VIC Frozen Soils Model File Types

All input files, and variables described below are for the VIC-2L water balance model as modified by Dag Lohman. This version of the VIC model uses snow melt and temperature variables computed off-line, and stored in a separate file

Global Parameters:

Global parameters are read from a single line input file in the format shown below. Values are stored in struct global_param_struct.

Column	Variable Type	Variable Name	Description
1	integer	model_type	Type of VIC model to run
2	float	resolution	Grid resolution
3	integer	startyear	Year to start simulation
4	integer	startmonth	Month to start model
5	integer	startday	Day to start model
6	double	wind_h	Height of wind measurements
7	double	measure_h	Height of measurements

Soil Parameters:

Soil parameters are read from the soil parameter data file using the formats shown below. All values are read into struct soil_con_struct.

Column	Variable Type	Variable Name	Description
1	integer	flag	flag (1=run model)
2	integer	gridcell	grid cell number
3	float	lat	latitude of cell
4	float	lng	longitude of cell
5	double	b_infilt	infiltration parameter
6	double	max_moist_tot	maximum moisture allowed in layer
7	double	Ds	Subsurface flow rate
8	double	Dsmax	Maximum subsurface flow rate
9	double	Ws	Soil moisture content
10	double	c	c
11	double	maxsoilmoist2factor	Maximum soil moisture of layer 2
12	double	expt	expt
13	double	Ksat	Saturated Hydrologic Conductivity
14	double	init_top_moist	Initial moisture for top layer
15	double	init_bottom_moist	Initial moisture for bottom layer
16	float	elevation	Elevation

Vegitation Parameters:

Vegitation parameters are read from an input file in the format shown below. Each grid cell can contain multiple types of vegetation, so each line of the input file contains information about all vegetation types within a grid cell. Data is stored in struct veg_con_struct.

Column	Variable Type	Variable Name	Description
1	integer	vegcel	Grid cell number of current record
2	integer	vegtat_type_num	Number of vegetation types in grid cell
3 …	See Below		Individual vegetation type records

Individual vegetation type records:

Column	Variable Type	Variable Name	Description
1	integer	veg_class	Class number of vegetation
2	double	Cv	Specific heat of vegetation type
3	double	rarc	Architectual Resistance
4	double	rs	Minimum Stomatal Resistance
5	double	root1	Percent of roots in layer 1
6	double	root2	Percent of roots in layer 2
7-18	12 * double	LAI[]	Monthly Leaf Area Index
19	double	rough	roughness of vegetation
20	double	displacement	displacement

Atmospheric Variables:

Atmospheric variables are read from two files, the first contains atmospheric or weather data, the second contains information on the snow pack. Snow pack data is determined outside of the VIC model using SnowTherm. All variables are read in as strings and converted to the types listed below. Atmospheric variables are stored in struct atmos_data_struct.

Variables Read from Atmospheric Data File (n lines in file, 1 per time step):

Column	Variable Type	Variable Name	Description
1	float	melt	Snow melt flux
2	float	prec	Precipitation
3	float	air_temp	Air temperature
4	float	pan_evap	Pan evaporation
5	float	rain_plus_snow	Rain plus Snow input
6			Unused
7	float	rainonly	Amount of rain
8			Unused
9			Unused
10			Unused
11	float	albedo	Surface albedo

Wind is initialized to 8.0.

Variable Read from Snow Data File:

Column	Variable Type	Variable Name	Description
1			Unused
2	double	tmax	Maximum Daily Temperature
3	double	tmin	Minimum Daily Temperature

The following is a summary of the files and subroutines included in Dag Lohman's cleaned version of the VIC Two Layer model.

Model Main Subroutines:

