Abstract
Abstract. Vertical profiles of the optical (extinction and backscatter coefficients, lidar ratio and Ångström exponent), microphysical (mean effective radius, mean refractive index, mean number concentration) and geometrical properties as well as the mass concentration of volcanic particles from the Eyjafjallajökull eruption were retrieved at selected heights over Athens, Greece, using multi-wavelength Raman lidar measurements performed during the period 21–24 April 2010. Aerosol Robotic Network (AERONET) particulate columnar measurements along with inversion schemes were initialized together with lidar observations to deliver the aforementioned products. The well-known FLEXPART (FLEXible PARTicle dispersion model) model used for volcanic dispersion simulations is initiated as well in order to estimate the horizontal and vertical distribution of volcanic particles. Compared with the lidar measurements within the planetary boundary layer over Athens, FLEXPART proved to be a useful tool for determining the state of mixing of ash with other, locally emitted aerosol types. The major findings presented in our work concern the identification of volcanic particles layers in the form of filaments after 7-day transport from the volcanic source (approximately 4000 km away from our site) from the surface and up to 10 km according to the lidar measurements. Mean hourly averaged lidar signals indicated that the layer thickness of volcanic particles ranged between 1.5 and 2.2 km. The corresponding aerosol optical depth was found to vary from 0.01 to 0.18 at 355 nm and from 0.02 up to 0.17 at 532 nm. Furthermore, the corresponding lidar ratios (S) ranged between 60 and 80 sr at 355 nm and 44 and 88 sr at 532 nm. The mean effective radius of the volcanic particles estimated by applying inversion scheme to the lidar data found to vary within the range 0.13–0.38 μm and the refractive index ranged from 1.39+0.009i to 1.48+0.006i. This high variability is most probably attributed to the mixing of aged volcanic particles with other aerosol types of local origin. Finally, the LIRIC (LIdar/Radiometer Inversion Code) lidar/sunphotometric combined inversion algorithm has been applied in order to retrieve particle concentrations. These have been compared with FLEXPART simulations of the vertical distribution of ash showing good agreement concerning not only the geometrical properties of the volcanic particles layers but also the particles mass concentration.
Highlights
The eruption of the Eyjafjallajökull volcano in Iceland (April and May 2010) created unprecedented disruption to the European air traffic, costing the aviation industry an estimated EUR 200 million per day (Harris et al, 2012)
In this paper we presented the vertical profiles of the optical, microphysical and geometrical properties as well as the mass concentration of volcanic particles from the Eyjafjallajökull eruption, as retrieved for selected heights using a multi-wavelength Raman lidar system and inverse models, during the first days of the arrival of the volcanic particles over Athens, Greece, in the period of 21–24 April 2010
The days of 21 and 22 April were characterized by the maximum presence of volcanic particles over Athens, with high finemode fractions in the total aerosol optical depth (AOD) (76.8 and 78.0 %, respectively) and quite high as the Ångström exponent (AE) values using collocated AERONET measurements and aerosol masking schemes
Summary
The eruption of the Eyjafjallajökull volcano in Iceland (April and May 2010) created unprecedented disruption to the European air traffic, costing the aviation industry an estimated EUR 200 million per day (Harris et al, 2012). Except the in situ airborne measurements, few other techniques could provide exact volcanic particle concentrations aloft One such technique that became very useful during the Eyjafjallajökull eruption is the laser remote sensing (lidar) technique, which is a very favorable tool for the direct monitoring of the vertical profile of the aerosol optical properties. The lidar technique was employed throughout Europe in the frame of the EARLINET project (Bösenberg et al, 2003) to monitor the volcanic particles plume dispersion – in time and space – over the European continent (Ansmann et al, 2010, 2012; Emeis et al, 2011; Gasteiger et al, 2011; Gross et al, 2012; Mona et al, 2012a; Papayannis et al, 2012; Revuelta et al, 2012; Rolf et al, 2012; Trickl et al, 2012; Wiegner et al, 2012; Navas-Guzmán et al, 2013; Pappalardo et al, 2013).
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
