Atmos. Chem. Phys. Discuss., 12, 6623-6653, 2012
www.atmos-chem-phys-discuss.net/12/6623/2012/
doi:10.5194/acpd-12-6623-2012
© Author(s) 2012. This work is distributed
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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.
French airborne lidar measurements for Eyjafjallajökull ash plume survey
P. Chazette1, A. Dabas2, J. Sanak1, M. Lardier3, and P. Royer1,3
1Laboratoire des Sciences du Climat et de l'Environnement (LSCE), UMR8212, CNRS – Laboratoire mixte CEA-CNRS-UVSQ, CEA Saclay, 91191 Gif-sur-Yvette, France
2Groupe d'Etude de l'Atmosphère Météorologique, URA Météo-France/CNRS, 42 avenue Coriolis, 31100 Toulouse, France
3LEOSPHERE, 76 rue de Monceau, 75008 Paris, France

Abstract. An Ultra-Violet Rayleigh-Mie lidar has been integrated aboard the French research aircraft Falcon 20 in order to monitor the ash plume emitted by the Eyjafjallajökul volcano in April–May 2010. Three operational flights were carried out on 21 April, 12 and 16 May 2010 inside French, Spanish and British air spaces, respectively. The original purpose of the flights was to provide the French civil aviation authorities with objective information on the presence and location of the ash plume. The present paper presents the results of detailed analyses elaborated after the volcano crisis. They bear on the structure of the ash clouds and their optical properties such as ash extinction coefficient and lidar ratio. Lidar ratios were measured in the range of 33 to 48 sr, in good agreement with the ratios derived from ground-based lidar measurements performed near Paris (France) in April 2010 (∼47 sr). The ash signature in terms of particulate depolarization was consistent around 45 ± 7% during all flights. Such a value seems to be a good identification parameter for ash. Using specific cross-sections between 0.29 and 1.1 m2 g−1, the minimum (maximal) mass concentrations in the ash plumes are derived for the flights on 12 and 16 May. They were 190 (2300) and 270 (1600) μg m−3, respectively. It may be rather less than, or of the order of the critical level of damage (2 mg m−3) for the aircraft engines, but well above the 200 μg m−3 warning level.

Citation: Chazette, P., Dabas, A., Sanak, J., Lardier, M., and Royer, P.: French airborne lidar measurements for Eyjafjallajökull ash plume survey, Atmos. Chem. Phys. Discuss., 12, 6623-6653, doi:10.5194/acpd-12-6623-2012, 2012.
 
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