Difference between revisions of "Snow Card Inputs - Optional"

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! Card !! Argument !! Units !! Description
 
! Card !! Argument !! Units !! Description
 
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| <pre>SNAP_RETENTION</pre> || &nbsp; || &nbsp; || Uses the SNAP model (Albert & Krajeski, 1998) to simulate the vertical transport of melt-water through the snow pack ('''[[Vertical MWT]]''').
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| <pre>SNAP_RETENTION</pre> || &nbsp; || &nbsp; || NOT RECOMMENDED AT THIS TIME.  Uses the SNAP model (Albert & Krajeski, 1998) to simulate the vertical transport of melt-water through the snow pack ('''[[Vertical MWT]]''').  Use of SNAP is not currently recommended.
 
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| <pre>VERT_SNOW_RETENTION</pre> || &nbsp; || &nbsp; || Uses the SNAP model (Albert & Krajeski, 1998) 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).
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| <pre>''Default''</pre> || &nbsp; || &nbsp; || Uses the SNAP model (Albert & Krajeski, 1998) to simulate the depth and porosity of the snowpack. Vertical transport of melt-water through the snow pack ('''[[Vertical MWT]]''') is simulated using methods by Bengtsson (1982).  Melt waves are created that distributes the melt incrementally over an hour instead of abruptly at every timestep.
 
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! Card !! Argument !! Units !! Description
 
! Card !! Argument !! Units !! Description
 
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| <pre>SNOW_DARCY    ##.##</pre> || ''real'' || m s<sup>-1</sup> || Simulates the lateral transport of melt-water through the snow pack based on work by Colbeck (1974) ('''[[Lateral MWT]]''').  The user specifies the initial hydraulic conductivity of the snow pack (m s<sup>-1</sup>), but the hydraulic conductivity changes with time according to the SNAP model (Albert & Krajeski, 1998).
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|<pre>ROUTE_LAT_SNOW </pre> || ''none'' ||  || Simulates the lateral transport of melt-water through the snow pack based on work by Colbeck (1974) ('''[[Lateral MWT]]''').  The hydraulic conductivity changes with time according to the SNAP model (Albert & Krajeski, 1998) unless a user specified value is entered with the card SNOW_DARCY.
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| <pre>SNOW_DARCY    ##.##</pre> || ''real'' || m s<sup>-1</sup> || Simulates the lateral transport of melt-water through the snow pack based on work by Colbeck (1974) ('''[[Lateral MWT]]''').  The user specifies the hydraulic conductivity of the snow pack used during the duration of the simulation (m s<sup>-1</sup>). Default is to calculate the hydraulic conductivity with SNAP.  Use of SNAP is not currently recommended.
 
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| <pre>SNOW_REYNOLDS  ##.##</pre> || ''real'' || &nbsp; || 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.
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| <pre>SNOW_REYNOLDS  ##.##</pre> || ''real'' || &nbsp; || 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.  CURRENTLY NOT USED.
 
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! Card !! Argument !! Units !! Description
 
! Card !! Argument !! Units !! Description
 
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| <pre>HMET_OROG_GAGES  ***.txt</pre> || ''File || see [[Orographic Effects]] || Adjusts the temperature in each cell based on elevation differences between the cell and multiple gage sites.  The file must have a specific format as shown in '''[[Orographic Effects]]'''.  Model elevation (*.ele file) must be in meters.
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| <pre>HMET_ELEV_GAGE  ##.##</pre> || ''real'' || m || Elevation (m) of the gage site where temperature is measured.  Default value is the lowest elevation cell in your domain.
 
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| <pre>OROGVAR_HMET</pre> || &nbsp; || &nbsp; || Adjusts the temperature in each cell based on elevation differences between the cell and the gage site ('''[[Orographic Effects]]''').  Only works when '''HMET_ELEV_GAGE''' and '''HMET_LAPSE_RATE''' cards present in Project File.  This is an additional option if you do not want to use '''HMET_OROG_GAGES'''.  Only one temperature gage used for this option.  Model elevation (*.ele file) must be in meters.
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| <pre>YES_DALR_FLAG    #.#####</pre> || ''real'' || &deg;C m<sup>-1</sup> || Dry adiabatic lapse rate of the area modeled.  Best when '''HMET_ELEV_GAGE''' card is present in Project File.  Value should be positive and between 0.0045 and 0.00981 &deg;C m<sup>-1</sup>.  Please see '''[[Orographic Effects]]''' for more information.
 
