VIC Compile-Time Options - user_def.h File

Name

Type

Description

VERBOSE

TRUE or FALSE

Option for controlling messages sent to the screen:

• FALSE = Only print minimum information: errors, etc.
• TRUE = Print much more information: file opening/closing, warnings, etc.

CLOSE_ENERGY

TRUE or FALSE

Option for handling energy fluxes between components of the land surface (canopy, snow pack, ground):

• FALSE = Estimate energy balance of each component individually, using incoming fluxes from the other components from the previous time step.
• TRUE = Take interactions among the components by iterating: solve each component separately and update the outgoing fluxes from each component, then solve each component again using the updated incoming fluxes from the other components, and repeat until desired exit condition reached.

Note: both methods generally give similar results, but while setting CLOSE_ENERGY to FALSE improves speed, it results in energy balance errors.

LINK_DEBUG

TRUE or FALSE

Option for printing debugging messages (values of components of water or energy balance, or other internal variables):

• FALSE = do not print debugging messages.
• TRUE = print debugging messages.

QUICK_FS

TRUE or FALSE

Option for speeding up frozen soil calculations:

• FALSE = use full equations for estimating maximum unfrozen water content.
• TRUE = use linearized version of maximum unfrozen water content equations, defined in global.h. These equations significantly improve speed when simulating frozen soil.

Note: this method is not fully tested.

QUICK_FS_TEMPS

integer

Number of terms to use in linearized maximum unfrozen water calcuation. This is only used if QUICK_FS is TRUE; otherwise it is ignored.

LOW_RES_MOIST

TRUE or FALSE

Option for improving accuracy of soil moisture drainage calculations:

• FALSE = assume uniform matric potential within each soil layer.
• TRUE = use linear interpolation of logarithm of the matric potential from the two adjacent layers to estimate drainage across the layer boundary (Boone and Wetzel, 1996).

Note: this method is not fully tested.

NO_REWIND

TRUE or FALSE

Option for controlling reading of parameter files:

• FALSE = Rewinds (goes back to the beginning of) parameter files before reading the data for each cell.
• TRUE = Does not rewind parameter files before reading the data for each cell. This saves time but requires that the order of grid cells in all files is the same.

OUTPUT_FORCE

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.

OUTPUT_FORCE_STATS

TRUE or FALSE

Option to compute the statistics of the forcings:

• FALSE = Run a simulation (including disaggregating the forcings).
• TRUE = Do not run a simulation; simply compute the mean, standard deviation, and min and max values of the forcing variables and write them to stdout.

SPATIAL_FROST

TRUE or FALSE

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 is 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.

FROST_SUBAREAS

integer

Number of discrete values in the soil temperature distribution. This is only used if SPATIAL_FROST is TRUE; otherwise it is ignored.

SPATIAL_SNOW

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 a snow slope value as an extra field in the soil parameter file, so that the minimum/maximum snow water equivalents can be computed from the mean value.

EXCESS_ICE

TRUE or FALSE

Optional permafrost behavior:

• FALSE = No excess ice in the soil; porosities, densities, etc are exactly as described in the soil parameter file.
• TRUE = Excess ground ice in the soil. This requires user to specify the initial volumetric ice content of the soil as an additional parameter in the soil parameter file. VIC computes effective porosities, densities, etc. based on presence of excess ground ice. As the excess ice melts, these effective porosities and densities approach their ice-free values. Excess soil moisture resulting from the melt is expelled as runoff or baseflow.

MAXIT_FE

integer

Maximum number of iterations to use in solving the surface energy balance

LAI_WATER_FACTOR

float

Coefficient multiplied by the LAI to determine the amount of water that can be stored in the canopy.

LWAVE_COR

float

Longwave correction factor, used to correct estimated incoming longwave radiation (use 1, unless measured longwave available for calibration)

Name

Type

Description

MAX_VEG

int

Maximum number of vegetation tiles that can be defined within a grid cell (a good rule of thumb is to set this to the number of vegetation classes in your vegetation library file).

MAX_LAYERS

int

Maximum number of soil layers that can be defined within a grid cell.

MAX_NODES

int

Maximum number of soil thermal nodes that can be defined within a grid cell.

MAX_BANDS

int

Maximum number of snow elevation bands that can be defined within a grid cell.

MAX_FRONTS

int

Maximum number of soil freeze/thaw fronts that can be defined within a grid cell.

MAX_LAKE_NODES

int

Maximum number of lake solution nodes that can be defined within a grid cell.