Filename	Subroutine Name	Input Variables	Returned Variables	Description
vic2l.c	main	Parameter, Data and Output File Names	None	This program monitors file I/O and runs model.
cmd_proc.c	cmd_proc	Command Line Arguments	Filename Struct	Extracts filenames and other info from command line arguments.
aurad.c	fltrad	sehortz, swhortz, slat, jday, tranday	Short Wave Raditation	Computes net shortwave radiation using sun-earth geometry, and transmissivity.
	shrad	asp, dslop, slat, sehorz, swhorz, jday, tranday	Short Wave Radiation	Computes net shortwave radiation as above, but including surface characteristics.
rad_and_vpd.c	rad_and_vpd	Atmos Data Struct, Soil Data Struct, Number of Records	Array of DMY Structs	Calculates daily evaporation, and radiation balance.
calc_netshort.c	calc_netshort		Net Short Wave Radiation	Calculates the short wave radiation.
calc_trans.c	calc_trans	Delta T, Elevation	trans	Computes transmissity???
long_shortwave.c	in_shortwave	Latitude, Day, Transmissivity	Incoming Solar Radiation	Computes incoming solar radiation, based on time of year, latitude, and clarity of atmosphere.
	net_out_longwave	Transmissivity, Trans of Clear Air, Air Temp, Vapor	Net Outgoing Longwave Radiation	Computes outgoing longwave radiation.
twolayer_vic_roff.c	twolayer_vic_roff	Soil Data Struct, PPT	Soil Struct	Computes runoff from grid cell.
arno_evap.c	arno_evap	Atmos Data Struct, Soil Data Struct, Global Struct	Soil Struct	Computes evaportation of an area as a percentage based on saturation.
canopy_evap.c	canopy_evap	Atmos Data Struct, Soil Data Struct, Veg Data Struct, Global Struct	Soil Struct, Veg Struct	Computes evaporation from canopy using penman equations.
priestley.c	priestley	Air Temp, Net Radiation	Potential Evaporation	Computes potential evaporation using Priestley-Taylor.
penman.c	penman	Net Radiation, Vapor Pressure Deficit, Aerodynamical Resistance, Minimum Stomatal Resistance, Architectural Resistance
svp.c	svp	Temp	svp
	svp_slope	Temp	svp_slope

Model Input and Output:

Filename	Subroutine Name	Input Variables	Returned Variables	Description
get_global_param.c	get_global_param	Global Parameter File	Global Struct	Reads in global parameters from global input file.
read_soilparam.c	read_soilparam	Soil Parameter File	Soil Struct	Reads soil parameters from soil input file
read_vegparam.c	read_vegparam	Vegitation Parameter File, Grid Cell	Vegitation Struct	Reads vegetation parameters from vegetation input file.
read_atmosdata.c	read_atmosdata	Atmos Data File, Snow Data File	Atmos Data Struct, Number of Records	Reads atmospheric and snow data from input files.
write_vegparam.c	write_vegparam	Vegitation Struct	None	Writes values of vegetation parameters to stdout
write_atmosdata.c	write_atmosdata	Atmos Data Struct, Number of Records	None	Writes atmospheric data values to stdout.
write_data.c	write_data	Array of Out Data, Outfile Struct, Number of Records	None	Writes output for all time steps in simulation.
make_infiles.c	make_infiles	Soil Struct	Input File Pointers, Output File Pointers, Filename Struct	Creates input and output filenames using current grid cell lat and lng.
make_outfiles.c	make_outfiles	Input File Pointer Struct	Output File Pointer Struct	Creates and opens output files.
check_files.c	check_files	Filename Struct	File Pointer Struct	Opens soil, vegetation, and global parameter files.
open_file.c	open_file	Filename, Filetype	File Pointer	Checks and opens File.
close_files.c	close_files	Infile Struct, Outfile Struct	None	Closes all files.

Data Array Controls:

Filename	Subroutine Name	Input Variables	Returned Variables	Description
make_dmy.c	make_dmy	Global Struct	Array of DMY Struct	Creates Day, Month, Year records for each time step.
make_veg_var.c	make_veg_var	Number of Vegitation Types	Array of Vegitation Structs	Creates vegetation records for each vegetation type.
make_soil_var.c	make_soil_var	Number of Vegitation Types	Array of Soil Structs	Creates soil records for each vegetation type.
make_out_data.c	make_out_data	Number of Records	Array of Out Data Structs	Creates out data records for each time step.
put_data.c	put_data	Soil Struct, Vegitation Struct, Vegitation Data Struct	Output Struct	Sums contributions from all vegetation types, and computes final grid values for output.

Initialization Routines:

Filename	Subroutine Name	Input Variables	Returned Variables	Description
initialize_soil.c	initialize_soil	Soil Data Struct, Number of Vegitation Types	Soil Struct	Initializes upper and lower soil layers using initial moisture values.
initialize_veg.c	initialize_veg	Vegitation Data Struct, Global Struct	Vegitation Struct	Initializes vegetation with dew levels half maximum.

All data structures are identified in the header file vic2l_def.h. The following tables detail the structures, and the variables they contain.

struct infiles_struct:

Variable Type	Variable Name	Description
FILE *	soilparam	Soil parameters file.
FILE *	vegparam	Vegitation parameters file.
FILE *	snowout	Snow model output file.
FILE *	snowin	Snow model input file.
FILE *	globalparam	Global parameters file.

struct outfiles_struct:

Variable Type	Variable Name	Description
FILE *	moist1	Moisture content for first layer
FILE *	moist2	Moisture content for second layer
FILE *	evap	Evaporation output file.
FILE *	runoff	Runoff output file.
FILE *	baseflow	Baseflow output file.

struct filenames_struct:

