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Historical stratospheric aerosol optical properties and volcanic sulfur emissions for the next generation of climate models

Thomas J. Aubry1, Matthew Toohey2, Anja Schmidt3,4, Mahesh Kovilakam5,6, Michael Sigl7, Sujan Khanal2, Man Mei Chim8, Ben Johnson9, Simon Carn10, Magali Verkerk1, Zebedee Nicholls11, Isabel Smith1.

  • Affiliations:  1Department of Earth and Environmental Sciences, University of Exeter, Penryn, UK; 2Department of Physics & Engineering Physics, University of Saskatchewan, Canada; 3Institute of Atmospheric Physics (IPA), German Aerospace Center (DLR), Oberpfaffenhofen, Germany; 4Meteorological Institute, Ludwig Maximilian University of Munich, Munich, Germany; 5Adnet Systems, Inc., Bethesda, Maryland, USA; 6NASA Langley Research Center, Hampton, Virginia, USA; 7University of Bern, Climate and Environmental Physics, Physics Institute & Oeschger Centre for Climate Change Research; 8Department of Mathematics, University of Exeter, Exeter, UK; 9UK Met Office, Exeter, UK; 10Department of Geological and Mining Engineering and Sciences, Michigan Technological University, Houghton, USA; 11Climate Resource, Berlin, Germany 

  • Presentation type: Poster

  • Presentation time: Monday 16:30 - 18:30, Room Poster Hall

  • Poster Board Number: 9

  • Programme No: 6.1.15

  • Theme 6 > Session 1

Abstract

Stratospheric aerosols, most of which originate from explosive volcanic sulfur emissions into the stratosphere, are a key natural driver of climate variability. They are thus one of the forcings provided by the Coupled Model Intercomparison Project (CMIP) Climate Forcings Task Team for the CMIP7 Fast Track, a set of climate model experiments designed to deliver the Intergovernmental Panel on Climate Change (IPCC) 7th assessment cycle. In this work, we document the final version of the historical (1750-2023) stratospheric aerosol forcing datasets delivered to modelling groups for CMIP7 Fast Track. We produced one volcanic stratospheric sulfur emission dataset catering for the needs of models which have a prognostic interactive stratospheric aerosol scheme, as well as a stratospheric sulfate aerosol optical property dataset required by models that cannot interactively simulate stratospheric sufate aerosols. For the satellite era (from 1979 onwards), sulfur emissions and sufate aerosol optical properties are based on the MSVOLSO2L4 and GloSSAC datasets, respectively. For the pre-satellite era (1750-1978), the emission dataset is based on ice-core datasets complemented by the geological record for small-moderate magnitude eruptions not captured in ice-core records. Although inferring emissions of these eruptions from the geological record is highly uncertain, our approach minimizes an important bias in the pre-satellite era forcing, both in terms of mean and variability. The pre-satellite aerosol optical property dataset is directly derived from emissions using an updated version of EVA_H, a reduced-complexity volcanic aerosol model. We will discuss the role of the volcanology community in improving these datasets in the future.