Snow Card Inputs - Optional

The following tables list all project file cards pertaining to snow accumulation, melt, and melt-water transport.

Cards calling which snow melt algorithm to use

Melt Method	Card	Description
Hybrid Energy Balance	default (no card required)	The Hybrid Energy Balance Method for melting snow is the default, so it is utilized if NWSRFS_SNOW and EB_SNOW are not present in the Project File.
Temperature Index	NWSRFS_SNOW	The Temperature Index Method for melting snow is utilized if this card is present in the Project File.
Energy Balance	EB_SNOW	The Energy Balance Method for melting snow is utilized if this card is present in the Project File.

Cards Associated with All Three Melt Methods

Card	Argument	Units	Description
NWSRFS_SCF ##.##	real	fraction	Snow Cover Factor (adjusts for mis-readings in the gage data (see Continuous:Snowfall_Accumulation_and_Melting).
SNOW_TEMP_BASE ##.##	real	°C	Base Temperature (MBASE) at which melt begins in snow.
SNOW_SWE_FILE ***.swe	File	m	Outputs time-series snow water equivalent maps (similar to DEP file).

Cards Associated with BOTH Hybrid Energy Balance and Temperature Index Methods

Card	Argument	Units	Description
NWSRFS_FR_USE ##.##	real	fraction	Specifies the fraction of precipitation in the form of rain when the temperature in the cell drops below MBASE.
NWSRFS_TIPM ##.##	real		Snow Cover Thermal Gradient
NWSRFS_NMF ##.##	real	mm/°C/dt	Negative Melt Factor.
NWSRFS_FUA ##.##	real		Empirical Wind Function Factor.
NWSRFS_PLWHC ##.##	real	%	Percent Liquid Water Holding Capacity.

Cards Associated with JUST Temperature Index Method

Card	Argument	Units	Description
NWSRFS_MF_MAX ##.##	real	mm/°C/dt	Maximum Melt Factor, only works with NWSRFS_SNOW.
NWSRFS_MF_MIN ##.##	real	mm/°C/dt	Minimum Melt Factor, only works with NWSRFS_SNOW.

Cards Associated with Vertical Melt Water Transport (Vertical MWT)

Card	Argument	Units	Description
SNAP_RETENTION			Uses the SNAP model to simulate the vertical transport of melt-water through the snow pack (Vertical MWT).
VERT_SNOW_RETENTION			Uses the SNAP model to simulate the vertical transport of melt-water through the snow pack (Vertical MWT), but also distributes the melt incrementally over an hour instead of abruptly at every timestep that SNAP is run (which is hourly).

Cards Associated with Lateral Melt Water Transport (Lateral MWT)

Card	Argument	Units	Description
SNOW_DARCY			Simulates the lateral transport of melt-water through the snow pack based on work by Colbeck (1974) (Lateral MWT).
SNOW_REYNOLDS ##.##	real		Reynolds Number at which flow simulation switches from Darcian to regular Overland. Only effects cells covered by snow and only works when SNOW_DARCY card present in Project File.

Cards Associated with Orographic Effects

Card	Argument	Units	Description
OROGVAR_HMET			Adjusts the temperature in each cell based on elevation differences between the cell and the gage site (Orographic Effects).
HMET_ELEV_GAGE ##.##	real	m	Elevation (m) of the gage site where temperature is measured. Only works when OROGVAR_HMET card present in Project File.
HMET_LAPSE_RATE ##.##	real	°C km^-1	Dry adiabatic lapse rate of the area modeled. Only works when OROGVAR_HMET card present in Project File.