Radiative Transfer Equation (IR)

B_i(T) is the Planck function evaluated at the effective channel wavenumber.
H_i is the channel averaged solar irradiance at the top of the atmosphere.
₀ is the local zenith angle of the Sun.
'_i is the channel averaged two path transmittance from the Sun to the surface to the satellite.
^u_i(p) is the atmospheric transmittance measured between p and the top of the atmosphere for channel i.
^d_i(p) is the atmospheric transmittance between p and the surface for channel i.

Explicit retrieved parameters
_i is the surface emissivity at _i.
T_s is the surface temperature.
T(p) is the surface temperature profile.
_i is the surface spectral reflectivity at _i.
'_i is the surface spectral bidirectional reflectance of solar radiation at _i.

Implicit retrieved parameters ( i.e., within _i and '_i).
CO₂(p) is the carbon dioxide profile.
q(p) is the humidity (water) profile.
O₃(p) is the ozone profile.
CO(p) is the carbon monoxide profile.
CH₄(p) is the methane profile.
NO₂(p) is the nitrogen dioxide profile.