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ENRGY

Physical-based distributed glacier melt model.

Computes ice and snow ablation based on heat amount available for melt.

Heat balance equation

Heat available for melt is calculated from glacier surface heat budget equation, which incorporates:

• shortwave radiation flux;
• longwave radiation flux;
• turbulent heat fluxes (assuming stable atmospheric conditions).

Input data

Meteorological observations from AWS at the glacier surface, DEM and albedo map.

Assumptions

• temperature of melting surface is assumed to be constant and equaling 0°C.
  Hence, the water vapour partial pressure at the surface always equals 611 Pa;
• atmospheric conditions are always stable - true for ablation season;
• meltwater is removed instantaneously - neither percolation nor refreezing is simulated.

Model constraints

• glacier surface is presented by bare ice only - snow cover is not simulated;
• ground (in-glacier) heat flux is not modelled;
• penetration of shorwave radiation below surface is not modelled
  => all the flux is consumed by the surface itself;
• direct-to-diffuse ratio of solar radiation does not change according to cloudiness and is assumed constant
  => may overestimate topographic shading under cloudy conditions.
• sensible heat flux of rain is not modelled;
• NOTE: bulk aerodynamic technique, used for turbulent heat fluxes, is not the most precise one.