View source for Project File:Continuous Simulations � Optional

Continuous simulations require general information about the watershed location, selection of a method to calculate evapo-transpiration (ET), hydrometeorological (HMET) data in one of three available formats, and the appropriate distributed data either from the Mapping Table file or from GRASS ASCII maps.  

==3.8.1 Required Inputs ==

{| class="thin" width=700px
|- 
! Card !! Argument !! Units !! Description
|- 
| <pre>LONG_TERM</pre> || ''none'' || &nbsp; || Specifies continuous simulation.  REQUIRES one of '''ET_CALC_PENMAN''' or '''ET_CALC_DEARDORFF'''.  <br>
REQUIRES one of three HMET formats.   Also REQUIRES '''INF_REDIST''' or '''INF_RICHARDS'''.
|- 
| <pre>LATITUDE  ##.##</pre> || ''real'' || decimal<br>degrees || Latitude of catchment centroid. 
|- 
| <pre>LONGITUDE  ##.##</pre> || ''real'' || decimal<br>degrees || Longitude of catchment centroid.  
|- 
| <pre>GMT  ##.##</pre> || ''real'' || hr || Number of hours difference between the time zone of the catchment and Greenwich Mean Time (e.g. –6 for EDT).  
|- 
| <pre>SOIL_MOIST_DEPTH  ##.##</pre> || ''real'' || m || Depth of the active soil moisture layer from which ET occurs (m). 
|- 
| <pre>EVENT_MIN_Q  ##.##</pre> || ''real'' || m<sup>3</sup>/s || Threshold discharge for continuing runoff events.
|- 
| <pre>ET_CALC_PENMAN</pre> || ''none'' || Calculate evapo-transpiration using the Penman-Monteith (1971) method.
|- 
|}

==3.8.2 Seasonal Canopy Resistance - Optional==

{| class="thin" width=700px
|- 
! Card !! Argument !! Units !! Description
|- 
| <pre>SEASONAL_RS</pre> || ''none'' || Specifies that the values of canopy resistance vary seasonally
|}

==3.8.3 Format of Hydrometeorological (HMET) Data – Required, Select One Format==

{| class="thin" width=700px
|- 
! Card !! Argument !! Description
|- 
| <pre>HMET_SURFAWAYS  "filename.hmt"</pre> || ''file name'' || ASCII file with hourly HMET data formatted in the form of the NOAA/NCDC Surface Airways Data.  Mutually exclusive with '''HMET_SAMSON''' and '''HMET_WES'''; one required for '''LONG_TERM'''.
|- 
| <pre>HMET_SAMSON  "filename.hmt"</pre> || ''file name'' || ASCII file with hourly HMET data formatted as per the NOAA/NCDC SAMSON CD-ROM data set.  Mutually exclusive with '''HMET_WES''' and '''HMET_SURFAWAYS'''; one required for '''LONG_TERM'''.
|- 
| <pre>HMET_WES  "filename.hmt"</pre> || ''file name'' || ASCII file with hourly HMET data written using a simple format discussed in the Continuous Simulation Section of this document.  Mutually exclusive with '''HMET_SURFAWAYS''' and '''HMET_SAMSON'''; one required for '''LONG_TERM'''.
|}


==3.8.4 ET Parameter Assignment – Required, Select Mapping Table or GRASS ASCII maps==

Long-term simulation parameters must be assigned using either the Mapping Table or providing the GRASS ASCII maps as described below.  Albedo, wilting point, transmission coefficient, vegetation height and canopy resistance are also required for '''ET_CALC_PENMAN'''.

{| class="thin" width=700px
|- 
! Card !! Argument !! Description
|- 
| <pre>ALBEDO  "filename.alb"</pre> || ''map name'' || Name of GRASS ASCII map containing short-wave albedo values (0.0 – 1.0).   
|- 
| <pre>WILTING_POINT  "filename.wtp"</pre> || ''map name'' || Name of GRASS ASCII map containing values of the wilting point volumetric water content (0.0 - 1.0).
|- 
| <pre>TCOEFF  "filename.tcf"</pre> || ''map name'' || Name of GRASS ASCII map containing values of the canopy optical transmission coefficient. (0.0 - 1.0). 
|- 
| <pre>VHEIGHT  "filename.vht"</pre> || ''map name'' || Name of GRASS ASCII map containing values of the vegetation height in m.  This value is used in calculating the aerodynamic resistance of the reference crop (m) and used in assigning root depth when using '''INF_RICHARDS'''.
|- 
| <pre>CANOPY  "filename.cpy"</pre> || ''map name'' || Name of GRASS ASCII map containing values of the canopy average stomatal resistance (s/m). 
|}

==3.8.5 Optional Inputs ==

{| class="thin" width=700px
|- 
! Card !! Argument !! Units !! Description
|- 
| <pre>TOP_LAYER_DEPTH ##.##</pre> || ''real'' || m || If using GAR, can specify a top layer that is less than or equal to '''SOIL_MOIST_DEPTH''', default is '''SOIL_MOIST_DEPTH''' (m). 
|-
| <pre>END_TIME [yr mo day hr min]</pre> || ''date and time'' || date and time || Absolute date and time to end the long term simulation.  Takes the form year month day hour min, such as 2002 6 30 24 00. Used for stopping the simulation before the end of data. 
|
|-
| <pre>START_DATE [yr mo day ]</pre> || ''date'' || year month day || Absolute date to start the long term simulation.  Takes the form year month day, such as 2002 6 30. Used for starting the the simulation after the beginning of the hmet data start.  Must be used with START_TIME.  Start time and date must coincide with a date and time in the hmet series that is not within a precipitation event. 
|
|-
| <pre>START_TIME [hr min]</pre> || ''time'' || hour minute || Absolute date and time to end the long term simulation.  Takes the form of hour min, 24 00. Used for starting the the simulation after the beginning of the hmet data start.  Must be used with START_DATE.  Start time and date must coincide with a date and time in the hmet series that is not within a precipitation event. 
|}


