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Journal of Spectroscopy
Volume 2015, Article ID 736382, 9 pages
http://dx.doi.org/10.1155/2015/736382
Research Article

Retrieval of Atmospheric CO2 and CH4 Variations Using Ground-Based High Resolution Fourier Transform Infrared Spectra

1Key Lab of Environmental Optics & Technology, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China
2University of Science and Technology of China, Hefei 230026, China

Received 23 June 2015; Accepted 31 August 2015

Academic Editor: Arnaud Cuisset

Copyright © 2015 Tian Yuan et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

High resolution Fourier transform near IR solar spectra are used to estimate the column-averaged dry-air mole fraction (DMF) of CO2 and variations in the atmosphere. The preliminary retrieval results for CO2 and variations in the area of Hefei, China, are presented, and the underlying error sources are also analyzed. Both a forward analysis and an inversion algorithm are included in the retrieval. The forward analysis uses the modeled atmospheric transmittance to line-by-line (LBL) convolute the instrument line shape function. The influences of the temperature, pressure, humidity, and a priori gases are considered in the atmospheric transmittance model. The inversion algorithm is based on the nonlinear iterative and nonlinear least squares spectral fitting, which is used to obtain and (which represent vertical column density of CO2 and , resp.). Furthermore, the is also retrieved for converting the VCDs into DMFs. DMFs are final products of data analysis. The inversion results can clearly resolve the tiny variations of CO2 and under strong atmospheric background. Spectral fitting residuals for both and are less than 0.5%. Finally, CO2 and diurnal variations are investigated based on a typical observation. About 2 ppm amplitude for diurnal variations and less than 15 ppb amplitude for are observed.