In spectroscopy and radiometry, vector radiative transfer (VRT) is a method of modelling the propagation of polarized electromagnetic radiation in low density media.
, the VRT equation for a scattering media can be written as follows: where s is the path,
is the absorption vector, B is the Planck function and Z is the scattering phase matrix.
and Z, will vary depending on the density of absorbers/scatterers present and must be calculated from their density-independent quantities, that is the attenuation coefficient vector,
, is calculated from the mass absorption coefficient vector times the density of the absorber.
Extinction is caused both by simple absorption as well as from scattering out of the line-of-sight,
where I, Q, U and V are the first through fourth elements of the Stokes parameters, respectively, fully describes the polarization state of the electromagnetic radiation.