A new data processing method of differential optical absorption spectrum for measuring atmospheric trace gases

摘要

Differential optical absorption spectroscopy (DOAS) is the method widely used to measure trace gases in the atmosphere. The key procedures in the retrieval algorithms of the recorded DOAS spectra are the separation of the absorption into two parts that represent respectively broad and narrow spectral features and the evaluation of absorption spectra. The linear least-squares fitting routines were used to evaluate absorption spectra in the past when the atmospheric spectra were modeled with a linear combination of known laboratory reference spectra to derive the concentrations. In this paper, a new analysis method to derive the concentrations was developed. The method is based on the data correlation and can get the simultaneous linear equations with unknowns of the concentrations c_1, c_2, ... c_n. Solving this n order linear equations can determinate the concentrations of trace gases. This new method considers the fingerprint features of the various trace gases in the same range of wavelength and reduces the influence caused by the detector noise and photon statistics.