Retrieval of xCO 2 from ground-based mid-infrared (NDACC) solar absorption spectra and comparison to TCCON

• Published in: Atmospheric Measurement Techniques
• Main Authors: M. Buschmann, N. M. Deutscher, V. Sherlock, M. Palm, T. Warneke, J. Notholt
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Publications 2016
• Subjects: Environmental engineering; TA170-171; Earthwork. Foundations; TA715-787; Ny-Ålesund; Ny Ålesund; Spitsbergen
• Online Access: https://doi.org/10.5194/amt-9-577-2016; https://doaj.org/article/b8f2532392e4429fae8c1c9b1b1e5964

High-resolution solar absorption spectra, taken within the Network for the Detection of Atmospheric Composition Change Infrared Working Group (NDACC-IRWG) in the mid-infrared spectral region, are used to infer partial or total column abundances of many gases. In this paper we present the retrieval of a column-averaged mole fraction of carbon dioxide from NDACC-IRWG spectra taken with a Fourier transform infrared (FTIR) spectrometer at the site in Ny-Ålesund, Spitsbergen. The retrieved time series is compared to colocated standard TCCON (Total Carbon Column Observing Network) measurements of column-averaged dry-air mole fractions of CO 2 (denoted by xCO 2 ). Comparing the NDACC and TCCON retrievals, we find that the sensitivity of the NDACC retrieval is lower in the troposphere (by a factor of 2) and higher in the stratosphere, compared to TCCON. Thus, the NDACC retrieval is less sensitive to tropospheric changes (e.g., the seasonal cycle) in the column average.