Abstract

AbstractThe radiative forcing caused by a volcanic eruption is dependent on several eruption source parameters such as the mass of sulfur dioxide (SO2) emitted, the eruption column height, and the eruption latitude. General circulation models with prognostic aerosol and chemistry schemes can be used to investigate how each parameter influences the volcanic forcing. However, the range of multidimensional parameter space that can be explored is restricted because such simulations are computationally expensive. Here we use statistical emulation to explore the radiative impact of eruptions over a wide covarying range of SO2 emission magnitudes, injection heights, and eruption latitudes based on only 30 simulations. We use the emulators to build response surfaces to visualize and predict the sulfate aerosol e‐folding decay time, the stratospheric aerosol optical depth, and net radiative forcing of thousands of different eruptions. We find that the volcanic stratospheric aerosol optical depth and net radiative forcing are primarily determined by the mass of SO2 emitted, but eruption latitude is the most important parameter in determining the sulfate aerosol e‐folding decay time. The response surfaces reveal joint effects of the eruption source parameters in influencing the net radiative forcing, such as a stronger influence of injection height for tropical eruptions than high‐latitude eruptions. We also demonstrate how the emulated response surfaces can be used to find all combinations of eruption source parameters that produce a particular volcanic response, often revealing multiple solutions.

Highlights

  • Volcanic eruptions emit SO2 into the atmosphere, which is oxidized and forms sulfate aerosol

  • We find that the volcanic stratospheric aerosol optical depth and net radiative forcing are primarily determined by the mass of SO2 emitted, but eruption latitude is the most important parameter in determining the sulfate aerosol e-folding decay time

  • We have investigated the influence of the mass of SO2 emitted, eruption latitude, and injection height of the emissions on the radiative forcing of a large-magnitude explosive eruption, using a state-of-the-art general circulation model with interactive aerosol microphysics

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Summary

Introduction

Volcanic eruptions emit SO2 into the atmosphere, which is oxidized and forms sulfate aerosol. Several modeling studies have investigated the influence of important eruption source parameters but for only a limited number of eruptions (e.g., Dhomse et al, 2014; English et al, 2013; Jones et al, 2017; Metzner et al, 2014; Niemeier et al, 2009; Timmreck et al, 2010; Toohey et al, 2011, 2013) These studies focus on the effects of variations in individual parameter values, which leaves almost all of the multidimensional parameter space unexplored. This modeling approach creates a major problem for model interpretation if the parameter variations have nonlinear effects or if combinations of parameter perturbations have effects that cannot be predicted from the combined effects of individual parameters

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