Assimilation of IASI satellite CO fields into a global chemistry transport model for validation against aircraft measurements

A. Klonecki (1) , Matthieu Pommier (2, 3) , Cathy Clerbaux (4, 3) , Gérard Ancellet (3) , Jean-Pierre Cammas (5) , Pierre-François Coheur (4) , Anne Cozic (6, 7) , G. S. Diskin (8) , Juliette Hadji-Lazaro (3) , Didier A. Hauglustaine (6, 9) , Daniel Hurtmans (4) , B. Khattatov (10) , J.-F. Lamarque (10) , Kathy S. Law (3) , Philippe Nedelec (5) , Jean-Daniel Paris (6, 11) , J. R. Podolske (12) , P. Prunet (1) , H. Schlager (13) , Sophie Laval-Szopa (6, 14) , Solène Turquety (15, 16)

1 NOVELTIS [Sté]
2 Air Quality Research Division [Toronto]
3 TROPO - LATMOS
4 Spectroscopie de l'atmosphère, Service de Chimie Quantique et Photophysique
5 LAERO - Laboratoire d'aérologie
6 LSCE - Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette]
7 CALCULS - Calcul Scientifique
8 LaRC - NASA Langley Research Center [Hampton]
9 MERMAID - Modelling the Earth Response to Multiple Anthropogenic Interactions and Dynamics
10 NCAR - National Center for Atmospheric Research [Boulder]
11 ICOS-RAMCES - ICOS-RAMCES
12 ARC - NASA Ames Research Center
13 IPA - DLR Institut für Physik der Atmosphäre = DLR Institute of Atmospheric Physics
14 CLIM - Modélisation du climat
15 UPMC - Université Pierre et Marie Curie - Paris 6
16 LMD - Laboratoire de Météorologie Dynamique (UMR 8539)

This work evaluates the IASI CO product against independent in-situ aircraft data from the MOZAIC program and the POLARCAT aircraft campaign. The validation is carried out by analysing the impact of assimilation of eight months of IASI CO columns retrieved for the period of May to December 2008 into the global chemistry transport model LMDz-INCA. A modelling system based on a sub-optimal Kalman filter was developed and 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. Comparisons of the assimilated CO profiles with in situ CO measurements 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. Our analysis also shows the impact of assimilation of CO on the representation of transport into the Arctic region during the POLARCAT summer campaign. A considerable increase in CO mixing ratios over the Asian source region was observed when assimilation was used leading to much higher values of CO during the cross-pole transport episode. These higher values are in good agreement with data from the POLARCAT flights that sampled this plume.

Domaines: Physique Atmosphérique et Océanique [physics.ao-ph]; Milieux et Changements globaux

A. Klonecki, Matthieu Pommier, Cathy Clerbaux, Gérard Ancellet, Jean-Pierre Cammas, et al.. Assimilation of IASI satellite CO fields into a global chemistry transport model for validation against aircraft measurements. Atmospheric Chemistry and Physics, 2012, 12 (10), pp.4493-4512. ⟨10.5194/acp-12-4493-2012⟩. ⟨hal-00647994⟩