ACP Atmospheric Chemistry and Physics ACP Atmos. Chem. Phys. 1680-7324 Copernicus Publications Göttingen, Germany 10.5194/acp-13-6533-2013 Stratospheric aerosols from the Sarychev volcano eruption in the 2009 Arctic summer Jégou F. https://orcid.org/0000-0003-3527-1399 1 Berthet G. https://orcid.org/0000-0003-3169-1636 1 Brogniez C. 2 Renard J.-B. 1 François P. 2 Haywood J. M. 5 3 4 Jones A. https://orcid.org/0000-0003-1814-7601 4 Bourgeois Q. 6 Lurton T. 1 Auriol F. 2 Godin-Beekmann S. 7 Guimbaud C. 1 Krysztofiak G. 1 Gaubicher B. 1 Chartier M. 1 Clarisse L. https://orcid.org/0000-0002-8805-2141 8 Clerbaux C. 7 Balois J. Y. 2 Verwaerde C. 2 Daugeron D. 1 Laboratoire de Physique et Chimie de l'Environnement et de l'Espace, Université d'Orléans, CNRS/INSU UMR7328, Orléans, France Laboratoire d'Optique Atmosphérique, Université Lille 1 Sciences et Technologies, CNRS/INSU UMR8518, Villeneuve d'Ascq, France Observational Based Research, Met Office, Exeter, UK Earth System and Mitigation Science, Met Office Hadley Centre, Exeter, UK College of Engineering, Mathematics, and Physical Sciences, University of Exeter, Exeter, UK Center for Climate Systems Modeling, Institute for Atmospheric and Climate Science, ETH Zürich, Zürich, Switzerland Laboratoire Atmosphères Milieux Observations Spatiales, UPMC, Université Paris 06, Université Versailles Saint Quentin, CNRS/INSU UMR8190, LATMOS-IPSL, Paris, France Spectroscopie de l'Atmosphère, Service de Chimie Quantique et Photophysique, Université Libre de Bruxelles, Brussels, Belgium 10 07 2013 13 13 6533 6552 Copyright: © 2013 F. Jégou et al. 2013 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://acp.copernicus.org/articles/13/6533/2013/acp-13-6533-2013.html The full text article is available as a PDF file from https://acp.copernicus.org/articles/13/6533/2013/acp-13-6533-2013.pdf

Aerosols from the Sarychev volcano eruption (Kuril Islands, northeast of Japan) were observed in the Arctic lower stratosphere a few days after the strongest SO<sub>2</sub> injection which occurred on 15 and 16 June 2009. From the observations provided by the Infrared Atmospheric Sounding Interferometer (IASI) an estimated 0.9 Tg of sulphur dioxide was injected into the upper troposphere and lower stratosphere (UTLS). The resultant stratospheric sulphate aerosols were detected from satellites by the Optical Spectrograph and Infrared Imaging System (OSIRIS) limb sounder and by the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) and from the surface by the Network for the Detection of Atmospheric Composition Changes (NDACC) lidar deployed at OHP (Observatoire de Haute-Provence, France). By the first week of July the aerosol plume had spread out over the entire Arctic region. The Sarychev-induced stratospheric aerosol over the Kiruna region (north of Sweden) was measured by the Stratospheric and Tropospheric Aerosol Counter (STAC) during eight balloon flights planned in August and September 2009. During this balloon campaign the Micro Radiomètre Ballon (MicroRADIBAL) and the Spectroscopie d'Absorption Lunaire pour l'Observation des Minoritaires Ozone et NOx (SALOMON) remote-sensing instruments also observed these aerosols. Aerosol concentrations returned to near-background levels by spring 2010. The effective radius, the surface area