Individual ET methods can be called by substituting the 'methodname' by the function name (e.g. ET.Penman
to call the Penman model).
When the ET model selection is not specified by users, this function determines the default model to use based on the availability of climate data presented. Wherever data are available, the more comprehensive, physically-based models are always preferred over the empirical models, in the following hierarchy:
- If all variables of Tmax/Tmin and RHmax/RHmin and either uz or u2, and either Rs of n or Cd are available, and short crop surface is specified in argument:
Penman-Monteith FAO56 (ET.PenmanMonteith
with crop = "short");
- If all variables of Tmax/Tmin and RHmax/RHmin and either uz or u2, and either Rs of n or Cd are available, and long crop surface is specified in argument:
Penman-Monteith ASCE-EWRI (ET.PenmanMonteith
with crop = "long");
- If all variables of Tmax/Tmin and RHmax/RHmin and either uz or u2, and either Rs of n or Cd are available, and no surface is specified:
Penman (ET.Penman
);
- If all variables of Tmax/Tmin and RHmax/RHmin, and either Rs of n or Cd are available:
Priestley-Taylor (ET.PriestleyTaylor
);
- If all variables of Tmax/Tmin and either Rs of n or Cd are available:
Makkink (ET.Makkink
);
- If all variables of Tmax/Tmin are available:
Hargreaves-Samani (ET.HargreavesSamani
).