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About this component:
*This component was … About this component:</br>*This component was developed as part of the TopoFlow hydrologic model, which was originally written in IDL and had a point-and-click GUI. For more information on TopoFlow, please goto: https://csdms.colorado.edu/wiki/Model:TopoFlow.</br>*When used from within the CSDMS Modeling Tool (CMT), this component has "config" button which launches a graphical user interface (GUI) for changing input parameters. The GUI is a tabbed dialog with a Help button at the bottom that displays HTML help in a browser window.</br>*This component also has a configuration (CFG) file, with a name of the form: <case_prefix>_channels_diff_wave.cfg. This file can be edited with a text editor.</br>*The Numerical Python module (numpy) is used for fast, array-based processing.</br>*This model has an OpenMI-style interface, similar to OpenMI 2.0. Part of this interface is inherited from "CSDMS_base.py".his interface is inherited from "CSDMS_base.py". +
Yes +
No but planned +
Single Processor +
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23:42:43, 17 February 2010 +
Collaborators include: Larry Hinzman (UAF), Bob Bolton, Anna Liljedahl (UAF), Stefan Pohl and others +
This model/component is typically not calibrated to fit data, but is run with a best guess or measured value for each input parameter. +
Available test data sets:
*Treynor watersh … Available test data sets:</br>*Treynor watershed, in the Nishnabotna River basin, Iowa, USA.</br>* (Two large rainfall events.)</br>*Small basin in Kentucky.</br>*Inclined plane for testing.</br>*Arctic watershed data from Larry Hinzman (UAF).</br>*See /data/progs/topoflow/3.0/data on CSDMS cluster./progs/topoflow/3.0/data on CSDMS cluster. +
Several test datasets are stored on the CSDMS cluster at: /data/progs/topoflow/3.0/data. +
The input variables for the Energy Balance … The input variables for the Energy Balance method of estimating runoff due to snowmelt are defined as follows:</br> Q_SW = net shortwave radiation (W / m^2)</br> Q_LW = net longwave radiation (W / m^2)</br> T_air = air temperature (deg C)</br> T_surf = surface (snow) temperature (deg C)</br> RH = relative humidity (none) (in (0,1))</br> p_0 = atmospheric pressure (mbar)</br> u_z = wind velocity at height z (m / s)</br> z = reference height for wind (m)</br> z0_air = surface roughness height (m)</br> h0_snow = initial snow depth (m)</br> h0_swe = initial depth, snow water equivalent (m)</br> ρ_snow = density of the snow (kg / m^3)</br> c_snow = specific heat capacity of snow (J / (kg deg_C))</br> ρ_air = density of the air (kg / m^3)</br> c_air = specific heat capacity of air (J / (kg deg_C))</br> L_f = latent heat of fusion, water (J / kg) (334000)</br> L_v = latent heat of vaporization, water (J / kg) (2500000)</br> e_air = air vapor pressure at height z (mbar)</br> e_surf = vapor pressure at the surface (mbar)</br> g = gravitational constant = 9.81 (m / s^2)</br> κ = von Karman's constant = 0.41 (unitless) </br>The behavior of this component is controlled with a configuration (CFG) file, which may point to other files that contain input data. Here is a sample configuration (CFG) file for this component:</br> Method code: 2</br> Method name: Energy_Balance</br> Time step: Scalar 3600.00000000 (sec)</br> Cp_snow: Scalar 2090.00000000 (J/kg/K)</br> rho_snow: Scalar 300.00000000 (kg/m^3)</br> c0: Scalar 2.70000005 (mm/day/deg C)</br> T0: Scalar -0.20000000 (deg C)</br> h0_snow: Scalar 0.50000000 (m)</br> h0_swe: Scalar 0.15000000 (m)</br> Save grid timestep: Scalar 60.00000000 (sec)</br> Save mr grids: 0 Case5_2D-SMrate.rts (m/s)</br> Save hs grids: 0 Case5_2D-hsnow.rts (m)</br> Save sw grids: 0 Case5_2D-hswe.rts (m)</br> Save cc grids: 0 Case5_2D-Ecc.rts (J/m^2)</br> Save pixels timestep: Scalar 60.00000000 (sec)</br> Save mr pixels: 0 Case5_0D-SMrate.txt (m/s)</br> Save hs pixels: 0 Case5_0D-hsnow.txt (m)</br> Save sw pixels: 0 Case5_0D-hswe.txt (m)</br> Save cc pixels: 0 Case5_0D-Ecc.txt (J/m^2) Case5_0D-Ecc.txt (J/m^2)
