Solar direct flux

PyAstronomy.pyasl.solarDirectFluxMeinel(z, height=0.0, I0=1353, c=0.357, s=0.678, a=0.14)

Direct (unscattered) solar flux in the Earth’s atmosphere according to Meinel 1976.

The height-dependent flux of direct solar radiation was given by Meinel & Meinel `` Applied Solar Energy’’ (Addison Wesley Publishing Co., 1976) on page 46 as

\[I_0 \left( (1-ah) \exp(-c \times A(z)^s) + ah \right)\]

where \(A(z)\) is the airmass (evaluated via airmassPP() using the plane parallel approximation)

Parameters
zfloat or array

The zenith angle [deg]

heightfloat

The height above ground [km]

I0float, optional

Solar constant (W/m**2)

cfloat, optional

Coefficient

sfloat, optional

Coefficient

afloat, optional

Coefficient

Returns
Direct fluxfloat or array

Direct solar flux in W/m**2 facing the Sun

Example

from PyAstronomy import pyasl
import numpy as np
import matplotlib.pylab as plt

z = np.linspace(0,89.9,200)

for h in [0,2,4]:

    f = pyasl.solarDirectFluxMeinel(z, height=h)

    plt.plot(z, f, '-', label=f"Height = {h} km")

plt.legend()
plt.xlabel("Zenith angle [deg]")
plt.ylabel("Direct solar flux [W/m**2]")
plt.show()