density (SAD), the aerosol extinction, and the total sulphur mass from STAC in situ measurements are enhanced with mean values in the range 0.15–0.21 μm, 5.5–14.7 μm<sup>2</sup> cm<sup>−3</sup>, 5.5–29.5 × 10<sup>−4</sup> km<sup>−1</sup>, and 4.9–12.6 × 10<sup>−10</sup> kg[S] kg<sup>−1</sup>[air], respectively, between 14 km and 18 km. The observed and modelled e-folding time of sulphate aerosols from the Sarychev eruption is around 70–80 days, a value much shorter than the 12–14 months calculated for aerosols from the 1991 eruption of Mt Pinatubo. The OSIRIS stratospheric aerosol optical depth (AOD) at 750 nm is enhanced by a factor of 6, with a value of 0.02 in late July compared to 0.0035 before the eruption. The HadGEM2 and MIMOSA model outputs indicate that aerosol layers in polar region up to 14–15 km are largely modulated by stratosphere–troposphere exchange processes. The spatial extent of the Sarychev plume is well represented in the HadGEM2 model with lower altitudes of the plume being controlled by upper tropospheric troughs which displace the plume downward and upper altitudes around 18–20 km, in agreement with lidar observations. Good consistency is found between the HadGEM2 sulphur mass density and the value inferred from the STAC observations, with a maximum located about 1 km above the tropopause ranging from 1 to 2 × 10<sup>−9</sup> kg[S] kg<sup>−1</sup>[air], which is one order of magnitude higher than the background level.

 References Baran, A. J. and Foot, J. S.: A new application of the operational sounder HIRS in determining a climatology of sulphuric acid aerosol from the Pinatubo eruption, J. Geophys. Res., 99, 25673–25679, <a href="http://dx.doi.org/10.1029/94JD02044">https://doi.org/10.1029/94JD02044</a>, 1994. Barkley, M. P., Palmer, P. I., Boone, C. D., Bernath, P. F., and Suntharalingam, P.: Global distributions of carbonyl sulfide in the upper troposphere and stratosphere, Geophys. Res. Lett., 35, L14810, <a href="http://dx.doi.org/10.1029/2008GL034270">https://doi.org/10.1029/2008GL034270</a>, 2008. Bauman, J. J.,Russell, P. B., Geller, M. A., and Hamill, P.: A stratospheric aerosol climatology from SAGE II and CLAES measurements: 2. Results and comparisons, 1984–1999, J. Geophys. Res., 108, 4383, <a href="http://dx.doi.org/10.1029/2002JD002993">https://doi.org/10.1029/2002JD002993</a>, 2003. Bellouin, N., Boucher, O., Haywood, J. M., Johnson, C., Jones, A., Rae, J., and Woodward, S.: Improved representation of aerosols for HadGEM2, Tech. Note 73, Met Office Hadley Centre, Exeter, UK, 2007. Berthet, G, Renard, J.-B., Brogniez, C., Robert, C., Chartier, M., and Pirre, M.: Optical and physical properties of stratospheric aerosols from balloon measurements in the visible and near-infrared domains. I. Analysis of aerosol extinction spectra from the AMON and SALOMON balloonborne spectrometers,, Appl. Optics, 41 7522–7539, 2002. Berthet, G, Renard, J.