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The Role of the SO 2 Radiative Effect in Sustaining the Volcanic Winter and Soothing the Toba Impact on Climate
Author(s) -
Osipov Sergey,
Stenchikov Georgiy,
Tsigaridis Kostas,
LeGrande Allegra N.,
Bauer Susanne E.
Publication year - 2020
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1029/2019jd031726
Subject(s) - volcano , radiative forcing , atmospheric sciences , plume , radiative transfer , sulfate aerosol , longwave , environmental science , climate model , climatology , panache , sulfate , aerosol , climate change , geology , meteorology , chemistry , stratosphere , geography , physics , seismology , oceanography , organic chemistry , quantum mechanics
Volcanic eruptions are an important climate driver. The impact of Pinatubo‐sized eruptions has been observed and is well constrained. The magnitude and duration of volcanic winter effects after supereruptions such as Toba remain disputed due to disagreement between the strong cooling predicted by models and much milder climate perturbations according to the paleodata. Here we present a reevaluated climate impact of a Toba‐sized supereruption based on up‐to‐date GISS ModelE simulations. In this study, we account for all known primary mechanisms that govern the evolution of the volcanic plume and their nonlinear interactions. The SO2radiative effects are evaluated for the first time in coupled climate simulations with the interactive atmospheric chemistry module. We found that SO2effects on photochemistry, dynamics, and radiative forcing are especially prominent. Due to strong absorption in ultraviolet, SO2feedback on photochemistry partially offsets the limiting effect associated with aerosol microphysical processes. SO2greenhouse warming soothes the radiative cooling exerted by sulfate aerosols. SO2absorption in the shortwave and longwave causes radiative heating and lofting of the volcanic plume, and boosts the efficiency of SO2impact on photochemistry. Our analysis shows that SO2lifetime and magnitude of effects scale up and increase with the amount of emitted material. For a Pinatubo‐sized eruption, SO2feedbacks on chemistry and dynamics are relevant only during the initial stage of the volcanic plume evolution, while local SO2concentrations are high. For a Toba‐sized eruption, SO2effects are as important as sulfate aerosols and produce a less extreme volcanic winter.