Numerical analysis and estimation of the statistical error of differential optical absorption spectroscopy measurements with least-squares methods

Abstract

Differential optical absorption spectroscopy (DOAS) has become a widely used method to measure trace gases in the atmosphere. Their concentration is retrieved by a numerical analysis of the atmospheric absorption spectra, which often are a combination of overlapping absorption structures of several trace gases. A new analysis procedure was developed, modeling atmospheric spectra with the absorption structures of the individual trace gases, to determine their concentrations. The procedure also corrects differences in the wavelength–pixel mapping of these spectra. A new method to estimate the error of the concentrations considers the uncertainty of this correction and the influence of random residual structures in the absorption spectra.