Published under the terms of the Creative Commons Attribution-Noncommercial 3.0 Unported LicenseVertical profiles of the linear particle depolarization ratio of pure dust clouds were measured during the Saharan Mineral Dust Experiment (SAMUM) at Ouarzazate, Morocco (30.9 degrees N, -6.9 degrees E), close to source regions in May-June 2006, with four lidar systems at four wavelengths (355, 532, 710 and 1064 nm). The intercomparison of the lidar systems is accompanied by a discussion of the different calibration methods, including a new, advanced method, and a detailed error analysis. Over the whole SAMUM periode pure dust layers show a mean linear particle depolarization ratio at 532 nm of 0.31, in the range between 0.27 and 0.35, with a mean angstrom ngstrom exponent (AE, 440-870 nm) of 0.18 (range 0.04-0.34) and still high mean linear particle depolarization ratio between 0.21 and 0.25 during periods with aerosol optical thickness less than 0.1, with a mean AE of 0.76 (range 0.65-1.00), which represents a negative correlation of the linear particle depolarization ratio with the AE. A slight decrease of the linear particle depolarization ratio with wavelength was found between 532 and 1064 nm from 0.31 +/- 0.03 to 0.27 +/- 0.04

Abstract. Airborne lidar and in-situ measurements of aerosols and trace gases were performed in volcanic ash plumes over Europe between Southern Germany and Iceland with the Falcon aircraft during the eruption period of the Eyjafjalla 1 volcano between 19 April and 18 May 2010. Flight planning and measurement analyses were supported by a refined Meteosat ash product and trajectory model analysis. The volcanic ash plume was observed with lidar directly over the volcano and up to a distance of 2700 km downwind, and up to 120 h plume ages. Aged ash layers were between a few 100 m to 3 km deep, occurred between 1 and 7 km altitude, and were typically 100 to 300 km wide. Particles collected by impactors had diameters up to 20 µm diameter, with size and age dependent composition. Ash mass concentrations were derived from optical particle spectrometers for aCorrespondence to: U. Schumann (ulrich.schumann@dlr.de) 1 Also known as Eyjafjallajökull or Eyjafjöll volcano, http://www.britannica.com/EBchecked/topic/1683937/ Eyjafjallajokull-volcano particle density of 2.6 g cm −3 and various values of the refractive index (RI, real part: 1.59; 3 values for the imaginary part: 0, 0.004 and 0.008). The mass concentrations, effective diameters and related optical properties were compared with ground-based lidar observations. Theoretical considerations of particle sedimentation constrain the particle diameters to those obtained for the lower RI values. The ash mass concentration results have an uncertainty of a factor of two. The maximum ash mass concentration encountered during the 17 flights with 34 ash plume penetrations was below 1 mg m −3 . The Falcon flew in ash clouds up to about 0.8 mg m −3 for a few minutes and in an ash cloud with approximately 0.2 mg m −3 mean-concentration for about one hour without engine damage. The ash plumes were rather dry and correlated with considerable CO and SO 2 increases and O 3 decreases. To first order, ash concentration and SO 2 mixing ratio in the plumes decreased by a factor of two within less than a day. In fresh plumes, the SO 2 and CO concentration increases were correlated with the ash mass concentration. The ash plumes were often visible slantwise as faint dark layers, even for concentrations below 0.1 mg m −3 .Published by Copernicus Publications on behalf of the European Geosciences Union. U. Schumann et al.: Airborne observations of the Eyjafjalla volcano ash cloud over EuropeThe large abundance of volatile Aitken mode particles suggests previous nucleation of sulfuric acid droplets. The effective diameters range between 0.2 and 3 µm with considerable surface and volume contributions from the Aitken and coarse mode aerosol, respectively. The distal ash mass flux on 2 May was of the order of 500 (240-1600) kg s −1 . The volcano induced about 10 (2.5-50) Tg of distal ash mass and about 3 (0.6-23) Tg of SO 2 during the whole eruption period. The results of the Falcon flights were used to support the responsible agencies in their decisions concerning air traffic in the presence of v...

