A. Ackerman, M. Kirkpatrick, D. Stevens, and O. Toon, The impact of humidity above stratiform clouds on indirect aerosol climate forcing, Nature, vol.94, issue.7020, pp.1014-1017, 2004.
DOI : 10.1029/2001JD001011

A. Aiuppa, D. Baker, and J. Webster, Halogens in volcanic systems, Chemical Geology, vol.263, issue.1-4, pp.1-18, 2009.
DOI : 10.1016/j.chemgeo.2008.10.005

B. Albrecht, Aerosols, Cloud Microphysics, and Fractional Cloudiness, Science, vol.245, issue.4923, pp.1227-1230, 1989.
DOI : 10.1126/science.245.4923.1227

A. Ångström, The parameters of atmospheric turbidity, Tellus, pp.64-75, 1964.

J. Baray, Y. Courcoux, P. Keckhut, T. Portafaix, P. Tulet et al., Ma??do observatory: a new high-altitude station facility at Reunion Island (21?? S, 55?? E) for long-term atmospheric remote sensing and in situ measurements, Atmospheric Measurement Techniques, vol.6, issue.10, pp.2865-287710, 2013.
DOI : 10.5194/amt-6-2865-2013

C. Bonadonna, A. Folch, S. Loughlin, and H. Puempel, Future developments in modelling and monitoring of volcanic ash clouds: outcomes from the first IAVCEI-WMO workshop on Ash Dispersal Forecast and Civil Aviation, Bulletin of Volcanology, vol.14, issue.1, pp.1-10, 2012.
DOI : 10.1007/s00445-011-0508-6

F. Bonali, C. Corazzato, and A. Tibaldi, Identifying rift zones on volcanoes: an example from La R??union island, Indian Ocean, Bulletin of Volcanology, vol.7, issue.4, pp.195-204, 2010.
DOI : 10.1007/s00445-010-0416-1

J. Boulon, K. Sellegri, M. Hervo, D. Picard, J. Pichon et al., Investigation of nucleation events vertical extent: a long term study at two different altitude sites, Atmospheric Chemistry and Physics, vol.1151945625, issue.1011, pp.5625-5639, 2011.
URL : https://hal.archives-ouvertes.fr/insu-00649629

C. Brogniez, F. Auriol, C. Deroo, A. Arola, J. Kujanpää et al., Validation of satellite-based noontime UVI with NDACC ground-based instruments: influence of topography, environment and satellite overpass time, Atmospheric Chemistry and Physics, vol.16, issue.23, pp.1-3610, 2016.
DOI : 10.5194/acp-16-15049-2016

D. Muro, A. Métrich, N. Vergani, D. Rose, M. Armienti et al., The Shallow Plumbing System of Piton de la Fournaise Volcano (La Reunion Island, Indian Ocean) Revealed by the Major 2007 Caldera-Forming Eruption, Journal of Petrology, vol.55, issue.7, pp.1287-1315, 2014.
DOI : 10.1093/petrology/egu025

A. Hirsikko, T. Bergman, L. Laakso, M. Dal-maso, I. Riipinen et al., Identification and classification of the Atmos, Chem. Phys. Discuss, vol.5194, p.10, 2016.

P. Hobbs, J. Tuell, D. Hegg, L. Radke, and M. Eltgroth, Particles and gases in the emissions from the 1980???1981 volcanic eruptions of Mt. St. Helens, Journal of Geophysical Research, vol.12, issue.C13, pp.62-11086, 1982.
DOI : 10.1029/JC087iC13p11062

E. Kaminski, S. Tait, F. Ferrucci, M. Martet, B. Hirn et al., Estimation of ash injection in the atmosphere by basaltic volcanic plumes: The case of the Eyjafjallaj??kull 2010 eruption, Journal of Geophysical Research, vol.33, issue.D19, pp.10-1029, 2011.
DOI : 10.1029/2011JB008297

A. Peltier, F. Beauducel, N. Villeneuve, V. Ferrazzini, D. Muro et al., Deep fluid transfer evidenced by surface deformation during the 2014???2015 unrest at Piton de la Fournaise volcano, Journal of Volcanology and Geothermal Research, vol.321, pp.140-148, 2016.
DOI : 10.1016/j.jvolgeores.2016.04.031

J. Penner, M. Andreae, H. Annegarn, L. Barrie, J. Feichter et al., Aerosols, their direct and indirect effects, Climate Change: The scientific basis, pp.289-349

I. Sandu, J. Brenguier, O. Thouron, and B. Stevens, How important is the vertical structure for the representation of aerosol impacts on the diurnal cycle of marine stratocumulus?, Atmospheric Chemistry and Physics, vol.95194, issue.10, pp.4039-4052, 2009.

Y. Seity, P. Brousseau, S. Malardel, G. Hello, P. Bénard et al., The AROME-France Convective-Scale Operational Model, Monthly Weather Review, vol.139, issue.3, pp.976-991, 2011.
DOI : 10.1175/2010MWR3425.1

A. Smirnov, B. N. Holben, T. F. Eck, O. Dubovik, and I. Slutsker, Cloud-Screening and Quality Control Algorithms for the AERONET Database, Remote Sensing of Environment, vol.73, issue.3, pp.337-349, 2000.
DOI : 10.1016/S0034-4257(00)00109-7

T. Staudacher and A. Peltier, Ground deformation at Piton de la Fournaise (La Réunion Island), a review from 20 years of GNSS monitoring

A. Stohl, C. Forster, A. Frank, P. Seibert, and G. Wotawa, Technical note: The Lagrangian particle dispersion model FLEXPART version 6, Atmospheric Chemistry and Physics, vol.25194, issue.510, pp.2461-2474, 2005.
URL : https://hal.archives-ouvertes.fr/hal-00295743

P. Tulet and N. Villeneuve, Large scale modeling of the transport, chemical transformation and mass budget of the sulfur emitted during the eruption of Piton de la Fournaise, Atmospheric Chemistry and Physics, vol.115194, pp.4533-454610, 2007.
URL : https://hal.archives-ouvertes.fr/hal-00961625

L. Réunion, At the top; time series of SO2 concentration (isoline in red) and particle number concentration (isoline in blue) At the bottom; particle number size distribution (colour range) and altitude of the aircraft