Abstract
Abstract. During the eruption of Eyjafjallajökull in April–May 2010 multi-wavelength Raman lidar measurements were performed at the CNR-IMAA Atmospheric Observatory (CIAO), whenever weather conditions permitted observations. A methodology both for volcanic layer identification and accurate aerosol typing has been developed. This methodology relies on the multi-wavelength Raman lidar measurements and the support of long-term lidar measurements performed at CIAO since 2000. The aerosol mask for lidar measurements performed at CIAO during the 2010 Eyjafjallajökull eruption has been obtained. Volcanic aerosol layers were observed in different periods: 19–22 April, 27–29 April, 8–9 May, 13–14 May and 18–19 May. A maximum aerosol optical depth of about 0.12–0.13 was observed on 20 April, 22:00 UTC and 13 May, 20:30 UTC. Volcanic particles were detected at low altitudes, in the free troposphere and in the upper troposphere. Occurrences of volcanic particles within the PBL were detected on 21–22 April and 13 May. A Saharan dust event was observed on 13–14 May: dust and volcanic particles were simultaneously detected at CIAO at separated different altitudes as well as mixed within the same layer. Lidar ratios at 355 and 532 nm, the Ångström exponent at 355/532 nm, the backscatter-related Ångström exponent at 532/1064 nm and the particle linear depolarization ratio at 532 nm measured inside the detected volcanic layers are discussed. The dependence of these quantities on relative humidity has been investigated by using co-located microwave profiler measurements. The measured values of these intensive parameters indicate the presence of volcanic sulfates/continental mixed aerosol in the volcanic aerosol layers observed at CIAO. In correspondence of the maxima observed in the volcanic aerosol load on 19–20 April and 13 May, different values of intensive parameters were observed. Apart from the occurrence of sulfate aerosol, these values indicate also the presence of some ash which is affected by the aging during transport over Europe.
Highlights
Eyjafjallajokull, a small volcano under Iceland’s ice cap, entered an explosive eruptive phase on 14 April 2010 after an effusive period of approximately 6 weeks
EARLINET measurements were performed according to the alerts distributed by CNR-IMAA based on the model calculations of the ash dispersion provided by VAAC (Volcanic Ash Advisory Center) and EURAD (EURopean Air Pollution Dispersion)
The methodology described in the previous section is applied to all the periods identified as potentially affected by the volcanic cloud to the preliminary quick analysis of CNR-IMAA Atmospheric Observatory (CIAO) data: 19–22 April, 27–29 April, 8–9 May, 13–14 May www.atmos-chem-phys.net/12/2229/2012/
Summary
Eyjafjallajokull, a small volcano under Iceland’s ice cap, entered an explosive eruptive phase on 14 April 2010 after an effusive period of approximately 6 weeks. This mediumsized eruption (Petersen, 2010) caused an enormous disruption to air traffic across western and northern Europe, because it injected ash directly into the Jet Stream and from there in the northern Europe free troposphere. After Eyjafjallajokull’s first explosive eruption on 14 April 2010 the aerosol scientific community focused on the observation of the volcanic cloud. EARLINET, the European Aerosol Research Lidar NETwork, performed almost continuous measurements since 15 April 2010 in order to record the evolution of the volcanic cloud generated from the eruption. Between 15 April–26 May, the volcanic cloud was transported to different regions of continental Europe at different altitudes depending on the prevailing wind
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