pyet.rad_utils.calc_rad_long

pyet.rad_utils.calc_rad_long(rs, tmean=None, tmax=None, tmin=None, rhmax=None, rhmin=None, rh=None, elevation=None, lat=None, rso=None, a=1.35, b=-0.35, ea=None, kab=None)

Net longwave radiation [MJ m-2 d-1].

Parameters:

• rs (float or pandas.Series or xarray.DataArray, optional) – incoming solar radiation [MJ m-2 d-1].

• tmean (float or pandas.Series or xarray.DataArray, optional) – average day temperature [°C].

• 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 [%].

• elevation (float/xarray.DataArray, optional) – the site elevation [m].

• lat (float/xarray.DataArray, optional) – the site latitude [rad].

• 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 [-].

• ea (float or pandas.Series or xarray.DataArray, optional) – actual vapor pressure [kPa].

• kab (float, optional) – coefficient that can be derived from the as and bs coefficients of the Angstrom formula, where Kab = as + bs, and where Kab represents the fraction of extraterrestrial radiation reaching the earth on clear-sky days [-].

Returns:

• float or pandas.Series or xarray.DataArray, optional containing the calculated net

• longwave radiation.

Notes

Based on equation 39 in Allen et al. (1998).