Long-range isentropic transport of stratospheric aerosols over 1 Southern Hemisphere following the Calbuco eruption in April 2 2015 3 Nelson. Bègue 1 , Damien. Vignelles 2 , Gwenaël. Berthet 2 , Thierry. Portafaix 1 , Guillaume. 4 Payen 1 , Fabrice. Jégou 2 , Hassan. Benchérif 2,6 , Julien. Jumelet 3 , Jean-Paul Vernier 4 , 5 Thibaut. Lurton 2 , Jean-Baptiste. Renard 2 , Lieven. Clarisse 5 , Vincent. Duverger 2 , 6 Françoise. Posny 1 Jean-Marc. Metzger 1 and Sophie. Godin-Beekmann 3 7 [1] Laboratoire de l’Atmosphère et des Cyclones, UMR 8105 CNRS, Université de la 8 Réunion, Reunion Island, France. 9 [2] Laboratoire de Physique et Chimie de l’Environnement et de l’Espace, Université 10 d’Orléans, CNRS/INSU UMR7328, Orléans, France 11 [3] Laboratoire Atmosphère Milieux Observations Spatiales, University of Paris VI, Paris, 12 France 13 [4] NASA Langley Research Center, Hampton, Virginia, USA 14 [5] Spectroscopie de l’Atmosphère, Service de Chimie Quantique et Photophysique, 15 Université Libre de Bruxelles, Brussels, Belgium 16 [6] School of Chemistry and Physics, University of KwaZulu-Natal, Westville, Durban, South 17 Africa 18 Correspondence to: N.Bègue (nelson.begue@univ-reunion.fr) 19 Abstract 20 After 43 years of inactivity, the Calbuco volcano which is located in the southern part of Chile 21 erupted on 22 April 2015. The space-time evolutions (distribution and transport) of its aerosol 22 plume are investigated by combining satellite (CALIOP, IASI, OMPS), in situ aerosol 23 counting (LOAC OPC) and lidar observations, and the MIMOSA advection model. The 24 Calbuco aerosol plume reached the Indian Ocean 1 week after the eruption. Over the Reunion 25 Island site (21°S; 55.5°E), the aerosol signal was unambiguously enhanced in comparison 26 with “background” conditions with a volcanic aerosol layer extending from 18 km to 21 km 27 during the May-July period. All the data reveal an increase by a factor of ~2 in the SAOD 28 (Stratospheric Aerosol Optical Depth) with respect to values observed before the eruption. 29 Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2017-544 Manuscript under review for journal Atmos. Chem. Phys. Discussion started: 22 June 2017 c  Author(s) 2017. CC BY 4.0 License.