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scikits.hydroclimpy.lib.evaporation.PotentialEvapoTranspiration.Hargreaves

PotentialEvapoTranspiration.Hargreaves(Kt=None)

Computes the PET [mm.d-1] with the method of Hargreaves and Samani [Hargreaves_Samani_1985].

PET = 0.0135 * (R_s/\lambda) * (T_{avg} + 17.8)

where the solar radiations R_s are estimated from the extraterrestrial solar radiations as R_s = K_t \sqrt{(T_{max}-T_{min})} R_a.

Parameters:

Kt : {None, float}, optional

Regression constant used to approximate solar radiations from temperatures. The default (K_t=0.171 corresponds to the standard value suggested by Hargreaves and Samani [Hargreaves_Samani_1985]. If None, K_t is evaluated from the temperatures range \Delta T as K_t = 0.00185 {\Delta T}^2 - 0.0433 {\Delta T} + 0.4023. [REF_TO_FIND_19xx]

Returns:

PET : TimeSeries

Potential Evapo-Transpiration [mm.d-1].