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| <pre>HMET_ELEV_GAGE  ##.##</pre> || ''real'' || m || Elevation (m) of the gage site where temperature is measured.  Only works when '''OROGVAR_HMET''' and '''HMET_LAPSE_RATE''' cards present in Project File.
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| <pre>''DEFAULT''</pre> || ''none'' || &deg;C m<sup>-1</sup> || Lapse rate is calculated within GSSHA using HMET data and the elevation of the gage site.  Lapse rate is then applied to adjust the temperature, pressure, and relative humidity of each cell within the basin.  Best when '''HMET_ELEV_GAGE''' card is present in Project File.  Please see '''[[Orographic Effects]]''' for more information.
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| <pre>HMET_LAPSE_RATE  ##.##</pre> || ''real'' || &deg;C km<sup>-1</sup> || Dry adiabatic lapse rate of the area modeled.  Only works when '''OROGVAR_HMET''' and '''HMET_ELEV_GAGE''' cards present in Project File.
 
 
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Latest revision as of 23:52, 28 December 2013

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_NO_INFILTRATE
     This option prevents infiltration in any cell containing snow. 
INIT_SWE_DEPTH #.# or File
 real or File m Initializes the snow water equivalent (SWE) for the entire model. If a value is specified the entire model initializes with that value of SWE. A map file may also be specified. The projection and spatial coordinates must be the same as the model. An example input file is shown below. 
SNOW_SWE_FILE  ***.swe
 File m Outputs time-series snow water equivalent maps (similar to DEP file).

Example file when using INIT_SWE_DEPTH
Init Snow.jpg



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. 
NWSRFS_ELEV_SNOW  File
 File depends on parameter This card allows some of the parameters related to snow to be varied depending on elevation using elevation bands. Model elevation (*.ele file) must be in meters. The format of the input file is shown below.

Example file when using NWSRFS_ELEV_SNOW
Band NWSRFS.jpg
Elevations are in meters, all other values are in their standard formats.


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)
The implementation of SNAP for transport through the snow is considered experimental, and is not reccomended at this time.

Card Argument Units Description 
SNAP_RETENTION
     NOT RECOMMENDED AT THIS TIME. Uses the SNAP model (Albert & Krajeski, 1998) to simulate the vertical transport of melt-water through the snow pack (Vertical MWT). Use of SNAP is not currently recommended. 
''Default''
     Uses the SNAP model (Albert & Krajeski, 1998) to simulate the depth and porosity of the snowpack. Vertical transport of melt-water through the snow pack (Vertical MWT) is simulated using methods by Bengtsson (1982). Melt waves are created that distributes the melt incrementally over an hour instead of abruptly at every timestep.



Cards Associated with Lateral Melt Water Transport (Lateral MWT)

Card Argument Units Description 
ROUTE_LAT_SNOW
none Simulates the lateral transport of melt-water through the snow pack based on work by Colbeck (1974) (Lateral MWT). The hydraulic conductivity changes with time according to the SNAP model (Albert & Krajeski, 1998) unless a user specified value is entered with the card SNOW_DARCY. 
SNOW_DARCY     ##.##
 real m s-1 Simulates the lateral transport of melt-water through the snow pack based on work by Colbeck (1974) (Lateral MWT). The user specifies the hydraulic conductivity of the snow pack used during the duration of the simulation (m s-1). Default is to calculate the hydraulic conductivity with SNAP. Use of SNAP is not currently recommended. 
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. CURRENTLY NOT USED.



Cards Associated with Orographic Effects

Card Argument Units Description 
HMET_ELEV_GAGE   ##.##
 real m Elevation (m) of the gage site where temperature is measured. Default value is the lowest elevation cell in your domain. 
YES_DALR_FLAG    #.#####
 real °C m-1 Dry adiabatic lapse rate of the area modeled. Best when HMET_ELEV_GAGE card is present in Project File. Value should be positive and between 0.0045 and 0.00981 °C m-1. Please see Orographic Effects for more information. 
''DEFAULT''
 none °C m-1 Lapse rate is calculated within GSSHA using HMET data and the elevation of the gage site. Lapse rate is then applied to adjust the temperature, pressure, and relative humidity of each cell within the basin. Best when HMET_ELEV_GAGE card is present in Project File. Please see Orographic Effects for more information.


GSSHA User's Manual

3 Project File
3.1     Required Inputs
3.2     Mapping Table – Optional
3.3     Overland Flow – Required
3.4     Interception – Optional
3.5     Rainfall Input and Options – Required
3.6     Infiltration – Optional
3.7     Channel Routing – Optional
3.8     Continuous Simulations – Optional
3.9     Saturated Groundwater Flow – Optional
3.10     Soil Erosion – Optional
3.11     Constituent Transport – Optional
3.12     Subsurface Drainage Network – Optional
3.13     Output Files – Required


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