-B., Catoire, V., Chartier, M., Robert, C., Huret, N., Coquelet, F., Bourgeois, Q., Rivière, E. D., Barret, B., Lefèvre, F., and Hauchecorne, A.: Remote sensing measurements in the polar vortex: comparison to in situ observations and implications for the simultaneous retrievals and analysis of the NO<sub>2</sub> and OClO species, J. Geophys. Res., 112, D21310, <a href="http://dx.doi.org/10.1029/2007JD008699">https://doi.org/10.1029/2007JD008699</a>, 2007. Bluth, G. J. S., Doiron, S. D., Schnetzler, C. C., Krueger, A. J., and Walter, L. S.: Global tracking of the SO<sub>2</sub> clouds from the June 1991 Mount Pinatubo eruptions, Geophys. Res. Lett., 19, 151–154, <a href="http://dx.doi.org/10.1029/91GL02792">https://doi.org/10.1029/91GL02792</a>, 1992. Bluth, G. J. S., Rose, W. I., Sprod, I. E., and Krueger, A. J.: Stratospheric loading from explosive volcanic eruptions, J. Geol., 105, 671–684, <a href="http://dx.doi.org/10.1086/515972">https://doi.org/10.1086/515972</a>, 1997. Bourassa, A. E., Degenstein, D. A., Elash, B. J., and Llewellyn, E. J.: Evolution of the stratospheric aerosol enhancement following the eruptions of Okmok and Kasatochi: Odin–OSIRIS measurements, J. Geophys. Res., 115, D00L03, <a href="http://dx.doi.org/10.1029/2009JD013274">https://doi.org/10.1029/2009JD013274</a>, 2010. Bourassa, A., Robock, A., Randel, W., Deshler, T., Rieger, L., Lloyd, N., Llewellyn, E. J., and Degenstein, D.: Large Volcanic Aerosol Load in the Stratosphere Linked to Asian Monsoon Transport, Science, 337, 78–81, 2012a. Bourassa, A. E., Rieger, L. A., Lloyd, N. D., and Degenstein, D. A.: Odin-OSIRIS stratospheric aerosol data product and SAGE III intercomparison, Atmos. Chem. Phys., 12, 605–614, <a href="http://dx.doi.org/10.5194/acp-12-605-2012">https://doi.org/10.5194/acp-12-605-2012</a>, 2012b. Bourassa, A. E., McLinden, C. A., Bathgate, A. F., Elash, B. J., and Degenstein, D. A.: Precision estimate for Odin-OSIRIS limb scatter retrievals, J. Geophys. Res., 117, D04303, <a href="http://dx.doi.org/10.1029/2011JD016976">https://doi.org/10.1029/2011JD016976</a>, 2012c. Brogniez, C., Huret, N., Eckermann, S., Rivière, E. D., Pirre, M., Herman, M., Balois, J.-Y., Verwaerde, C., Larsen, N., and Knudsen, B.: Polar stratospheric cloud microphysical properties measured by the microRADIBAL instrument on 25 January 2000 above Esrange and modeling interpretation, J. Geophys. Res., 108, 8332, <a href="http://dx.doi.org/10.1029/2001JD001017">https://doi.org/10.1029/2001JD001017</a>, 2003. Brühl, C., Lelieveld, J., Crutzen, P. J., and Tost, H.: The role of carbonyl sulphide as a source of stratospheric sulphate aerosol and its impact on climate, Atmos. Chem. Phys., 12, 1239–1253, <a href="http://dx.doi.org/10.5194/acp-12-1239-2012">https://doi.org/10.5194/acp-12-1239-2012</a>, 2012. Carslaw, K. C. and Kärcher, B.: Stratospheric aerosol processes, in Assessment of Stratospheric Aerosol Properties, edited by L. Thomason and T. Peter, WCRP 124, WMO/TD 1295, SPARC Rep. 4, World Meteorol. Organ., Geneva, Switzerland, 2006. Clarisse, L., Coheur, P. F., Prata, A. J., Hurtmans, D., Razavi, A., Phulpin, T., Hadji-Lazaro, J., and Clerbaux, C.: Tracking and quantifying volcanic SO<sub>2</sub> with IASI, the September 2007 eruption at Jebel at Tair, Atmos. Chem. Phys., 8, 7723–7734, <a href="http://dx.doi.org/10.5194/acp-8-7723-2008">https://doi.org/10.5194/acp-8-7723-2008</a>, 2008. Clarisse, L., Hurtmans, D., Clerbaux, C., Hadji-Lazaro, J., Ngadi, Y., and Coheur, P.-F.: Retrieval of sulphur dioxide from the infrared atmospheric sounding interferometer (IASI), Atmos. Meas. Tech., 5, 581–594, <a href="http://dx.doi.org/10.5194/amt-5-581-2012">https://doi.org/10.5194/amt-5-581-2012</a>, 2012. Clerbaux, C., Boynard, A., Clarisse, L., George, M., Hadji-Lazaro, J., Herbin, H., Hurtmans, D., Pommier, M., Razavi, A., Turquety, S., Wespes, C., and Coheur, P.