Articles | Volume 16, issue 18
Atmos. Chem. Phys., 16, 11883–11897, 2016
Atmos. Chem. Phys., 16, 11883–11897, 2016

Research article 23 Sep 2016

Research article | 23 Sep 2016

Porous aerosol in degassing plumes of Mt. Etna and Mt. Stromboli

Valery Shcherbakov1,2, Olivier Jourdan1, Christiane Voigt3,4, Jean-Francois Gayet1, Aurélien Chauvigne1, Alfons Schwarzenboeck1, Andreas Minikin3,a, Marcus Klingebiel4,5, Ralf Weigel4, Stephan Borrmann4, Tina Jurkat3, Stefan Kaufmann3, Romy Schlage3, Christophe Gourbeyre1, Guy Febvre1, Tatyana Lapyonok6, Wiebke Frey7,b, Sergej Molleker7, and Bernadett Weinzierl3,8 Valery Shcherbakov et al.
  • 1Laboratoire de Météorologie Physique, UMR 6016 CNRS/Université Clermont Auvergne, Clermont-Ferrand, France
  • 2LaMP, Institut Universitaire de Technologie d'Allier, Montluçon, France
  • 3Institut für Physik der Atmosphäre, Deutsches Zentrum für Luft- und Raumfahrt (DLR), Oberpfaffenhofen, Germany
  • 4Institut für Physik der Atmosphäre, Johannes Gutenberg-Universität Mainz, Mainz, Germany
  • 5Max Planck Institute for Meteorology, Hamburg, Germany
  • 6Laboratoire d'Optique Atmosphérique, UMR 8518 CNRS/Université des Sciences et Technologies de Lille, Villeneuve d'Ascq, France
  • 7Max Planck Institute for Chemistry, Particle Chemistry Department, Mainz, Germany
  • 8University of Vienna, Faculty of Physics, Aerosol Physics and Environmental Physics, Vienna, Austria
  • anow at: Flugexperimente, Deutsches Zentrum für Luft- und Raumfahrt (DLR), Oberpfaffenhofen, Germany
  • bnow at: The University of Manchester, Centre for Atmospheric Science, Manchester, UK

Abstract. Aerosols of the volcanic degassing plumes from Mt. Etna and Mt. Stromboli were probed with in situ instruments on board the Deutsches Zentrum für Luft- und Raumfahrt research aircraft Falcon during the contrail, volcano, and cirrus experiment CONCERT in September 2011. Aerosol properties were analyzed using angular-scattering intensities and particle size distributions measured simultaneously with the Polar Nephelometer and the Forward Scattering Spectrometer probes (FSSP series 100 and 300), respectively. Aerosols of degassing plumes are characterized by low values of the asymmetry parameter (between 0.6 and 0.75); the effective diameter was within the range of 1.5–2.8 µm and the maximal diameter was lower than 20 µm. A principal component analysis applied to the Polar Nephelometer data indicates that scattering features of volcanic aerosols of different crater origins are clearly distinctive from angular-scattering intensities of cirrus and contrails. Retrievals of aerosol properties revealed that the particles were "optically spherical" and the estimated values of the real part of the refractive index are within the interval from 1.35 to 1.38. The interpretation of these results leads to the conclusion that the degassing plume aerosols were porous with air voids. Our estimates suggest that aerosol particles contained about 18 to 35 % of air voids in terms of the total volume.

Final-revised paper