Multi-model comparison of the volcanic sulfate deposition from the 1815 eruption of Mt. Tambora

Abstract

Abstract. The eruption of Mt. Tambora in 1815 was the largest volcanic eruption of the past 500 years. The eruption had significant climatic impacts, leading to the 1816 "year without a summer", and remains a valuable event from which to understand the climatic effects of large stratospheric volcanic sulfur dioxide injections. The eruption also resulted in one of the strongest and most easily identifiable volcanic sulfate signals in polar ice cores, which are widely used to reconstruct the timing and atmospheric sulfate loading of past eruptions. As part of the Model Intercomparison Project on the climatic response to Volcanic forcing (VolMIP), five state-of-the-art global aerosol models simulated this eruption. We analyse both simulated background (no Tambora) and volcanic (with Tambora) sulfate deposition to polar regions and compare to ice core records. The models simulate overall similar patterns of background sulfate deposition, alPublished by Copernicus Publications on behalf of the European Geosciences Union. L. Marshall et al.: Multi-model sulfate deposition from the 1815 Tambora eruptionthough there are differences in regional details and magnitude. However, the volcanic sulfate deposition varies considerably between the models with differences in timing, spatial pattern and magnitude. Mean simulated deposited sulfate on Antarctica ranges from 19 to 264 kg km −2 and on Greenland from 31 to 194 kg km −2 , as compared to the mean ice-corederived estimates of roughly 50 kg km −2 for both Greenland and Antarctica. The ratio of the hemispheric atmospheric sulfate aerosol burden after the eruption to the average ice sheet deposited sulfate varies between models by up to a factor of 15. Sources of this inter-model variability include differences in both the formation and the transport of sulfate aerosol. Our results suggest that deriving relationships between sulfate deposited on ice sheets and atmospheric sulfate burdens from model simulations may be associated with greater uncertainties than previously thought.

A New Volcanic Stratospheric Sulfate Aerosol Forcing Emulator (EVA_H): Comparison With Interactive Stratospheric Aerosol Models

“…For the Mount Tambora case (Figure 11, left), the peak SAOD predicted by EVA_H is 20% smaller than the one predicted by EVA, which is largely due to our lower value of the threshold sulfate burden above which Figure 11. Global mean SAOD anomalies following a volcanic SO 2 injection with source parameters similar to those estimated for ( (Marshall et al, 2018;Zanchettin et al, 2016). These models are WACCM (Mills et al, 2016), UM-UKCA (Dhomse et al, 2014), SOCOL (Sheng et al, 2015), and MAECHAM (Niemeier et al, 2009).…”

“…However, there is a large spread among the forcing predicted by these models for a specified volcanic injection (e.g., Zanchettin et al, ). This intermodel uncertainty adds to intramodel uncertainties as well as uncertainties related to constraining eruption source parameters, for example, the mass of SO and eruption latitude reconstructed from ice cores when investigating the impacts of past eruptions (Marshall et al, ; Toohey & Sigl, ). Given the computational cost of interactive stratospheric aerosol models, exploring how the propagation of model and source parameter uncertainties affect the assessment of the climate response to a volcanic eruption is challenging and requires significant efforts such as model intercomparison exercises (e.g., Timmreck et al, ; Zanchettin et al, ).…”

Exploring How Eruption Source Parameters Affect Volcanic Radiative Forcing Using Statistical Emulation

“…However, since the stratospheric dynamics can be modified by aerosol radiative heating and the fact that we have analyzed global and time‐integrated output, the effect of initial conditions is likely second order to that of the eruption source parameters. In simulations of the 1815 Mount Tambora eruption we also found little variation among ensemble members with different initial conditions (Marshall et al, ). Other model outputs such as peak responses or regional impacts, which are likely to have larger extremes, could also be explored using this novel methodology.…”

“…For the model simulations here, aerosol radiative heating is included (Mann et al, ) and the interactive stratospheric aerosol capability has been further improved (Brooke et al, ) to allow sulfuric particles to form heterogeneously on transported meteoric smoke particle cores (MSP). The same model setup has also been applied in preindustrial conditions for the UM‐UKCA 1815 Mount Tambora simulations in Zanchettin et al () and Marshall et al ().…”

Earth System Model Response to Large Midlatitude and High‐latitude Volcanic Eruptions

“…In terms of tenth‐century large eruptions, Eldgjá may be highlighted rather than Paektusan because of the large amount of ice core sulfur from Eldgjá that would lead to a strong negative radiative forcing (Sigl et al, ). However, the magnitude of the 946–947 Paektusan eruption is estimated at 6.8–7.4 (Hayakawa & Koyama, ; Xu et al, ), which is of similar magnitude to the infamous 1815 Tambora eruption (7.0; Xu et al, ) that caused the “year without a summer.” The latest estimates for the 1815 Tambora SO 2 emission are 60 Mt (Marshall et al, ; Zanchettin et al, ) with uncertainty of 30 to 80 Mt (e.g., Stoffel et al, ). Compare this to 1991 Pinatubo estimated at 10 Mt (Mills et al, ) or 20 Mt (Bluth et al, ), 1883 Krakatau at 30 Mt (Stothers, ), but recently both at about the same emissions (Sigl et al, ).…”