of the two input files in hours (second file time step must be defined even if it is not used) |
|
int |
Number of defined root zones defined for root distribution. |
|
|
BINARY_OUTPUT |
TRUE or FALSE |
If TRUE write output files in binary (default is ASCII, unless the pre-processor option LDAS_OUTPUT is selected in which case binary is the only option). |
|
BINARY_STATE_FILE |
TRUE or FALSE |
If TRUE writes output state file in binary (default is ASCII, unless the pre-processor option LDAS_OUTPUT is selected in which case binary is the only option). |
|
float |
Minimum observable wind speed. |
|
|
PREC_EXPT |
float |
Exponent used to determine the fraction of a grid cell that receives precipitation (default 0.6). Used only if DIST_PREC option is set to TRUE. |
|
GRND_FLUX |
TRUE or FALSE |
If TRUE model will compute the surface energy balance. The default is TRUE for FULL_ENERGY and FROZEN_SOIL, FALSE for water balance simulations. |
|
QUICK_FLUX |
TRUE or FALSE |
If TRUE model will use the method described by Liang et al. (1999) to compute ground heat flux. If FALSE model will use the method described in Cherkauer and Lettenmaier (1999). TRUE is the default when running FULL_ENERGY, while FALSE is the default when running FROZEN_SOIL. |
|
NOFLUX |
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 FROZEN_SOIL = TRUE). The default is to use a constant temperature bottom boundary. |
|
COMPUTE_TREELINE  |
FALSE or TYPE |
If FALSE the compute treeline feature is disable, else specify default type. |
|
JULY_TAVG_SUPPLIED |
TRUE or FALSE |
If TRUE then VIC will look in the last column of the soil file for the average July temperature. |
This section describes how to define the forcing files needed by the VIC model.
declaringIn release 4.0 there are no longer any pre-defined file types, all forcing files must be defined in the global control file. VIC is able to read forcing data from two files with different time steps, however, it will not disaggregate sub-daily forcing data (e.g. given 3 hour data, VIC will not run at an hourly time step). 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. Note that if you are using two forcing files, 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).
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.
Option Name |
Option Type |
Description |
|
(1*) FORCING1 |
char * 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 |
char * pathname and file prefix, or FALSE |
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) N_TYPES |
int |
Number of columns in the current data file. |
|
(3) FORCE_TYPE  |
char * (parameter type), |
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. |
|
(4) FORCE_FORMAT |
BINARY or ASCII |
Defines the format type for the current forcing file. |
|
(5)FORCE_ENDIAN |
BIG or LITTLE |
Identifies the machine on which the binary forcing files were created as BIG endian (e.g. meter) or LITTLE endian (e.g. ontario). 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. |
|
(6) FORCE_DT |
float |
Time step 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 |
* 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.
This section describes how to define the soil and vegetation parameter files needed to run the VIC model.
Option Name |
Option Type |
Description |
|
SOIL |
char * file name |
either the Soil parameter file or the ARC/INFO Soil Parameter File List name, depending on the setting of ARC_SOIL |
|
SOIL_DIR |
char * directory |
The directory in which to look for all ARC/INFO ASCII gridded parameter files. Used only if ARC_SOIL is TRUE. |
|
VEGPARAM |
char * file name |
|
|
GLOBAL_LAI |
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. |
|
VEGLIB |
char * file name |
|
|
RESULT_DIR |
char * path name |
Model results output directory name |
|
INIT_STATE |
char * full file name |
Tells VIC where to find the optional model state initialization file. |
|
INIT_SOIL |
char * full file name |
Tells VIC where to find the optional soil initialization file. |
|
INIT_SNOW |
char * full file name |
Tells VIC where to find the optional snow initialization file. |
The following options control which debugging output files will be generated, and to which directory they will be written. These routines are designed to aid in debugging modifications to the code, and are not necessarily tested for the current code version. These options will only work if the model code has been compiled with the compiler option LINK_DEBUG set to TRUE.
Option Name |
Option Type |
Description |
|
PRT_FLUX |
TRUE or FALSE |
if TRUE print energy fluxes debugging files |
|
PRT_BALANCE |
TRUE or FALSE |
if TRUE print water balance debugging files |
|
PRT_SOIL |
TRUE or FALSE |
if TRUE print soil parameter debugging files |
|
PRT_VEGE |
TRUE or FALSE |
if TRUE print vegetation parameter debugging files |
|
PRT_GLOBAL |
TRUE or FALSE |
if TRUE print global parameter debugging files |
|
PRT_ATMOS |
TRUE or FALSE |
if TRUE print forcing data debugging files |
|
PRT_SNOW |
TRUE or FALSE |
if TRUE print snow debugging files |
|
PRT_MOIST |
TRUE or FALSE |
if TRUE print soil moisture debugging files |
|
PRT_TEMP |
TRUE or FALSE |
if TRUE print soil thermal debugging files |
|
DEBUG_DIR |
char * pathname |
debugging files output directory (default directory is the current directory, '.') |
Download or view global parameter file for version 4.0.5.
Download or view global file for version 4.0.
Download or view global file for version 4.0.1.
View previous version of this document (for version 4.0.1).
