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

Valery Shcherbakov (1, 2) , Olivier Jourdan (3) , Christiane Voigt (4) , Jean-François Gayet (3) , Aurélien Chauvigné (2) , Alfons Schwarzenboeck (3) , Andreas Minikin (4) , Marcus Klingebiel , Ralf Weigel (5) , Stephan Borrmann (6) , Tina Jurkat , Stefan Kaufmann (7) , Romy Schlage , Christophe Gourbeyre (3) , Guy Febvre (3) , Tatyana Lapyonok , Wiebke Frey , Sergej Molleker , Bernadett Weinzierl (4)

1 IUT d'Allier - IUT d'Allier
2 LaMP - Laboratoire de Météorologie Physique
3 LaMP - Laboratoire de météorologie physique
4 IPA - DLR Institut für Physik der Atmosphäre = DLR Institute of Atmospheric Physics
5 IPA - Institut für Physik der Atmosphäre [Mainz]
6 MPIC - Max-Planck-Institut für Chemie
7 Universität Heidelberg [Heidelberg] = Heidelberg University

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 Neph-elometer 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.

Domaines: Physique Atmosphérique et Océanique [physics.ao-ph]; Océan, Atmosphère

Valery Shcherbakov, Olivier Jourdan, Christiane Voigt, Jean-François Gayet, Aurélien Chauvigné, et al.. Porous aerosol in degassing plumes of Mt. Etna and Mt. Stromboli. Atmospheric Chemistry and Physics, 2016, 16 (18), pp.11883 - 11897. ⟨10.5194/acp-16-11883-2016⟩. ⟨hal-01823396⟩