The error on the wavelengths. Cross-sections of ozone and its temperature dependence. Instrument characteristics, e.g FWHM and shape of slit function. Especially the RTM sets the speed and accuracy. Since the inversion problem of computing an ozone profile from an earthshine spectrum is under-constrained, the end product is sensitive to error amplification.
Great care is therefore mandatory to select a suitable inversion method.
Optimal estimation stabilizes the solution against error amplification. It is not expected that the selection of this method will induce any non-negligible contribution to the accuracy of the ozone profile. Unfortunately, this most interesting region for measuring ozone suffers from the occurrence of high solar zenith angles. This has three effects on the quality and speed of the ozone profile retrieval. The effect of low ozone amounts is not an important factor for the performance.