EGU2020-5254, updated on 24 Apr 2024
https://doi.org/10.5194/egusphere-egu2020-5254
EGU General Assembly 2020
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.

Large variations in volcanic aerosol forcing efficiency due to eruption source parameters and rapid adjustments

Lauren Marshall1, Christopher Smith2, Piers Forster2, Thomas Aubry3, and Anja Schmidt3
Lauren Marshall et al.
  • 1Department of Chemistry, University of Cambridge, Cambridge, UK (lrm49@cam.ac.uk)
  • 2Priestely International Centre for Climate, University of Leeds, Leeds, UK
  • 3Department of Geography, University of Cambridge, Cambridge, UK

The relationship between volcanic stratospheric aerosol optical depth (SAOD) and volcanic forcing is key to quantify the climate impacts of volcanic eruptions. In their fifth assessment report, the Intergovernmental Panel on Climate Change uses a single scaling factor between volcanic SAOD and effective radiative forcing (ERF) based on climate model simulations of the 1991 Mt. Pinatubo eruption, which may not be appropriate for eruptions of different magnitudes. Using a large-ensemble of aerosol-chemistry-climate simulations of eruptions with different SO2 emissions, latitudes, emission altitudes and seasons, we find that the effective radiative forcing is on average 21% less than the instantaneous radiative forcing, predominantly due to a positive shortwave cloud adjustment.  In our model, the volcanic SAOD to ERF relationship is non-unique and depends strongly on eruption latitude and season. We recommend a power law fit in the form of ERF = -15.1 × SAOD0.88 to convert SAOD (in the range of 0.01-0.7) to ERF.

How to cite: Marshall, L., Smith, C., Forster, P., Aubry, T., and Schmidt, A.: Large variations in volcanic aerosol forcing efficiency due to eruption source parameters and rapid adjustments, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5254, https://doi.org/10.5194/egusphere-egu2020-5254, 2020.

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