pyet.combination.kimberly_penman#
- pyet.combination.kimberly_penman(tmean, wind, 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, ea=None, albedo=0.23, kab=None, as1=0.25, bs1=0.5, clip_zero=True)[source]#
Potential evapotranspiration calculated according to Wright (1982).
- Parameters:
tmean (pandas.Series or xarray.DataArray) – average day temperature [°C].
wind (pandas.Series or xarray.DataArray) – mean day wind speed [m/s].
rs (pandas.Series or xarray.DataArray, optional) – incoming solar radiation [MJ m-2 d-1].
rn (pandas.Series or xarray.DataArray, optional) – net radiation [MJ m-2 d-1].
g (pandas.Series or int/xarray.DataArray, optional) – soil heat flux [MJ m-2 d-1].
tmax (pandas.Series or xarray.DataArray, optional) – maximum day temperature [°C].
tmin (pandas.Series or xarray.DataArray, optional) – minimum day temperature [°C].
rhmax (pandas.Series or xarray.DataArray, optional) – maximum daily relative humidity [%].
rhmin (pandas.Series or xarray.DataArray, optional) – mainimum daily relative humidity [%].
rh (pandas.Series or xarray.DataArray, optional) – mean daily relative humidity [%].
pressure (float 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 (pandas.Series or float, optional) – actual duration of sunshine [hour].
nn (pandas.Series or float, optional) – maximum possible duration of sunshine or daylight hours [hour].
rso (pandas.Series or float, 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 [-].
ea (float or pandas.Series or xarray.DataArray, optional) – actual vapor pressure [kPa].
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 potential
evapotranspiration [mm d-1].
Notes
Following Oudin et al. (2005).
\[PET = \frac{\Delta (R_n-G)+ \gamma (e_s-e_a) w} {\lambda(\Delta +\gamma)}\]\[w = u_2 * (0.4 + 0.14 * exp(-(\frac{J_D-173}{58})^2)) + (0.605 + 0.345 * exp(-(\frac{J_D-243}{80})^2))\]