-F.: Monitoring of atmospheric composition using the thermal infrared IASI/MetOp sounder, Atmos. Chem. Phys., 9, 6041–6054, <a href="http://dx.doi.org/10.5194/acp-9-6041-2009">https://doi.org/10.5194/acp-9-6041-2009</a>, 2009. Collins, W. J., Bellouin, N., Doutriaux-Boucher, M., Gedney, N., Hinton, T., Jones, C. D., Liddicoat, S., Martin, G., O'Connor, F., Rae, J., Senior, C., Totterdell, I., Woodward, S., Reichler T., and Kim J.: Evaluation of the HadGEM2 model, Tech. Note 74, Met Office Hadley Centre, Exeter, UK, 2008. d'Amico, G., Amodeo, A., Boselli, A., Giunta, A., Madonna, F., Mona, L., Pappalardo, G., Haywood, J., Jones, A., Bellouin, N., and Telford, P.: Stratospheric aerosol layers over southern Italy during the summer of 2009: Lidar observations and model comparison, paper presented at 25th International Laser Radar Conference, Int. Radiat. Comm., Int. Assoc. of Meteorol. and Atmos. Phys., St. Petersburg, Russia, 2010. Deshler, T., Hervig, M. E., Hofmann, D. J., Rosen, J. M., and Liley, J. B.: Thirty years of in situ stratospheric aerosol size distribution measurements from Laramie, Wyoming (41° N), using balloon-borne instruments, J. Geophys. Res., 108, 4167, <a href="http://dx.doi.org/10.1029/2002JD002514">https://doi.org/10.1029/2002JD002514</a>, 2003. Doeringer, D., Eldering, A., Boone, C. D., González Abad, G., and Bernath, P. F.: Observation of sulfate aerosols and SO<sub>2</sub> from the Sarychev volcanic eruption using data from the Atmospheric Chemistry Experiment (ACE), J. Geophys. Res., 117, D03203, <a href="http://dx.doi.org/10.1029/2011JD016556">https://doi.org/10.1029/2011JD016556</a>, 2012. Godin-Beekmann, S., Porteneuve, J., and Garnier, A.: Systematic DIAL lidar monitoring of the stratospheric ozone vertical distribution at Observatoire de Haute-Provence (43.92° N, 5.71° E), J. Environ. Monit., 5, 57–67, 2003. Hamill, P., Jensen, E. J., Russell, P. B., and Bauman, J. J.: The life cycle of stratospheric aerosol particles, B. Am. Meteorol. Soc., 78, 1395–1410, <a href="http://dx.doi.org/10.1175/1520-0477(1997)078<1395:TLCOSA>2.0.CO;2">https://doi.org/10.1175/1520-0477(1997)078<1395:TLCOSA>2.0.CO;2</a>, 1997. Hauchecorne, A., Godin, S., Marchand, M., Heese, B., and Souprayen, C.: Quantification of the transport of chemical constituents from the polar vortex to midlatitudes in the lower stratosphere using the high-resolution advection model MIMOSA and effective diffusivity, J. Geophys. Res., 107, 8289, <a href="http://dx.doi.org/10.1029/2001JD000491">https://doi.org/10.1029/2001JD000491</a>, 2002. Haywood, J. M., Jones, A., Clarisse, L., Bourassa, A., Barnes, J., Telford, P., Bellouin, N., Boucher, O., Agnew, P., Clerbaux, C., Coheur, P., Degenstein, D., and Braesicke, P.: Observations of the eruption of the Sarychev volcano and simulations using the HadGEM2 climate model, J. Geophys. Res., 115, D21212, <a href="http://dx.doi.org/10.1029/2010JD014447">https://doi.org/10.1029/2010JD014447</a>, 2010. Hofmann, D., Barnes, J., O'Neill, M., Trudeau, M., and Neely, R.: Increase in background stratospheric aerosol observed with lidar at Mauna Loa Observatory and