Articles | Volume 17, issue 24
Atmos. Chem. Phys., 17, 15019–15036, 2017
Atmos. Chem. Phys., 17, 15019–15036, 2017

Research article 19 Dec 2017

Research article | 19 Dec 2017

Long-range transport of stratospheric aerosols in the Southern Hemisphere following the 2015 Calbuco eruption

Nelson Bègue1, Damien Vignelles2, Gwenaël Berthet2, Thierry Portafaix1, Guillaume Payen7, Fabrice Jégou2, Hassan Benchérif1,6, Julien Jumelet3, Jean-Paul Vernier4, Thibaut Lurton2,a, Jean-Baptiste Renard2, Lieven Clarisse5, Vincent Duverger2, Françoise Posny1, Jean-Marc Metzger7, and Sophie Godin-Beekmann3 Nelson Bègue et al.
  • 1Laboratoire de l'Atmosphère et des Cyclones, UMR 8105 CNRS, Université de la Réunion, Reunion Island, France
  • 2Laboratoire de Physique et Chimie de l'Environnement et de l'Espace, Université d'Orléans, CNRS UMR7328, Orléans, France
  • 3Laboratoire Atmosphère Milieux Observations Spatiales, University of Paris VI, Paris, France
  • 4NASA Langley Research Center, Hampton, Virginia, USA
  • 5Spectroscopie de l'Atmosphère, Service de Chimie Quantique et Photophysique, Université Libre de Bruxelles, Brussels, Belgium
  • 6School of Chemistry and Physics, University of KwaZulu-Natal, Westville, Durban, South Africa
  • 7Observatoire des Sciences de l'Univers de La Réunion, UMS3365, Saint-Denis de la Réunion, France
  • anow at: Institut Pierre-Simon-Laplace, UPMC/CNRS, 4 place Jussieu, 75252 Paris Cedex 05, France

Abstract. After 43 years of inactivity, the Calbuco volcano, which is located in the southern part of Chile, erupted on 22 April 2015. The space–time evolutions (distribution and transport) of its aerosol plume are investigated by combining satellite (CALIOP, IASI, OMPS), in situ aerosol counting (LOAC OPC) and lidar observations, and the MIMOSA advection model. The Calbuco aerosol plume reached the Indian Ocean 1 week after the eruption. Over the Reunion Island site (21° S, 55.5° E), the aerosol signal was unambiguously enhanced in comparison with background conditions, with a volcanic aerosol layer extending from 18 to 21 km during the May–July period. All the data reveal an increase by a factor of  ∼  2 in the SAOD (stratospheric aerosol optical depth) with respect to values observed before the eruption. The aerosol mass e-folding time is approximately 90 days, which is rather close to the value ( ∼  80 days) reported for the Sarychev eruption. Microphysical measurements obtained before, during, and after the eruption reflecting the impact of the Calbuco eruption on the lower stratospheric aerosol content have been analyzed over the Reunion Island site. During the passage of the plume, the volcanic aerosol was characterized by an effective radius of 0.16 ± 0.02 µm with a unimodal size distribution for particles above 0.2 µm in diameter. Particle concentrations for sizes larger than 1 µm are too low to be properly detected by the LOAC OPC. The aerosol number concentration was  ∼  20 times higher that observed before and 1 year after the eruption. According to OMPS and lidar observations, a tendency toward conditions before the eruption was observed by April 2016. The volcanic aerosol plume is advected eastward in the Southern Hemisphere and its latitudinal extent is clearly bounded by the subtropical barrier and the polar vortex. The transient behavior of the aerosol layers observed above Reunion Island between May and July 2015 reflects an inhomogeneous spatio-temporal distribution of the plume, which is controlled by the localization of these dynamical barriers.

Short summary
The space–time evolutions of the Calbuco plume are investigated by combining satellite, in situ aerosol counting and lidar observations, and a numerical model. All the data at Reunion Island reveal a twofold increase in the amount of aerosol with respect to the values observed before the eruption. The dynamic context has favored the spread of the plume exclusively in the Southern Hemisphere. This study highlights the role played by dynamical barriers in the transport of atmospheric species.
Final-revised paper