varwg.meteo.meteox2y.iziomon

varwg.meteo.meteox2y.iziomon(temp, clouds, rh=None, dew=None, e=None, site='low')

incident long wave radiation following Iziomon et al (2003)[R6331e1085f99-1]_

As input is required: air temperature (temp), cloud cover (clouds) and EITHER relative humidity (rh) OR dewpoint (dew) OR vapour pressure (e).

Parameters:

tempfloat or numpy.array of floats

air temperature [deg C]

cloudsfloat or numpy.array of floats

cloud cover with values between 0 and 1 [-]

rhfloat or numpy.array of floats or None

relative humidity with values between 0 and 1 [-]

dewfloat or numpy.array of floats or None

dewpoint [deg C]

efloat or numpy.array of floats or None

vapour pressure [hPa]

site{‘low’, ‘high’}

parameterisation for lowland or highland site

Returns:

lwfloat or numpy.array of floats

incident longwave radiation [W/m**2]

See also

lw2clouds

reverse (get cloud cover out of long wave, temperature and humidity)

Notes

Empirical formula, found for experiments in Bremgarten (47deg54’35’’N; 7deg37’18’’E) in the Upper Rhine plain in Germany (lowland site) and Feldberg, 1489 m asl, 47deg52’31’’N, 8deg00’11’’E, Black Forest, Germany (highland site)

References

[1]

Iziomon, M.G., Mayer H, Matzarakis A. (2003): Downward atmospheric longwave irradiance under clear and cloudy skies: Measurement and parameterization, Journal of Atmospheric and Solar-Terrestrial Physics 65 (2003) 1107 - 1116

Examples

>>> iziomon(15.,0.5,rh=0.89)
327.52426791875763

>>> temp = np.array((0.0, 2.5, 5.0, 7.5, 10.0))
>>> clouds = np.array((0.0, 0.1, 0.8, 0.5, 1.0))
>>> e = np.array((5.5, 5.8, 6.1, 6.2, 6.3))
>>> iziomon(temp,clouds,e=e)
array([225.34414848,  235.0777488 ,  279.01405432,  267.25348612,
        321.15448959])