==3.8.6 Snow Card Inputs - Optional ==


'''Cards calling which snow melt algorithm to use''' <br>
{| class="thin" width=700px
|- 
! Melt Method !! Card !! Description
|- 
| '''[[Hybrid Energy Balance]]''' || <pre>default (no card required)</pre> || 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]]''' || <pre>NWSRFS_SNOW</pre> || The Temperature Index Method for melting snow is utilized if this card is present in the Project File.
|- 
| '''[[Energy Balance]]''' || <pre>EB_SNOW</pre> || 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''' <br>
{| class="thin" width=700px
|- 
! Card !! Argument !! Units !! Description
|- 
| <pre>NWSRFS_SCF     ##.##</pre> || ''real'' || ''fraction'' || Snow Cover Factor (adjusts for mis-readings in the gage data (see '''[[Continuous:Snowfall_Accumulation_and_Melting]]''').
|- 
| <pre>SNOW_TEMP_BASE ##.##</pre> || ''real'' || &deg;C || Base Temperature ('''MBASE''') at which melt begins in snow.
|- 
| <pre>SNOW_NO_INFILTRATE</pre> || &nbsp; || &nbsp; || This option prevents infiltration in any cell containing snow.
|- 
| <pre>INIT_SWE_DEPTH #.# or File</pre> || 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.
|-
| <pre>SNOW_SWE_FILE  ***.swe</pre> || ''File || m || Outputs time-series snow water equivalent maps (similar to DEP file).
|} <br>

Example file when using '''INIT_SWE_DEPTH'''<br>
[[File:Init_Snow.jpg]]<br>
<br><br>

'''Cards Associated with BOTH [[Hybrid Energy Balance]] and [[Temperature Index]] Methods''' <br>
{| class="thin" width=700px
|- 
! Card !! Argument !! Units !! Description
|- 
| <pre>NWSRFS_FR_USE  ##.##</pre> || ''real'' || ''fraction'' || Specifies the fraction of precipitation in the form of rain when the temperature in the cell drops below '''MBASE'''.
|- 
| <pre>NWSRFS_TIPM       ##.##</pre> || ''real'' || &nbsp; || Snow Cover Thermal Gradient
|- 
| <pre>NWSRFS_NMF        ##.##</pre> || ''real'' || mm/&deg;C/dt || Negative Melt Factor.
|- 
| <pre>NWSRFS_FUA        ##.##</pre> || ''real'' || &nbsp; || Empirical Wind Function Factor.
|- 
| <pre>NWSRFS_PLWHC      ##.##</pre> || ''real'' || % || Percent Liquid Water Holding Capacity.
|- 
| <pre>NWSRFS_ELEV_SNOW  File</pre> || ''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.
|} <br>

Example file when using '''NWSRFS_ELEV_SNOW'''<br>
[[File:Band_NWSRFS.jpg]]<br>
Elevations are in meters, all other values are in their standard formats.
<br><br>

'''Cards Associated with JUST [[Temperature Index]] Method''' <br>
{| class="thin" width=700px
|- 
! Card !! Argument !! Units !! Description
|- 
| <pre>NWSRFS_MF_MAX  ##.##</pre> || ''real'' || mm/&deg;C/dt || Maximum Melt Factor, only works with '''NWSRFS_SNOW'''.
|- 
| <pre>NWSRFS_MF_MIN  ##.##</pre> || ''real'' || mm/&deg;C/dt || Minimum Melt Factor, only works with '''NWSRFS_SNOW'''.
|}

'''Cards Associated with Vertical Melt Water Transport ([[Vertical MWT]])''' <br>
{| class="thin" width=700px
|- 
! Card !! Argument !! Units !! Description
|- 
| <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]]''').
|- 
| <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).
|}

'''Cards Associated with Lateral Melt Water Transport ([[Lateral MWT]])''' <br>
{| class="thin" width=700px
|- 
! Card !! Argument !! Units !! Description
|- 
| <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).
|- 
| <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.
|}

'''Cards Associated with [[Orographic Effects]]''' <br>
{| class="thin" width=700px
|- 
! Card !! Argument !! Units !! Description
|- 
| <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.
|- 
| <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.
|- 
| <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.
|- 
| <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.
|}


==3.8.7 Distributed Hydrometeorology Data - Optional ==
This function allows GSSHA to read in raster-based hydrometeorology data.  The input files must be in the same projection as the GSSHA model and must be larger than the model domain.  Please see [[Distributed HMET Data]] for more details.
{| class="thin" width=700px
|- 
! Card !! Argument !! Units !! Description
|- 
| <pre>HMET_ASCII  ***.txt</pre> || ''File || see [[Distributed HMET Data]] || Inputs hyrometeorology data (temperature, cloud cover, direct radiation, global radiation, pressure, relative humidity, and wind speed) in each cell based on hourly Arc/Info ASCII grid files, giving the model more spatial variability.  The files must have a specific format as described in '''[[Distributed HMET Data]]'''.
|}





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