1UPMC Univ. Paris 06; Université Versailles St-Quentin; UMR8190, CNRS/INSU, LATMOS-IPSL, Paris, France
2Spectroscopie de l'Atmosphère, Chimie Quantique et Photophysique, Université Libre de Bruxelles (ULB),\newline Brussels, Belgium
3Department of Chemistry, University of York, Heslington, York, UK
4Université de Toulouse, UPS; CNRS, Laboratoire d'Aérologie (LA), Toulouse, France
5LSCE/IPSL, CEA-CNRS-UVSQ, Saclay, France
6NOAA ESRL Chemical Sciences Division, Boulder, Colorado, USA
7DLR, Institut für Physik der Atmosphäre, Oberpfaffenhofen, Germany
8NCAR, Boulder, USA
*now at: Air Quality Research Division, Science and Technology Branch,\newline Environment Canada, Toronto, Ontario, Canada
Received: 01 Dec 2011 – Discussion started: 16 Dec 2011
Abstract. Ozone data retrieved in the Arctic region from infrared radiance spectra recorded by the Infrared Atmospheric Sounding Interferometer (IASI) on board the MetOp-A European satellite are presented. They are compared with in situ and lidar observations obtained during a series of aircraft measurement campaigns as part of the International Polar Year POLARCAT activities in spring and summer 2008. Different air masses were sampled during the campaigns including clean air, polluted plumes originating from anthropogenic sources, forest fire plumes from the three northern continents, and stratospheric-influenced air masses. The comparison between IASI O3 [0–8 km], [0–12 km] partial columns and profiles with collocated aircraft observations is achieved by taking into account the different sensitivity and geometry of the sounding instruments. A detailed analysis is provided and the agreement is discussed in terms of vertical sensitivity and surface properties at the location of the observations. Overall, IASI O3 profiles are found to be in relatively good agreement with smoothed in situ and lidar profiles in the free troposphere with differences of less than 40% (25% over sea for both seasons) and 10%, respectively. The correlation between IASI O3 retrieved partial columns and the smoothed aircraft partial columns is good with DC-8 in situ data in spring over North America (r = 0.68), and over Greenland with ATR-42 lidar measurements in summer (r = 0.67). Correlations with other data are less significant highlighting the difficulty of IASI to capture precisely the O3 variability in the Arctic upper troposphere and lower stratosphere (UTLS). This is particularly noted in comparison with the [0–12 km] partial columns. The IASI [0–8 km] partial columns display a low negative bias (by less than 26% over snow) compared to columns derived from in situ measurements. Despite the relatively high biases of the IASI retrievals in the Arctic UTLS, our analysis shows that IASI can be used to identify, using O3 / CO ratios, stratospheric intrusions.
Revised: 17 Apr 2012 – Accepted: 12 Jul 2012 – Published: 16 Aug 2012
Pommier, M., Clerbaux, C., Law, K. S., Ancellet, G., Bernath, P., Coheur, P.-F., Hadji-Lazaro, J., Hurtmans, D., Nédélec, P., Paris, J.-D., Ravetta, F., Ryerson, T. B., Schlager, H., and Weinheimer, A. J.: Analysis of IASI tropospheric O3 data over the Arctic during POLARCAT campaigns in 2008, Atmos. Chem. Phys., 12, 7371-7389, doi:10.5194/acp-12-7371-2012, 2012.