Articles | Volume 8, issue 3
Atmos. Meas. Tech., 8, 1555–1573, 2015
Atmos. Meas. Tech., 8, 1555–1573, 2015

Research article 25 Mar 2015

Research article | 25 Mar 2015

Using XCO2 retrievals for assessing the long-term consistency of NDACC/FTIR data sets

S. Barthlott1, M. Schneider1, F. Hase1, A. Wiegele1, E. Christner1, Y. González2, T. Blumenstock1, S. Dohe1, O. E. García2, E. Sepúlveda2, K. Strong3, J. Mendonca3, D. Weaver3, M. Palm4, N. M. Deutscher4,6, T. Warneke4, J. Notholt4, B. Lejeune5, E. Mahieu5, N. Jones6, D. W. T. Griffith6, V. A. Velazco6, D. Smale7, J. Robinson7, R. Kivi8, P. Heikkinen8, and U. Raffalski9 S. Barthlott et al.
  • 1Institute for Meteorology and Climate Research (IMK-ASF), Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
  • 2Izaña Atmospheric Research Center, Agencia Estatal de Meteorología (AEMET), Tenerife, Spain
  • 3Department of Physics, University of Toronto (UofT), Toronto, Canada
  • 4Institute of Environmental Physics, University of Bremen (UB), Bremen, Germany
  • 5Institute of Astrophysics and Geophysics, University of Liège (ULG), Liège, Belgium
  • 6Centre for Atmospheric Chemistry, University of Wollongong (UOW), Wollongong, Australia
  • 7National Institute of Water and Atmospheric Research (NIWA), Lauder, New Zealand
  • 8Arctic Research, Finnish Meteorological Institute (FMI), Helsinki, Finland
  • 9The Swedish Institute of Space Physics (IRF), Kiruna, Sweden

Abstract. Within the NDACC (Network for the Detection of Atmospheric Composition Change), more than 20 FTIR (Fourier-transform infrared) spectrometers, spread worldwide, provide long-term data records of many atmospheric trace gases. We present a method that uses measured and modelled XCO2 for assessing the consistency of these NDACC data records. Our XCO2 retrieval setup is kept simple so that it can easily be adopted for any NDACC/FTIR-like measurement made since the late 1950s. By a comparison to coincident TCCON (Total Carbon Column Observing Network) measurements, we empirically demonstrate the useful quality of this suggested NDACC XCO2 product (empirically obtained scatter between TCCON and NDACC is about 4‰ for daily mean as well as monthly mean comparisons, and the bias is 25‰). Our XCO2 model is a simple regression model fitted to CarbonTracker results and the Mauna Loa CO2 in situ records. A comparison to TCCON data suggests an uncertainty of the model for monthly mean data of below 3‰. We apply the method to the NDACC/FTIR spectra that are used within the project MUSICA (multi-platform remote sensing of isotopologues for investigating the cycle of atmospheric water) and demonstrate that there is a good consistency for these globally representative set of spectra measured since 1996: the scatter between the modelled and measured XCO2 on a yearly time scale is only 3‰.