Integration of measurements and model simulations to characterize Eyjafjallajökull volcanic aerosols over south-eastern Italy

M R Perrone,N I Kristiansen,A Stohl,F De Tomasi

doi:10.5194/acp-12-10001-2012

M R Perrone, N I Kristiansen + Show 2 more

Open Access

https://doi.org/10.5194/acp-12-10001-2012

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Abstract

Abstract. Volcanic aerosols resulting from the Eyjafjallajökull eruption were detected in south-eastern Italy from 20 to 22 April 2010, at a distance of approximately 4000 km from the volcano, and have been characterized by lidar, sun/sky photometer, and surface in-situ measurements. Volcanic particles added to the pre-existing aerosol load and measurement data allow quantifying the impact of volcanic particles on the aerosol vertical distribution, lidar ratios, the aerosol size distribution, and the ground-level particulate-matter concentrations. Lidar measurements reveal that backscatter coefficients by volcanic particles were about one order of magnitude smaller over south-eastern Italy than over Central Europe. Mean lidar ratios at 355 nm were equal to 64 ± 5 sr inside the volcanic aerosol layer and were characterized by smaller values (47 ± 2 sr) in the underlying layer on 20 April, 19:30 UTC. Lidar ratios and their dependence with the height reduced in the following days, mainly because of the variability of the volcanic particle contributions. Size distributions from sun/sky photometer measurements reveal the presence of volcanic particles with radii r > 0.5 μm on 21 April and that the contribution of coarse volcanic particles increased from 20 to 22 April. The aerosol fine mode fraction from sun/sky photometer measurements varied between values of 0.85 and 0.94 on 20 April and decreased to values between 0.25 and 0.82 on 22 April. Surface measurements of particle size distributions were in good accordance with column averaged particle size distributions from sun/sky photometer measurements. PM1/PM2.5 mass concentration ratios of 0.69, 0.66, and 0.60 on 20, 21, and 22 April, respectively, support the increase of super-micron particles at ground. Measurements from the Regional Air Quality Agency show that PM10 mass concentrations on 20, 21, and 22 April 2010 were enhanced in the entire Apulia Region. More specifically, PM10 mass concentrations have on average increased over Apulia Region 22%, 50%, and 28% on 20, 21, and 22 April, respectively, compared to values on 19 April. Finally, the comparison of measurement data with numerical simulations by the FLEXPART dispersion model demonstrates the ability of FLEXPART to model the advection of the volcanic ash over the 4000 km from the Eyjafjallajökull volcano to Southern Italy.

Highlights

The eruption of the Eyjafjallajokull volcano in Iceland entered a phase of strong ash ejection to the atmosphere on 14 April 2010, which lasted for several days
Eight-day analytical back trajectories from the Hybrid Single Particle Lagrangian Integrated Trajectory Model (HYSPLIT) (Draxler and Rolph, 2010) have been analyzed in this study to infer the arrival of volcanic particles over Lecce
The back trajectories ending at ∼ 2 and 3 km a.s.l. originated over Central Europe. They had travelled over European regions known to have been affected by volcanic ash before reaching Lecce, and as a consequence may have been responsible for the advection of volcanic particles at altitudes larger than few kms a.s.l

Summary

Introduction

The eruption of the Eyjafjallajokull volcano in Iceland entered a phase of strong ash ejection to the atmosphere on 14 April 2010, which lasted for several days. The volcanic ash was detected in clear layers above Switzerland starting from 17 April (Bukowiecki et al, 2011), above southern Italy from 19 April (Madonna et al, 2010; Mona et al, 2012), and over Greece after 21 April (Papayannis et al, 2012). Different ground-based, airborne and space-borne instruments have been used to characterize the physical and optical properties of the volcanic aerosols resulting from the Eyjfjallajokull eruption (e.g. Bukowiecki et al, 2011; Schafer et al, 2011; Revuelta et al, 2012; Campanelli et al, 2012; Schumann et al, 2011, Toledano et al, 2012; Rossini et al, 2012). This paper focuses firstly on the integration of different measurements techniques to characterize aged volcanic aerosols at Lecce (40.4◦ N; 18.1◦ E), in south-eastern Italy, approximately 4000 km away from the Eyjafjallajokull volcano.

Experimental devices

The FLEXPART dispersion model

The advection of volcanic aerosols to south-eastern Italy

UNILE lidar measurements

Measurements and FLEXPART simulations

Summary and conclusion