Meteorological forcing variables
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The meteorological forcing input data are on a daily time step: Daily Minimum and Maximum Air Temperature (Tmin and Tmax respectively; °C), Soil Temperature (Tsoil; °C), Precipitation (mm), Solar Radiation (MJ m-2 day-1), Vapor Pressure Deficit (hPa) (or Relative Humidity; %). The day-time and night-time values of air temperature are computed as follow (Running and Coughlan, 1988):
where Tavg is the Daily Average Air Temperature (°C).
When soil temperature is missing as input data, the model computes values for the upper 10 cm of the soil by an 11-day running weighted average of Tavg and further corrected by the presence of a snowpack.
If snow occurs and Tavg is higher than 0°C, the rate of daily snow melt is estimated by:
where Radsoil is the incident global radiation at the soil surface (kJ m-2 day-1), tcoeff is the snowmelt coeffcient (0.65 Kg m-2 °C-1 day-1), epssnow is the absorptivity of snow (0.6) and Hfus is the latent heat of fusion (335 kJ Kg-1). Otherwise if Tavg is lower than 0°C, snow sublimation is calculated as:
where Hsub is the latent heat of sublimation (2845 kJ Kg-1).