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Modeling the Sulfate Aerosol Evolution after Recent Moderate Volcanic Activity, 2008-2012
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  • Christina Brodowsky,
  • Timofei Sukhodolov,
  • Aryeh Feinberg,
  • Michael Höpfner,
  • Thomas Peter,
  • Andrea Stenke,
  • Eugene Rozanov
Christina Brodowsky
Swiss Federal Institute of Technology in Zurich

Corresponding Author:brodowsc@student.ethz.ch

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Timofei Sukhodolov
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Aryeh Feinberg
Swiss Federal Institute of Technology in Zurich
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Michael Höpfner
Karlsruhe Institute of Technology
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Thomas Peter
Swiss Federal Institute of Technology (ETH)
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Andrea Stenke
Institute for Atmospheric and Climate Research
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Eugene Rozanov
Physikalisch-Meteorologisches Observatorium Davos and World Radiation Center
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Volcanic activity is a main natural climate forcing and an accurate representation of volcanic aerosols in global climate models is essential. This is, however, a complex task involving many uncertainties related to the magnitude and vertical distribution of volcanic emissions as well as in observations used for model evaluation. We analyse the performance of the aerosol-chemistry-climate model SOCOL-AERv2 for three medium-sized volcanic eruptions. We investigate the impact of differences in the volcanic plume height and SO2 content on the stratospheric aerosol burden. The influence of internal model variability and dynamics are addressed through an ensemble of free-running and nudged simulations at different vertical resolutions. Comparing the modeled evolution of the stratospheric aerosol loading to satellite measurements reveals a good performance of SOCOL-AERv2. However, the large spread in emission estimates leads to differences in the simulated aerosol burdens resulting from uncertainties in total emitted sulfur and the vertical distribution of injections. The tropopause height varies among the free-running simulations, affecting model results. Conclusive model validation is complicated by uncertainties in observations. In nudged mode, changes in convection and tropospheric clouds affect SO2 oxidation paths and cross-tropopause transport, leading to increased burdens. This effect can be reduced by leaving temperatures unconstrained. A higher vertical resolution of 90 levels increases the stratospheric residence time of sulfate aerosol by reducing the diffusion out of the tropical reservoir. We conclude that the model set-up (vertical resolution, free-running vs. nudged) as well as forcing parameters (volcanic emission strength, plume height) contribute equally to the model uncertainties.
16 Dec 2021Published in Journal of Geophysical Research: Atmospheres volume 126 issue 23. 10.1029/2021JD035472