Abstract. The European Aerosol Research Lidar Network, EARLINET, was founded in 2000 as a research project for establishing a quantitative, comprehensive, and statistically significant database for the horizontal, vertical, and temporal distribution of aerosols on a continental scale. Since then EARLINET has continued to provide the most extensive collection of ground-based data for the aerosol vertical distribution over Europe. This paper gives an overview of the network's main developments since 2000 and introduces the dedicated EAR-LINET special issue, which reports on the present innovative and comprehensive technical solutions and scientific results related to the use of advanced lidar remote sensing techniques for the study of aerosol properties as developed within the network in the last 13 years.Since 2000, EARLINET has developed greatly in terms of number of stations and spatial distribution: from 17 stations in 10 countries in 2000 to 27 stations in 16 countries in 2013. EARLINET has developed greatly also in terms of technological advances with the spread of advanced multiwavelength Raman lidar stations in Europe. The developments for the quality assurance strategy, the optimization of instruments and data processing, and the dissemination of data have contributed to a significant improvement of the network towards a more sustainable observing system, with an increase in the observing capability and a reduction of operational costs.Consequently, EARLINET data have already been extensively used for many climatological studies, long-range transport events, Saharan dust outbreaks, plumes from volcanic eruptions, and for model evaluation and satellite data validation and integration.Future plans are aimed at continuous measurements and near-real-time data delivery in close cooperation with other ground-based networks, such as in the ACTRIS (Aerosols, Clouds, and Trace gases Research InfraStructure Network) www.actris.net, and with the modeling and satellite community, linking the research community with the operational world, with the aim of establishing of the atmospheric part of the European component of the integrated global observing system.

More than 130 observation days of the horizontal and vertical extent of Saharan dust intrusions over Europe during the period May 2000 to December 2002 were studied by means of a coordinated lidar network in the frame of the European Aerosol Research Lidar Network (EARLINET). The number of dust events was greatest in late spring, summer, and early autumn periods, mainly in southern (S) and southeastern (SE) Europe. Multiple aerosol dust layers of variable thickness (300–7500 m) were observed. The center of mass of these layers was located in altitudes between 850 and 8000 m. However, the mean thickness of the dust layer typically stayed around 1500–3400 m and the corresponding mean center of mass ranged from 2500 to 6000 m. In exceptional cases, dust aerosols reached northwestern (NW), northern (N), or northeastern (NE) Europe, penetrating the geographical area located between 4°W–28°E (longitude) and 38°N–58°N (latitude). Mean aerosol optical depths (AOD), extinction-to-backscatter ratios (lidar ratios, LR), and linear depolarization ratios of desert aerosols ranged from 0.1 to 0.25 at the wavelength of 355 or 351 nm, 30 to 80 sr at 355 or 351 nm, and 10 to 25% at 532 nm, respectively, within the lofted dust plumes. In these plumes typical Saharan dust backscatter coefficients ranged from 0.5 to 2 Mm−1sr−1. Southern European stations presented higher variability of the LR values and the backscatter-related Ångström exponent values (BRAE) (LR: 20–100 sr; BRAE: −0.5 to 3) than northern ones (LR: 30–80 sr; BRAE: −0.5 to 1)

[1] A combined lidar-photometer method that permits the retrieval of vertical profiles of ash and non-ash (fine-mode) particle mass concentrations is presented. By using a polarization lidar, the contributions of non-ash and ash particles to total particle backscattering and extinction are separated. Sun photometer measurements of the ratio of particle volume concentration to particle optical thickness (AOT) for fine and coarse mode are then used to convert the non-ash and ash extinction coefficients into respective fine-mode and ash particle mass concentrations. The method is applied to European Aerosol Research Lidar Network (EARLINET) and Aerosol Robotic Network (AERONET) Sun photometer observations of volcanic aerosol layers at Cabauw, Netherlands, and Hamburg, Munich, and Leipzig, Germany, after the strong eruptions of the Icelandic Eyjafjallajökull volcano in April and May 2010. A consistent picture in terms of photometer-derived fine-and coarse-mode AOTs and lidar-derived non-ash and ash extinction profiles is found. The good agreement between the fine-to coarse-mode AOT ratio and non-ash to ash AOT ratio (<10% difference) in several cases corroborates the usefulness of the new retrieval technique. The main phases of the evolution of the volcanic aerosol layers over central Europe from 16 April to 17 May 2010 are characterized in terms of optical properties and mass concentrations of fine fraction and ash particles. Maximum coarse-mode 500 nm AOTs were of the order of 1.0-1.2. Ash concentrations and column mass loads reached maximum values around 1500 mg/m 3 and 1750 mg/m 2 , respectively, on 16-17 April 2010. In May 2010, the maximum ash loads were lower by at least 50%. A critical aspect of the entire retrieval scheme is the high uncertainty in the mass-to-extinction conversion for fresh volcanic plumes with an unknown concentration of particles with radii >15 mm.Citation: Ansmann, A., et al. (2011), Ash and fine-mode particle mass profiles from EARLINET-AERONET observations over central Europe after the eruptions of the Eyjafjallajökull volcano in 2010,