The Ring effect — both in Fraunhofer lines and in the distortion caused to absorption values — is usually allowed for by using a radiative transfer program to simulate the effect and then using the resulting spectrum as a Ring 'pseudo-absorber' (that is, as though it were the absorption spectrum of a trace gas). This pseudo-absorption curve can then be fitted to the measured spectrum to remove the Ring effect.

The fitting process itself is illustrated in the section of this module dealing with the DOAS procedure. In the following steps we show the generation of a simplified Ring effect pseudo-absorber.

Note that in the real data analysis procedure the effect of Raman scattering is not approximated by a constant, c, as shown in this simulation, but is computed for each wavelength using a radiative transfer program.