ebsm (Gray and Landine, 1987)
This module is defined in Classebsm and is an energy-budget snowmelt model applicable to the Canadian Prairies.
Observations
- QnD (W/m^2 day) - net radiation. Optional.
Variables
- snowmeltD (mm/d) - snowmelt.
- cumsnowmelt (mm) - cummulative snowmelt.
- LW_ebsm (mm/d) - liquid water in snowpack. State variable.
- u_ebsm (MJ/m^2*d) - snowpack energy deficit. State variable.
- Qmelt (MJ/m^2*d) - Qmelt = Qn+Qh+Qe+Qp.
- Qn_ebsm (MJ/m^2*d) - net radiation.
- Qh_ebsm (MJ/m^2*d) - sensible heat.
- Qe_ebsm (MJ/m^2*d) - latent heat.
- Qp_ebsm (MJ/m^2*d) - input from rainfall.
- Qe_Subl (mm/day) - latent heat sublimation.
- cumQe_subl(mm) - cummulative latent heat sublimation.
Parameters
- tfactor (mm/d*/ºC) - degree day melt factor.
- nfactor (mm*m^2/MJ*d) - net radiation factor.
- delay_melt () - inhibits any melt before this date. Only used when tfactor and nfactor are both zero. Default value not suitable for Southern Hemisphere
- basin_area (km^2) - basin area.
- hru area (km^2) - HRU area.
- Albedo () - areal albedo.
- Qe_subl_SWE () - 0 - add to 'Qmelt' (original version), 1 - take Qe_subl from SWE .
Variable Inputs
- hru_tmean (obs) (ºC)
- hru_tmax (obs) (ºC)
- hru_tmin (obs) (ºC)
- hru_umean (obs) (m/s)
- hru_rhmean (obs) (%)
- hru_Sun_Act (obs) (hr)
- net_rain (*) (mm Dt)
- QdroD (global) (MJ/m^2)
- QdfoD (global) (MJ/m^2)
- SunMax (global) (h)
- SWE (*) (mm)
- albedo (albedo) ()
- meltflag (albedo) ()
Useage.
tfactor and nfactor NOT equal to zero
For comparison there is an option to use the simplified energy budget method proposed by Kustas et al.(1994). In this degree-day algorithm the increased melting later in the season is simulated using a net radiation term.
Melt = tfactor*tmax + nfactor*QnD, where the observation QnD is the net all-wave radiation calculated from a module.
tfactor and nfactor equal to zero
If both parameters tfactor and nfactor are set equal to zero for an HRU, the module uses the original ebsm.f algorithm otherwise the simplified degree-day algorithm is used using the values set in tfactor and nfactor.
Observation QnD is used if available, otherwise Qn is calculated as in the original algorithm.
Over snow during melt;
Qn = -0.53+0.47*(QdroD+QdfoD)*(0.52+0.52*sunact/sunmax)*(1.0-Albedo)
An external observation QnD may be generated using modules long, NeedleLeaf and macro modules Slope_Qsi.mcr and Convert_Qsn_QnD.mcr.