Boulder, Colorado, Geophys. Res. Lett., 36, L15808, <a href="http://dx.doi.org/10.1029/2009GL039008">https://doi.org/10.1029/2009GL039008</a>, 2009. Holton, J. R., Haynes, P. H., McIntyre, M. E., Douglass, A. R., Rood, R. B., and Pfister, L.: stratosphere-troposphere exchange, Rev. Geophys., 33, 403–439, <a href="http://dx.doi.org/10.1029/95RG02097">https://doi.org/10.1029/95RG02097</a>, 1995. Holton, J.: An Introduction to Dynamic Meteorology, 4th ed., 535 pp., Elsevier, Burlington, Mass, 2004. Jones, A., Roberts, D. L., Woodage, M. J., and Johnson, C. E.: Indirect sulphate aerosol forcing in a climate model with an interactive sulphur cycle, J. Geophys. Res., 106, 20293–20310, <a href="http://dx.doi.org/10.1029/2000JD000089">https://doi.org/10.1029/2000JD000089</a>, 2001. Jones, A., Haywood, J., Boucher, O., Kravitz, B., and Robock, A.: Geoengineering by stratospheric SO<sub>2</sub> injection: results from the Met Office HadGEM2 climate model and comparison with the Goddard Institute for Space Studies ModelE, Atmos. Chem. Phys., 10, 5999–6006, <a href="http://dx.doi.org/10.5194/acp-10-5999-2010">https://doi.org/10.5194/acp-10-5999-2010</a>, 2010. Klett, J. D.: Stable analytical inversion solution for processing lidar returns, Appl. Opt., 20, 211–220, <a href="http://dx.doi.org/10.1364/AO.20.000211">https://doi.org/10.1364/AO.20.000211</a>, 1981. Kravitz, B., Robock, A., and Bourassa, A.: Negligible climatic effects from the 2008 Okmok and Kasatochi volcanic eruptions, J. Geophys. Res., 115, D00L05, <a href="http://dx.doi.org/10.1029/2009JD013525">https://doi.org/10.1029/2009JD013525</a>, 2010. Kravitz, B., Robock, A., Bourassa, A., Deshler, T., Wu, D., Mattis, I., Finger, F., Hoffmann, A., Ritter, C., Bitar, L., Duck, T. J., and Barnes, J. E.: Simulation and observations of stratospheric aerosols from the 2009 Sarychev volcanic eruption, J. Geophys. Res., 116, D18211, <a href="http://dx.doi.org/10.1029/2010JD015501">https://doi.org/10.1029/2010JD015501</a>, 2011. Kristiansen, N. I., Stohl, A., Prata, A. J., Richter, A., Eckhardt, S., Seibert, P., Hoffmann, A., Ritter, C., Bitar, L., Duck, T. J., and Stebelet, K.: Remote sensing and inverse transport modeling of the Kasatochi eruption sulfur dioxide cloud, J. Geophys. Res., 115, D00L16, <a href="http://dx.doi.org/10.1029/2009JD013286">https://doi.org/10.1029/2009JD013286</a>, 2010. Krotkov, N. A., Schoeberl, M. R., Morris, G. A., Carn, S., and Yang, K.: Dispersion and lifetime of the SO<sub>2</sub> cloud from the August 2008 Kasatochi eruption, J. Geophys. Res., 115, D00L20, <a href="http://dx.doi.org/10.1029/2010JD013984">https://doi.org/10.1029/2010JD013984</a>, 2010. Liu, Z., Vaughan, M., Winker, D., Kittaka, C., Getzewich, B., Kuehn, R., Omar, A., Powell, K., Trepte, C., and Hostetler, C.: The CALIPSO lidar cloud and aerosol discrimination: Version 2 algorithm and initial assessment of performance, J. Atmos. Oceanic Technol., 26, 1198–1213, 2009. Llewellyn, E. J., Lloyd, N. D., Degenstein, D. A., Gattinger, R. L., Petelina, S. V., Bourassa, A. E., Wiensz, J. T., Ivanov, E. V., McDade, I. C., Solheim, B. H., McConnell, J. C., Haley, C. S., von