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Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/acp-2017-871
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
16 Oct 2017
Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Atmospheric Chemistry and Physics (ACP).
Model simulations of the chemical and aerosol microphysical evolution of the Sarychev Peak 2009 eruption cloud compared to in-situ and satellite observations
Thibaut Lurton1,a, Fabrice Jégou1, Gwenaël Berthet1, Jean-Baptiste Renard1, Lieven Clarisse2, Anja Schmidt3,4, Colette Brogniez5, and Tjarda Roberts1 1LPC2E/CNRS/Université d’Orléans, 3A, avenue de la Recherche Scientifique, F-45071 Orléans Cedex 2, France
2CQP/Université Libre de Bruxelles, CP160/09, avenue F. D. Roosevelt 50, B-1050 Brussels, Belgium
3Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
4Department of Geography, University of Cambridge, Downing Place, Cambridge CB2 3EN, United Kingdom
5Laboratoire d’Optique Atmosphérique, Université Lille 1, Cité Scientifique, F-59655 Villeneuve d’Ascq Cedex, France
anow at: IPSL/CNRS, 4, place Jussieu, F-75252 Paris Cedex 05, France
Abstract. Volcanic eruptions impact climate through the injection of sulfur dioxide (SO2), which is oxidized to form sulfuric acid aerosol particles that can enhance the stratospheric aerosol optical depth (SAOD). Besides large-magnitude eruptions, moderate-magnitude eruptions such as Kasatochi in 2008 and Sarychev Peak in 2009 can have a significant impact on stratospheric aerosol and hence climate. However, uncertainties remain in quantifying the atmospheric and climatic impacts of the 2009 Sarychev Peak eruption due to limitations in previous model representations of volcanic aerosol microphysics and particle size, whilst biases have been identified in satellite estimates of post-eruption SAOD. In addition, the 2009 Sarychev Peak eruption co-injected hydrogen chloride (HCl) alongside SO2, whose potential stratospheric chemistry impacts have not been investigated to date. We present a study of the stratospheric SO2-particle-HCl processing and impacts following Sarychev Peak eruption, using the CESM1(WACCM)-CARMA sectional aerosol microphysics model (with no a priori assumption on particle size). The Sarychev Peak 2009 eruption injected 0.9 Tg of SO2 into the upper troposphere and lower stratosphere (UTLS), enhancing the aerosol load in the Northern hemisphere. The post-eruption evolution of the volcanic SO2 in space and time are well reproduced by the model when compared to IASI (Infrared Atmospheric Sounding Interferometer) satellite data. Co-injection of 27 Gg HCl causes a lengthening of the SO2 lifetime and a slight delay in the formation of aerosols, and acts to enhance the destruction of stratospheric ozone and mono-nitrogen oxides (NOx) compared to the simulation with volcanic SO2 only. We therefore highlight the need to account for volcanic halogen chemistry when simulating the impact of eruptions such as Sarychev on stratospheric chemistry. The model-simulated evolution of effective radius (reff), reflects new particle formation followed by particle growth that enhances reff to reach up to 0.2 µm on zonal average. Comparisons of the model-simulated particle number and size-distributions to balloon-borne in-situ stratospheric observations over Kiruna, Sweden, in August and September 2009, and over Laramie, U.S.A., in June and November 2009 show good agreement and quantitatively confirms the post-eruption particle enhancement. We show that the model-simulated SAOD is consistent with that derived from OSIRIS (Optical Spectrograph and InfraRed Imager System) when both the saturation bias of OSIRIS and the fact that extinction profiles may terminate well above the tropopause are taken into account. Previous modelling studies (involving assumptions on particle size) that reported agreement to (biased) post-eruption estimates of SAOD derived from OSIRIS likely underestimated the climate impact of the 2009 Sarychev Peak eruption.

Citation: Lurton, T., Jégou, F., Berthet, G., Renard, J.-B., Clarisse, L., Schmidt, A., Brogniez, C., and Roberts, T.: Model simulations of the chemical and aerosol microphysical evolution of the Sarychev Peak 2009 eruption cloud compared to in-situ and satellite observations, Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2017-871, in review, 2017.
Thibaut Lurton et al.
Thibaut Lurton et al.
Thibaut Lurton et al.

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Short summary
In 2009 the Sarychev Peak volcano erupted, and impacted the atmospheric chemical composition. This study quantifies the impact of the eruption with numerical models and balloon measurements. Our study considers a wider range of volcanic gases and simulates more precisely the particle size than previous studies. We suggest that previous works around this eruption underestimated its impact, a main reason being that the satellite measurements used to corroborate the models show incomplete data.
In 2009 the Sarychev Peak volcano erupted, and impacted the atmospheric chemical composition....
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