Model help:TopoFlow-Snowmelt-Degree-Day

TopoFlow-Snowmelt-Degree-Day

This module is the snowmelt process component (Degree-Day method) for a D8-based, spatial hydrologic model

Model introduction

This process component is part of a spatially-distributed hydrologic model called TopoFlow, but it can now be used as a stand-alone model.

Model parameters

Parameter	Description	Unit
Component status		Enabled/Disabled
Input directory
Output directory
Site prefix	file prefix for the study site
Case prefix	file prefix for the model scenario
Number of steps	Number of time steps
Time step	timestep for snow melt process	sec
Cp_snow type	allowed input types (Scale/Grid/Time_series/Grid_sequences)
Cp_snow	heat capacity of snow	J/kg/K
ρ_snow type	allowed input types (Scale/Grid/Time_series/Grid_sequences)
ρ_snow	density of snow	kg / m³
c0 type	allowed input types (Scale/Grid/Time_series/Grid_sequences)
c0	degree-day coefficient	mm/day/degree C
T0 type	allowed input types (Scale/Grid/Time_series/Grid_sequences)
T0	reference temperature	deg C
h0_snow type	allowed input types (Scale/Grid/Time_series/Grid_sequences)
h0_snow	depth of snow	m
h0_swe type	allowed input types (Scale/Grid/Time_series/Grid_sequences)
h0_swe	depth of snow water equivalent (SWE)	m

Parameter	Description	Unit
Save grid timestep	time interval between saved grid	sec
Save mr grids toggle	option to save grids of snow meltrate
Save mr grids file	filename for grid stack of snow meltrate	m / s
Save hs grids toggle	option to save grids of snow depth
Save hs grids file	filename for grid stack of snow depth	m
Save sw grids toggle	option to save grids of snow water equivalent
Save sw grids file	filename for grid stack of snow water equivalent	m
Save cc grids toggle	option to save grids of cold content
Save cc grids file	filename for grid stack of cold content	J / m²

Parameter	Description	Unit
Save pixels timestep	time interval between time series value	sec
Save mr pixels toggle	option to save time series of snow meltrate
Save mr pixels file	filename for time series of snow meltrate	m / s
Save hs pixels toggle	option to save time series of snow depth
Save hs pixels file	filename for time series of snow depth	m
Save sw pixels toggle	option to save time series of snow water equivalent
Save sw pixels file	filename for time series of snow water equivalent	m
Save cc pixels toggle	option to save time series of cold content
Save cc pixels file	filename for time series of cold content	J / m²

Uses ports

• Meteorology (for air temperature, T_air, etc.)

Provides ports

• Snow (snowmelt)
• Configure (tabbed dialog GUI to change settings)
• Run (only if used as the Driver)

Main equations

Meltrate, mm/sec

[math]\displaystyle{ M= \left ( c_{0} / 86400 \right) \ast \left ( T_{air} - T_{0} \right) }[/math]

(1)

Max possible meltrate, mm/sec

[math]\displaystyle{ M_{max}= \left ( 1000 \ast h_{snow} / dt \right) \ast \left ( \rho_{water} / \rho_{snow} \right) }[/math]

(2)

Change in snow depth, meters

[math]\displaystyle{ dh_{snow}= M \ast \left (\rho_{water} / \rho_{snow}\right) dt }[/math]

(3)

Nomenclature

Symbol	Description	Unit
c₀	coefficient	-
T₀	threshold temperature	deg C
T_air	air temperature	deg C
ρ_snow	density of the snow	kg / m^3
ρ_water	density of liquid water, 1000	kg / m^3
h0_snow	initial snow depth	m
h_snow	snow depth	m
h0_swe	initial depth, snow water equivalent	m
h_swe	depth, snow water equivalent	m
M	meltrate	mm / sec
M_max	max possible meltrate	mm / sec
d_h	change in snow depth	m

Notes

For each variable, you may choose from the droplist of data types. For the "Scalar" data type, enter a numeric value with the units indicated in the dialog. For the other data types, enter a filename. Values in files must also have the indicated units.

Single grids and grid sequences are assumed to be stored as RTG and RTS files, respectively. Time series are assumed to be stored as text files, with one value per line. For a time series or grid sequence, the time between values must coincide with the timestep provided.

All variables and their units can be seen by expanding the Nomenclature section above.

Examples

An example run with input parameters, BLD files, as well as a figure / movie of the output

Follow the next steps to include images / movies of simulations:

Upload file: https://csdms.colorado.edu/wiki/Special:Upload
Create link to the file on your page: [[Image:<file name>]].

Developer(s)

Scott Peckham

References

Zhang, Z., D.L. Kane and L.D. Hinzman (2000) Development and application of a spatially-distributed Arctic hydrological and thermal process model (ARHYTHM), Hydrological Processes, 14, 1017-1044.

Links

Related Help Pages

Model Metadata