Atmos. Chem. Phys. Discuss., 11, 31689-31734, 2011
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This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
Assimilation of IASI satellite CO fields into a global chemistry transport model for validation against aircraft measurements
A. Klonecki1, M. Pommier2,*, C. Clerbaux2,3, G. Ancellet2, J.-P. Cammas4, P.-F. Coheur3, A. Cozic5, G. S. Diskin6, J. Hadji-Lazaro2, D. A. Hauglustaine5, D. Hurtmans3, B. Khattatov7, J.-F. Lamarque7, K. S. Law2, P. Nedelec4, J.-D. Paris5, J. R. Podolske8, P. Prunet1, H. Schlager9, S. Szopa5, and S. Turquety10
1NOVELTIS, Ramonville-Saint-Agne, France
2UPMC Univ. Paris 06; Université Versailles St-Quentin; CNRS/INSU, LATMOS-IPSL, Paris, France
3Spectroscopie de l'Atmosphère, Chimie Quantique et Photophysique, Université Libre de Bruxelles (ULB), Brussels, Belgium
4UPS, Université de Toulouse; CNRS/INSU, LA (Laboratoire d'Aérologie), Toulouse, France
6NASA Langley Research Center, MS 483, Hampton, USA
7National Center for Atmospheric Research, Boulder, Colorado, USA
8NASA Ames Research Center, Moffett Field, California, 94035, USA
9DLR, Institut für Physik der Atmosphäre, Oberpfaffenhofen, Germany
10UPMC Univ. Paris 06; Ecole Polytechnique; CNRS UMR8539, LMD-IPSL, Palaiseau, France
*now at: Air Quality Research Division, Science and Technology Branch, Environment Canada, Toronto, Ontario, Canada

Abstract. A modelling system for assimilation of CO total columns measured by the IASI/MetOp was developed. The system, based on a sub-optimal Kalman filter coupled with the LMDz-INCA chemistry transport model, allows both assimilating long periods of historical data and making rapid forecasts of the CO concentrations in the middle troposphere based on latest available measurements. Tests of the forecast system were conducted during the international POLARCAT campaigns. A specific treatment that takes into account the representativeness of observations at the scale of the model grid is applied to the IASI CO columns and associated errors before their assimilation in the model. This paper presents the results of assimilation of eight months of historical satellite data measured in 2008. Comparisons of the assimilated CO profiles with independent in situ CO measurements from the MOZAIC program and the POLARCAT aircraft campaigns indicate that the assimilation leads to a considerable improvement of the model simulations in the middle troposphere as compared with a control run with no assimilation. Model biases in the simulation of background values are reduced and improvement in the simulation of very high concentrations is observed. The improvement is due to the transport by the model of the information present in the IASI CO retrievals. The consistency of the improvement contributes to the validation of the IASI CO data.

Citation: Klonecki, A., Pommier, M., Clerbaux, C., Ancellet, G., Cammas, J.-P., Coheur, P.-F., Cozic, A., Diskin, G. S., Hadji-Lazaro, J., Hauglustaine, D. A., Hurtmans, D., Khattatov, B., Lamarque, J.-F., Law, K. S., Nedelec, P., Paris, J.-D., Podolske, J. R., Prunet, P., Schlager, H., Szopa, S., and Turquety, S.: Assimilation of IASI satellite CO fields into a global chemistry transport model for validation against aircraft measurements, Atmos. Chem. Phys. Discuss., 11, 31689-31734, doi:10.5194/acpd-11-31689-2011, 2011.
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