the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 22 Feb 2023
A regional modelling study of halogen chemistry within a volcanic plume of Mt Etna’s Christmas 2018 eruption
Abstract. Volcanoes are known to be important emitters of atmospheric gases and aerosols, which for certain volcanoes can include halogen gases and in particular HBr. HBr emitted in this way can undergo rapid atmospheric oxidation chemistry (known as the bromine-explosion) within the volcanic emission plume leading to the production of bromine oxide (BrO) and ozone depletion. In this work, we present the results of a modelling study of a volcanic eruption from Mt Etna that occurred around Christmas 2018 that lasted 6 days. The aims of this study are to demonstrate and evaluate the ability of the regional 3D Chemistry Transport Model MOCAGE to simulate the volcanic halogen chemistry in this case study, to analyse the variability of the chemical processes during the plume transport, and to quantify its impact on the composition of the troposphere at a regional scale over the Mediterranean basin.
The comparison of the tropospheric SO2 and BrO columns from 25 to 30 December 2018 from the MOCAGE simulation with the columns derived from the TROPOMI satellite measurements shows a very good agreement for the transport of the plumeand a good consistency for the concentrations if considering the uncertainties in the flux estimates and the TROPOMI columns. The analysis of the bromine species’ partitioning and of the associated chemical reaction rates provides a detailed picture of the simulated bromine chemistry throughout the diurnal cycle and at different stages of the volcanic plume’s evolution. The partitioning of the bromine species is modulated by the time evolution of the emissions during the 6 days of the eruption, by the meteorological conditions, and by the distance of the plume from the vent/the time since the emission. As the plume travels further from the vent, the halogen source gas HBr becomes depleted, BrO production in the plume becomes less efficient, and ozone depletion (proceeding via the Br + O3 reaction followed by the BrO self-reaction) decreases. The depletion of HBr relative to the other prevalent hydracid HCl leads to a shift in the relative concentrations of the Br− and Cl− ions, which in turn leads to reduced production of Br2 relative to BrCl.
The MOCAGE simulations show a regional impact of the volcanic eruption on the oxidants OH and O3 with a reduced burden of both gases that is caused by the chemistry in the volcanic plume. This reduction in atmospheric oxidation capacity results in a reduced CH4 burden. Finally, sensitivity tests on the composition of the emissions carried out in this work show that the production of BrO is higher when the volcanic emissions of sulfate aerosols are increased but occurs very slowly when no sulfate and Br radicals are assumed to be in the emissions. Both sensitivity tests highlight a significant impact on the oxidants in the troposphere at the regional scale of these assumptions.
All the results of this modelling study are consistent with the previous studies carried out on the volcanic halogens modelling.
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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
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Journal article(s) based on this preprint
Interactive discussion
Status: closed
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RC1: 'Comment on egusphere-2023-184', Anonymous Referee #1, 30 Mar 2023
Volcanoes are emitters of gaseous species (H2O, CO2 and sulfur compounds, halogen hydracids (HBr, HCl)) and aerosols into the troposphere from passive emissions and moderate volcanic eruptions, which can cause ozone loss. Modeling studies have explored this phenomenon, primarily focused on the first few hours after emission and more localized analyses. Jourdain et al. (2016) conduced the only study at a regional scale for a case of strong passive degassing at Ambryn.
This paper shows results of a new modelling study at the regional scale with the chemistry-transport model MOCAGE, focused on the Mt Etna volcanic eruption that occurred around Christmas 2018 and that lasted 6 days. The authors test the ability of the regional 3D CTM MOCAGE model to simulate the bromine-explosion cycle, to analyze the different chemical processes in the volcanic plume at different distances from the vent and to quantify its impact on the tropospheric composition at the regional scale. In other words, they analyze the variability of the chemical processes during the plume transport and quantify its impact on the composition of the troposphere at a regional scale over the Mediterranean basin.
Great paper, indeed, as it fulfills the mandates and deliverables directed by Centre National de Recherches Météorologiques of Météo-France, PREV’AIR program (Rouil et al., 2009) for France, and in the framework of the Copernicus project for Europe (Marécal et al., 2015), and for monitoring volcanic eruptions as part of the Toulouse VAAC (Volcanic Ash Advisory Center) of Météo-France – all of which converge on providing accurate and precise forecasts/model simulations of climate and air quality. Within this context, I believe this manuscript should be published in ACP. Given the substantive dataset collected and reduced, I recommend provided overarching/broader context of the implications your data – basically, over the course of the Eruption, was the air quality adversely impacted? If so/not, to what extent, quantitatively/qualitatively – especially climate and air quality @ Earth’s surface/within the boundary layer in those regions. Moreover, were their any associated human health/ecosystem/build-environment impacts associated w/ the Eruption? I also suggest considering juxtaposing Figures 2 and 3 somehow as it would be great to see them next to each other to compare TROPOMI satellite column SO2 and BrO profiles and MOCAGE model simulated column BrO and SO2 profiles. Also, the degree of congruence appears hard to interpret, especially for BrO as TROPOMI column profiles exhibit a background of BrO throughout the region (w/ slight variability in the region) and 6 days of Eruption while MOCAGE shows slight variability in distinct places w/ no excess BrO background (as shown in the TROPOMI BrO profiles). Atop this, is it possible to quantify the degree of congruence of the MOCAGE model results w/ TROPOMI satellite profiles?