Variable Type	Variable Name	Description
char *	snowout	Filename for snow model output file.
char *	snowin	Filename for snow model input file.
char *	global	Filename for global parameter input file.
char *	soil	Filename for soil input file.
char *	veg	Filename for vegetation input file
char *	result_dir	Pathname for result files.
char *	moist1	Filename for first layer output file
char *	moist2	Filename for second layer output file.
char *	evap	Filename for evaporation output file.
char *	runoff	Filename for runoff output file.
char *	baseflow	Filename for baseflow output file.

struct global_param_struct:

Variable Type	Variable Name	Description
int	model_type	Unused at this time
float	resolution	Grid cell resolution in degrees.
int	startyear	Year of start of simulation
int	startmonth	Month of start of simulation.
int	startday	Day of start of simulation
int	nrecs	Number of records (or time steps) in simulation.
double	wind_h	Height at which wind was measured
double	measure_h	Height of surface measurements

struct soil_con_struct:

Variable Type	Variable Name	Description
int	gridcel	Grid cell number
float	lat	Latitude of current grid cell.
float	lng	Longitude of current grid cell.
double	b_infilt	Infiltration parameter
double	max_moist_tot	Maximum total moisture content.
double	Ds	Subsurface flow rate
double	Dsmax	Maximum subsurface flow rate
double	Ws	Soil moisture content
double	c
double	maxsoilmoist2factor	Maximum soil moisture content of layer 2
double	expt	Exponent
double	Ksat	Saturated hydraulic conductivity
double	init_top_moist	Initial moisture content of top layer
double	init_bottom_moist	Initial moisture content of bottom layer
double	evapfactor	Evaporation factor
float	elevation	Elevation of grid cell
double	max_moist1	Maximum moisture content of layer 1
double	max_moist2	Maximum moisture content of layer 2
double	max_infil	Maximum infiltration rate
double	Wcr1	Critical moisture content of first layer
double	Wcr2	Critical moisture content of second layer
double	Wpwp1
double	Wpwp2
double	rough	Roughness

struct veg_con_struct:

Variable Type	Variable Name	Description
int	vegetat_type_num	Number of vegetation types in grid cell
int	veg_class	Vegitation class number
double	Cv	Specific heat of plant
double	Cv_sum
double	rarc	Architectual roughness
double	rs	Stomatal roughness
double	root1	Percentage of roots in first layer
double	root2	Percentage of roots in second layer
double	LAI[12]	Monthly leaf area index for vegetation type
double	rough	Roughness
double	displacement
double	Wdmax[12]

struct atmos_data_struct:

Variable Type	Variable Name	Description
double	melt	Amount of snow melt in grid cell
double	prec	Amount of precipitation in grid cell
double	air_temp	Current air temperature in grid cell
double	pan_evap	Pan evaporation rate in grid cell
double	rain_plus_snow
double	rainonly
double	wind	Current wind
double	sun_hr	Solar hour, for use in computing incoming solar radiation
double	rad	Current radiation
double	vpd	Vapor pressure deficit
double	pressure	Atmospheric pressure at surface
double	rel_humid	Relative humidity
double	tmin	Minimum daily temperature
double	tmax	Maximum daily temperature
double	priest	Evaporation calculated by preistly method
double	trans	Atmospheric transmissivity
double	shortwave	Incoming shortwave radiation calculated using aurad subroutine (Used for calculation of vpd)
double	shortwave2	Incoming shortwave radiation used for energy balance (more believable than shortwave)
double	longwave	Net longwave radiation
double	net_short	Net shortwave radiation
double	albedo	Surface albedo

struct dmy_struct:

Variable Type	Variable Name	Description
int	day	Day of current time step
int	month	Month of current time step
int	year	Year of current time step
int	day_in_month	Yearly Julian date (1-365/366)

struct soil_var_struct:

Variable Type	Variable Name	Description
double	moist1[2]	Moisture layer 1
double	moist2[2]	Moisture layer 2
double	baseflow	Computed baseflow within grid cell
double	Q12	Infiltration from first to second layer
double	runoff	Calculated runoff from grid cell
double	evap1	Calculated evaporation from first layer
double	evap2	Calculated evaporation from second layer

struct veg_var_struct:

Variable Type	Variable Name	Description
double	canopyevap	Calculated canopy evaporation
double	Wdew[2]	Calculated amount of dew trapped on plants
double	throughfall	Calculated amount of water that falls through vegetation

struct out_data_struct:

Variable Type	Variable Name	Description
double	evap	Final calculated evaporation
double	runoff	Final calculated runoff
double	baseflow	Final calculated baseflow
double	moist1	Final calculated moisture content of first layer
double	moist2	Final calculated moisture content of second layer