pyet.combination.priestley_taylor#
- pyet.combination.priestley_taylor(tmean, rs=None, rn=None, g=0, tmax=None, tmin=None, rhmax=None, rhmin=None, rh=None, pressure=None, elevation=None, lat=None, n=None, nn=None, rso=None, a=1.35, b=-0.35, alpha=1.26, albedo=0.23, kab=None, as1=0.25, bs1=0.5, clip_zero=True)[source]#
Potential evapotranspiration calculated according to Priestley and Taylor (1972).
- Parameters:
tmean (pandas.Series or xarray.DataArray) – average day temperature [°C].
rs (float or pandas.Series or xarray.DataArray, optional) – incoming solar radiation [MJ m-2 d-1].
rn (float or pandas.Series or xarray.DataArray, optional) – net radiation [MJ m-2 d-1].
g (float or pandas.Series or xarray.DataArray, optional) – soil heat flux [MJ m-2 d-1].
tmax (float or pandas.Series or xarray.DataArray, optional) – maximum day temperature [°C].
tmin (float or pandas.Series or xarray.DataArray, optional) – minimum day temperature [°C].
rhmax (float or pandas.Series or xarray.DataArray, optional) – maximum daily relative humidity [%].
rhmin (float or pandas.Series or xarray.DataArray, optional) – mainimum daily relative humidity [%].
rh (float or pandas.Series or xarray.DataArray, optional) – mean daily relative humidity [%].
pressure (float or pandas.Series or xarray.DataArray, optional) – atmospheric pressure [kPa].
elevation (float or xarray.DataArray, optional) – the site elevation [m].
lat (float or xarray.DataArray, optional) – the site latitude [rad].
n (float or pandas.Series or xarray.DataArray, optional) – actual duration of sunshine [hour].
nn (float or pandas.Series or xarray.DataArray, optional) – maximum possible duration of sunshine or daylight hours [hour].
rso (float or pandas.Series or xarray.DataArray, optional) – clear-sky solar radiation [MJ m-2 day-1].
a (float, optional) – empirical coefficient for Net Long-Wave radiation [-].
b (float, optional) – empirical coefficient for Net Long-Wave radiation [-].
alpha (float, optional) – calibration coefficient [-].
albedo (float, optional) – surface albedo [-].
kab (float, optional) – coefficient derived from as1, bs1 for estimating clear-sky radiation [degrees].
as1 (float, optional) – regression constant, expressing the fraction of extraterrestrial reaching the earth on overcast days (n = 0) [-].
bs1 (float, optional) – empirical coefficient for extraterrestrial radiation [-].
clip_zero (bool, optional) – if True, replace all negative values with 0.
- Returns:
pandas.Series or xarray.DataArray containing the calculated pootential
evapotranspiration [mm d-1].
Examples
>>> pt = priestley_taylor(tmean, rn=rn, rh=rh)
Notes
\[PET = \frac{\alpha_{PT} \Delta (R_n-G)} {\lambda(\Delta +\gamma)}\]