Equations Used by the Energy-Balance Metho … Equations Used by the Energy-Balance Method</br></br> M = (1000 * Q_m) / (ρ_water * L_f) = meltrate (mm / sec)</br> M_max = (1000 * h_snow / dt) * (ρ_water / ρ_snow) = max possible meltrate (mm / sec)</br> dh_snow = M * (ρ_water / ρ_snow) * dt = change in snow depth (m)</br> Q_m = Q_SW + Q_LW + Q_h + Q_e - Q_cc = energy flux used to melt snow (W / m^2)</br> Q_h = ρ_air * c_air * D_h * (T_air - T_surf) = sensible heat flux (W / m^2)</br> Q_e = ρ_air * L_v * D_e * (0.662 / p_0) * (e_air - e_surf) = latent heat flux (W / m^2)</br> D_n = κ^2 * u_z / LN((z - h_snow) / z0_air)^2 = bulk exchange coefficient (neutrally stable conditions) (m / s)</br> D_h = D_n / (1 + (10 * Ri)), (T_air > T_surf) = bulk exchange coefficient for heat (m / s) (stable)</br> = D_n * (1 - (10 * Ri)), (Tair < Tsurf) = bulk exchange coefficient for heat (m / s) (unstable)</br> D_e = D_h = bulk exchange coefficient for vapor (m / s)</br> Ri = g * z * (T_air - T_surf) / (u_z^2 (T_air + 273.15)) = Richardson's number (unitless)</br> Q_cc = (see note below) = cold content flux (W / m^2)</br> E_cc(0) = h0_snow * ρ_snow * c_snow * (T_0 - T_snow) = initial cold content (J / m^2) (T0 = 0 now)</br> e_air = e_sat(T_air) * RH = vapor pressure of air (mbar)</br> e_surf = e_sat(T_surf) = vapor pressure at surface (mbar)</br> e_sat = 6.11 * exp((17.3 * T) / (T + 237.3)) = saturation vapor pressure (mbar, not KPa), Brutsaert (1975)vapor pressure (mbar, not KPa), Brutsaert (1975) +
Recommended grid cell size is around 100 meters, but can be parameterized to run with a wide range of grid cell sizes. DEM grid dimensions are typically less than 1000 columns by 1000 rows. +
This model/component needs more rigorous testing. +
None, except visualization software. Grid sequences saved in netCDF files can be viewed as animations and saved as movies using VisIt. +
Another program must be used to create the input grids. This includes a D8 flow grid derived from a DEM for the region to be modeled. The earlier, IDL version of TopoFlow can be used to create some of these. +
The Energy Balance method for modeling snowmelt. +
The basic stability condition is: dt < … The basic stability condition is: dt < (dx / u_min), where dt is the timestep, dx is the grid cell size and u_min is the smallest velocity in the grid. This ensures that flow cannot cross a grid cell in less than one time step. Typical timesteps are on the order of seconds to minutes. Model can be run for a full year or longer, if necessary. run for a full year or longer, if necessary. +
Active +
This process component is part of a spatially-distributed hydrologic model called TopoFlow, but it can now be used as a stand-alone model. +
Scott +
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0.06 +
Standard +
Hydrology +
energy +, balance +, snowmelt +, component +, model called topoflow +, spatially-distributed hydrologic model +, hydrologic model called +, called topoflow +, process component +, component is part +, spatially-distributed hydrologic +, hydrologic model +, model called +, stand-alone model +, topoflow +, model +, process +, part +, basins + and topoflow-snowmelt-energy balance +
basins +
Single +
This site. +
Modification date"Modification date" is a predefined property that corresponds to the date of the last modification of a subject and is provided by <a target="_blank" rel="nofollow noreferrer noopener" class="external text" href="https://www.semantic-mediawiki.org/wiki/Help:Special_properties">Semantic MediaWiki</a>.
16:36:02, 6 June 2025 +
1 +
Snowmelt process component (Energy Balance method) for a D8-based, spatial hydrologic model +
1560 30th street +
80305 +
true +
None (but uses NumPy package) +
Apache public license +
Python +
Minutes to hours +
Through web repository +
https://github.com/peckhams/topoflow +
2001 +
Model developer +