Savigny, C., Sioris, C. E., McLinden, C. A., Griffioen, E., Kaminski, J., Evans, W. F. J., Puckrin, E., Strong, K., Wehrle, V., Hum, R. H., Kendall, D. J. W., Matsushita, J., Murtagh, D. P., Brohede, S., Stegman, J., Witt, G., Barnes, G., Payne, W. F., Piché, L., Smith, K., Warshaw, G., Deslauniers, D. L., Marchand, P., Richardson, E. H., King, R. A., Wevers, I., McCreath, W., Kyrölä, E., Oikarinen, L., Leppelmeier, G. W., Auvinen, H., Mégie, G., Hauchecorne, A., Lefèvre, F, de La Noë, J., Ricaud, P., Frisk, U., Sjoberg, F., von Schéele, F., and Nordh, L.: The OSIRIS instrument on the Odin spacecraft, Can. J. Phys., 82, 411–422, <a href="http://dx.doi.org/10.1139/P04-005">https://doi.org/10.1139/P04-005</a>, 2004. Mattis, I., Siefert, P., Müller, D., Tesche, M., Hiebsch, A., Kanitz, T., Schmidt, J., Finger, F. Wandinger, U., and Ansmann, A.: Volcanic aerosol layers observed with multiwavelength Raman lidar over central Europe in 2008–2009, J. Geophys. Res., 115, D00L04, <a href="http://dx.doi.org/10.1029/2009JD013472">https://doi.org/10.1029/2009JD013472</a>, 2010. Notholt J. and Bingemer, H.: Precursor Gas Measurements, in: Assessment of Stratospheric Aerosol Properties, edited by: Thomason, L. and Peter, T., WCRP 124, WMO/TD 1295, SPARC Rep. 4, World Meteorol. Organ., Geneva, Switzerland, 2006. Oman, L., Robock, A., Stenchikov, G. L., Schmidt, G. A., and Ruedy, R.: Climatic response to high-latitude volcanic eruptions, J. Geophys. Res., 110, D13103, <a href="http://dx.doi.org/10.1029/2004JD005487">https://doi.org/10.1029/2004JD005487</a>, 2005. O'Neill, N. T., Perro, C., Saha, A., Lesins, G., Duck, T. J., Eloranta, E. W., Nott, G. J., Hoffman, A., Karumudi, M. L., Ritter, C., Bourassa, A., Abboud, I., Carn, S. A., and Savastiouk, V.: Properties of Sarychev sulphate aerosols over the Arctic, J. Geophys. Res., 117, D04203, <a href="http://dx.doi.org/10.1029/2011JD016838">https://doi.org/10.1029/2011JD016838</a>, 2012. Pommereau, J.-P. and Piquard, J.: Ozone and nitrogen dioxide vertical distributions by UV-visible solar occultation from balloons, Geophys. Res. Lett., 21, 1227–1230, 1994. Renard, J.-B., Chartier, M., Robert, C., Chalumeau, G., Berthet, G., Pirre, M., Pommereau, J. P., and Goutail, F.: SALOMON: a new, light balloon borne UV-visible spectrometer for nighttime observations of stratospheric trace-gas species, Appl. Optics, 39, 386–392, 2000. Renard, J.-B., Berthet, G., Robert, C., Chartier, M., Pirre, M., Brogniez, C., Herman, M., Verwaerde, C., Balois, J.-Y., Ovarlez, J., Ovarlez, H., Crespin, J., and Deshler, T.: Optical and physical properties of stratospheric aerosols from balloon measurements in the visible and near-infrared domain: 2. Comparison of extinction, reflectance, polarization and counting measurements, Appl. Opt., 41, 7540–7549, 2002. Renard, J.-B., Berthet, G., Robert, C., Chartier, M., Pirre, M., Brogniez, C., Herman, M., Verwaerde, C., Balois, J.-Y., Ovarlez, H., Crespin, J., and Deshler, T.: Optical and physical properties of stratospheric aerosols from balloon measurements in the visible and near–infrared domains. III. Presence of aerosols in the middle stratosphere, Appl. Opt., 44, 4086–4095, <a href="http://dx.doi.org/10.1364/AO.44.004086">https://doi.org/10.1364/AO.44.004086</a>, 2005. Renard, J.-B., Brogniez, C., Berthet, G., Bourgeois, Q., Gaubichet, B., Chartier, M., Balois, J.