Atmos. Chem. Phys. Discuss., 12, 31031-31070, 2012
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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.
Detection and characterization of volcanic ash plumes over Lille during the Eyjafjallajökull eruption
A. Mortier1, P. Goloub1, T. Podvin1, C. Deroo1, A. Chaikovsky2, N. Ajtai3, L. Blarel1, D. Tanre1, and Y. Derimian1
1Laboratoire d'Optique Atmosphérique, CNRS-UMR8518, Université Lille 1, Villeneuve d'Ascq, France
2Laboratory of Optics of Scattering Media, Stepanov Institute, Academy of science of Belarus, Minsk, Belarus
3Research Center for Disaster Management , Faculty of Environmental Science and Engineering, Babeş-Bolyai University, Cluj-Napoca, Romania

Abstract. Routine sun-photometer and micro-LIDAR measurements were performed in Lille, northern France, in April and May 2010 during the Eyjafjallajökull volcanic eruption. The impact of such an eruption emphasized significance of hazards for human activities and importance of observarions of the volcanic aerosol particles. This paper presents the main results of a joint micro-LIDAR/sun-photometer analysis performed in Lille, where volcanic ash plumes were observed during at least 22 days, weather conditions permitting. Aerosol properties retrieved from automatic sun-photometer measurements (AERONET) were strongly changed during the volcanic aerosol plumes transport over Lille. In most cases, the Aerosol Optical Depth (AOD) was increased whereas Ångström exponent decreased thus indicating coarse mode dominance in the volume size distribution. Moreover, the retrieved by AERONET non spherical fraction was significantly increased. The Real part of the complex refractive index was up to 1.55 at 440 nm during the eruption time while typically was about 1.46 before the eruption. Collocated LIDAR data revealed that several aerosol layers were present between 2 and 5 km, all originating from Iceland region as confirmed by backward-trajectories. The volcanic ash AOD was derived from LIDAR extinction profiles and sun-photometer AOD, and was estimated of around 0.37 at 532 nm on 18 April 2010. This value was observed at an altitude of 1700 m and corresponded to an Ash Mass Concentration (AMC) slightly higher than 1000 μg m3 (±50%). The effective LIDAR Ratio of ash particles was 48 sr for 18 April during the early stages of the eruption, a value which agrees with several other studies carried out on this topic. Even though the accuracy of the retrievals is not as high as that obtained from reference multi-wavelength LIDAR systems, this study demonstrates the opportunity of micro-LIDAR and sun-photometer joint data processing for deriving volcanic AMC. It also outlines the fact that a network of combined micro-LIDARs and sun-photometers can be a powerful tool for routine monitoring of aerosols, especially in case of such hazardous volcanic events.

Citation: Mortier, A., Goloub, P., Podvin, T., Deroo, C., Chaikovsky, A., Ajtai, N., Blarel, L., Tanre, D., and Derimian, Y.: Detection and characterization of volcanic ash plumes over Lille during the Eyjafjallajökull eruption, Atmos. Chem. Phys. Discuss., 12, 31031-31070, doi:10.5194/acpd-12-31031-2012, 2012.
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