AMT Atmospheric Measurement Techniques AMT Atmos. Meas. Tech. 1867-8548 Copernicus Publications Göttingen, Germany 10.5194/amt-5-2843-2012 Retrieval of MetOp-A/IASI CO profiles and validation with MOZAIC data De Wachter E. 1 Barret B. 1 Le Flochmoën E. 1 Pavelin E. 2 Matricardi M. 3 Clerbaux C. 4 5 Hadji-Lazaro J. 4 George M. 4 Hurtmans D. 5 Coheur P.-F. 5 Nedelec P. 1 Cammas J. P. 1 Laboratoire d'Aérologie-OMP, Université de Toulouse – CNRS/INSU, UMR5560, Toulouse, France Met Office, Exeter, UK ECMWF, Reading, UK UPMC Univ. Paris 06; Université Versailles St-Quentin, CNRS/INSU – UMR8190, LATMOS-IPSL, Paris, France Spectroscopie de l'Atmosphère, Chimie Quantique et Photophysique, Université Libre de Bruxelles, Brussels, Belgium 26 11 2012 5 11 2843 2857 Copyright: © 2012 E. De Wachter et al. 2012 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://amt.copernicus.org/articles/5/2843/2012/amt-5-2843-2012.html The full text article is available as a PDF file from https://amt.copernicus.org/articles/5/2843/2012/amt-5-2843-2012.pdf

The IASI (Infrared Atmospheric Sounding Interferometer) nadir-looking thermal infrared sounder onboard MetOp-A enables the monitoring of atmospheric constituents on a global scale. This paper presents a quality assessment of IASI CO profiles retrieved by the two different retrieval algorithms SOFRID and FORLI, by an intercomparison with airborne in-situ CO profiles from the MOZAIC program for the 2008–2009 period. Lower (surface–480 hPa) and upper tropospheric partial column (480–225 hPa) comparisons as well as profile comparisons are made. The retrieval errors of the IASI products are less than 21% in the lower troposphere and less than 10% in the upper troposphere. A statistical analysis shows similar correlation coefficients for the two retrieval algorithms and smoothed MOZAIC of <i>r</i> ~ 0.8 and <i>r</i> ~ 0.7 in the lower and upper troposphere respectively. Comparison with smoothed MOZAIC data of the temporal variation of the CO profiles at the airports of Frankfurt and Windhoek demonstrates that the IASI products are able to capture the seasonal variability at these sites. At Frankfurt SOFRID (respectively FORLI) is positively biased by 10.5% (13.0%) compared to smoothed MOZAIC in the upper (lower) troposphere, and the limited sensitivity of the IASI instrument to the boundary layer when thermal contrast is low is identified. At Windhoek, the impact of the vegetation fires in Southern Africa from July to November is captured by both SOFRID and FORLI, with an overestimation of the CO background values (fire maxima) by SOFRID (FORLI) by 12.8% (10%). Profile comparisons at Frankfurt and Windhoek show that the largest discrepancies are found between the two IASI products and MOZAIC for the nighttime retrievals.

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