-Y., Verwaerde, C., Auriol, F., Fran\c cois, P., Daugeron, D., and Engrand, C.: Vertical distribution of the different types of aerosols in the stratosphere, Detection of solid particles and analysis of their spatial variability, J. Geophys. Res., 113, D21303, <a href="http://dx.doi.org/10.1029/2008JD010150">https://doi.org/10.1029/2008JD010150</a>, 2008. Renard, J.-B., Berthet, G, Salazar, S., Catoire, V., Tagger, T., Gaubicher, B., and Robert, C: In situ detection of aerosol layers in the middle stratosphere, Geophys. Res. Lett., 37, L20803, <a href="http://dx.doi.org/10.1029/2010GL044307">https://doi.org/10.1029/2010GL044307</a>, 2010. Robock, A.: Volcanic eruptions and climate, Rev. Geophys., 38, 191–219, <a href="http://dx.doi.org/10.1029/1998RG000054">https://doi.org/10.1029/1998RG000054</a>, 2000. Rybin, A, Chibisova, M., Webley, P., Steensen, T., Izbekov, P., Neal, C., and Realmuto, V.: Satellite and ground observations of the June 2009 eruption of Sarychev Peak volcano, Matua Island, Central Kuriles, Bull. Volcanol., 73, 1377–1392, <a href="http://dx.doi.org/10.1007/s00445-011-0481-0">https://doi.org/10.1007/s00445-011-0481-0</a>, 2011. Sawamura, P., Vernier, J. P., Barnes, J. E., Berkoff, T. A., Welton, E. J., Alados-Arboledas, L., Navas-Guzm'an, F., Pappalardo, G., Mona, L., Madonna, F., Lange, D., Sicard, M., Godin-Beekmann, S., Payen, G., Wang, Z., Hu, S., Tripathi, S. N., Cordoba-Jabonero, C., and Hoff, R. M.: Stratospheric AOD after the 2011 eruption of Nabro volcano measured by lidars over the Northern Hemisphere, Environ. Res. Lett., 7, 034013, <a href="http://dx.doi.org/10.1088/1748-9326/7/3/034013">https://doi.org/10.1088/1748-9326/7/3/034013</a>, 2012. Solomon, S., Daniel, J. S., Neely III, R. R., Vernier, J.-P., Dutton, E. G., and Thomason, L. W.: The persistently variable "Background" stratospheric aerosol layer and global climate change, Science 333, 866, <a href="http://dx.doi.org/10.1126/science.1206027">https://doi.org/10.1126/science.1206027</a>, 2011. Van de Hulst, H. C.: Light Scattering By Small Particles, John Wiley & Sons, Inc., New York, 1957. Vernier, J.-P., Thomason, L. W., Pommereau, J.-P., Bourassa, A., Pelon, J., Garnier, A., Hauchecorne, A., Blanot, L., Trepte, C., Degenstein, D., and Vargas, F.: Major influence of tropical volcanic eruptions on the stratospheric aerosol layer during the last decade, Geophys. Res. Lett., 38, L12807, <a href="http://dx.doi.org/10.1029/2011GL047563">https://doi.org/10.1029/2011GL047563</a>, 2011. Weisenstein, D. and Bekki, S.: Modeling of Stratospheric Aerosol, in: Assessment of Stratospheric Aerosol Properties, edited by: Thomason, L. and Peter, T., WCRP 124, WMO/TD 1295, SPARC Rep. 4, World Meteorol. Organ., Geneva, Switzerland, 2006. Willeke, K. and Liu, B. Y. H.: Single particle optical counter: principle and application, in Fine Particles, Aerosol Generation, Measurement, Sampling and Analysis, B. Y. H. Liu, ed. Academic, Orlando, Fla., 698–729, 1976. Winker, D. M., Hunt, W. H., and McGill, M. J.: Initial performance assessment of CALIOP, Geophys. Res. Lett., 34, L19803, <a href="http://dx.doi.org/10.1029/2007GL030135">https://doi.org/10.1029/2007GL030135</a>, 2007. Winker, D. M., Vaughan, M. A., Omar, A., Hu, Y., Powell, K. A., Liu, Z., Hunt, W. H., and Young, S. A.: Overview of the CALIPSO mission and CALIOP data processing algorithms, J. Atmos. Oceanic Technol., 26, 2310–2323, 2009.