ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-5-2901-2005 Global carbon monoxide vertical distributions from spaceborne high-resolution FTIR nadir measurements Barret B. 1 4 Turquety S. 2 5 Hurtmans D. 1 Clerbaux C. 1 2 Hadji-Lazaro J. 2 Bey I. 3 Auvray M. 3 Coheur P.-F. 1 Service de Chimie Quantique et Photophysique, Université Libre de Bruxelles, Bruxelles, Belgium Service d’Aéronomie, Institut Pierre-Simon Laplace, Paris, France Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland now at: Laboratoire d’Aérologie, CNRS, Toulouse, France now at: Division of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, USA 02 11 2005 5 11 2901 2914 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.atmos-chem-phys.net/5/2901/2005/acp-5-2901-2005.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/5/2901/2005/acp-5-2901-2005.pdf

This paper presents the first global distributions of CO vertical profiles retrieved from a thermal infrared FTS working in the nadir geometry. It is based on the exploitation of the high resolution and high quality spectra measured by the Interferometric Monitor of Greenhouse gases (IMG) which flew onboard the Japanese ADEOS platform in 1996-1997. The retrievals are performed with an algorithm based on the Optimal Estimation Method (OEM) and are characterized in terms of vertical sensitivity and error budget. It is found that most of the IMG measurements contain between 1.5 and 2.2 independent pieces of information about the vertical distribution of CO from the lower troposphere to the upper troposphere-lower stratosphere (UTLS). The retrievals are validated against coincident NOAA/CMDL in situ surface measurements and NDSC/FTIR total columns measurements. The retrieved global distributions of CO are also found to be in good agreement with the distributions modeled by the GEOS-CHEM 3D CTM, highlighting the ability of IMG to capture the horizontal as well as the vertical structure of the CO distributions.