Near-infrared radiative transfer modelling with different CH4 spectroscopic databases to retrieve atmospheric methane total amount

Atmospheric methane content can be retrieved from measurements of solar radiation attenuated by the atmosphere in the near infrared spectral region where the space-borne and ground-based spectrometers carry out regular measurements. It is shown, in the present work, that the different spectroscopic databases can give significantly different results for both forward simulations of the atmospheric transmittance and the inverse problem solution to retrieve the CH4 total content in the atmosphere using spectra measured by ground-based FTIR spectrometer in the near infrared spectral region. These discrepancies and the problem of the reduction of their influence on the atmospheric radiation transfer calculations are discussed. A comparison of atmospheric ground-based measured and simulated spectra, modelled with different CH4 databases, is presented.

► Accuracy of CH4 concentration retrieval from atmospheric spectra depends on absorption line parameters. ► A comparison of atmospheric ground-based measured and spectra, modelled with different CH4 spectroscopic databases, is made. ► Differences between the atmospheric methane total contents, retrieved with different CH4 databanks, can exceed 5%.