Citation: https://doi.org/10.5194/egusphere-2023-184-RC1 -
AC1: 'Reply on RC1', Herizo Narivelo, 10 Jul 2023
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2023/egusphere-2023-184/egusphere-2023-184-AC1-supplement.pdf
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AC1: 'Reply on RC1', Herizo Narivelo, 10 Jul 2023
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RC2: 'Comment on egusphere-2023-184', Anonymous Referee #2, 28 Apr 2023
The manuscript presents results from a modeling study of an Etna volcanic eruption that occurred in December 2018 and lasted approximately 1 week. The objective of this study is to demonstrate and evaluate the ability of a 3D regional chemical transport model (MOCAGE) to simulate volcanic halogen chemistry. Furthermore, the impact on tropospheric composition on a regional scale over the Mediterranean region is assessed. The authors then compare the simulated tropospheric SO2 and BrO columns with those derived from TROPOMI satellite measurements and find good agreement when the uncertainties in the flux estimates and TROPOMI columns are taken into account. By analyzing the distribution of the different bromine species and the associated chemical reaction rates, the authors of this comprehensive study provide a detailed picture of the simulated bromine chemistry during the diurnal cycle and at different stages of plume development. The authors conclude that the distribution of bromine species is mainly influenced by the time evolution of emissions during the eruption, meteorological conditions, and the distance of the plume from the vent or the time since emission. Finally, the authors discuss the consequences of the obtained results in terms of the impact of the volcanic eruption on the OH and O3 oxidants at the regional scale, concluding here that the reduced concentrations lead to a decrease in the atmospheric oxidation capacity.
The effects of volcanic emissions may have important contributions to chemistry on a global scale and even more so on a regional scale. Understanding these and describing them in models is therefore important and relevant to atmospheric chemistry. The paper is written in great detail, which limits readability, but obviously offers advantages to researchers who also wish to develop such models. I therefore endorse the publication in ACP with a few minor suggested changes.
Page 2, last sentence of abstract: I don't know all the results of previous volcanic halogen modeling but the statement that the results are consistent with all previous ones seems a bit strange.
Page 2, line 31: "in the form of SO2" (there are different sulfur species but no different SO2 species)
Page 2, line 35: “magmatic gases” instead of “magmatic air” pp
Page 11, line 255: Which other cycles are meant here ?
Page 11, line 268: “….and are thus individually represented as diagnostic species” ??
Page 13, line 335: Certainly not important and just a detail: In an earlier part of the manuscript the height of Mt Etna is given as 3330 m – 50 m above would mean 3380m.
Page 20, line 439: I would not use abbreviations in the main text => molecules cm-2 s-1
Citation: https://doi.org/10.5194/egusphere-2023-184-RC2 -
AC2: 'Reply on RC2', Herizo Narivelo, 10 Jul 2023
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2023/egusphere-2023-184/egusphere-2023-184-AC2-supplement.pdf
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AC2: 'Reply on RC2', Herizo Narivelo, 10 Jul 2023
Interactive discussion
Status: closed
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RC1: 'Comment on egusphere-2023-184', Anonymous Referee #1, 30 Mar 2023
Volcanoes are emitters of gaseous species (H2O, CO2 and sulfur compounds, halogen hydracids (HBr, HCl)) and aerosols into the troposphere from passive emissions and moderate volcanic eruptions, which can cause ozone loss. Modeling studies have explored this phenomenon, primarily focused on the first few hours after emission and more localized analyses. Jourdain et al. (2016) conduced the only study at a regional scale for a case of strong passive degassing at Ambryn.
This paper shows results of a new modelling study at the regional scale with the chemistry-transport model MOCAGE, focused on the Mt Etna volcanic eruption that occurred around Christmas 2018 and that lasted 6 days. The authors test the ability of the regional 3D CTM MOCAGE model to simulate the bromine-explosion cycle, to analyze the different chemical processes in the volcanic plume at different distances from the vent and to quantify its impact on the tropospheric composition at the regional scale. In other words, they analyze the variability of the chemical processes during the plume transport and quantify its impact on the composition of the troposphere at a regional scale over the Mediterranean basin.
Great paper, indeed, as it fulfills the mandates and deliverables directed by Centre National de Recherches Météorologiques of Météo-France, PREV’AIR program (Rouil et al., 2009) for France, and in the framework of the Copernicus project for Europe (Marécal et al., 2015), and for monitoring volcanic eruptions as part of the Toulouse VAAC (Volcanic Ash Advisory Center) of Météo-France – all of which converge on providing accurate and precise forecasts/model simulations of climate and air quality. Within this context, I believe this manuscript should be published in ACP. Given the substantive dataset collected and reduced, I recommend provided overarching/broader context of the implications your data – basically, over the course of the Eruption, was the air quality adversely impacted? If so/not, to what extent, quantitatively/qualitatively – especially climate and air quality @ Earth’s surface/within the boundary layer in those regions. Moreover, were their any associated human health/ecosystem/build-environment impacts associated w/ the Eruption? I also suggest considering juxtaposing Figures 2 and 3 somehow as it would be great to see them next to each other to compare TROPOMI satellite column SO2 and BrO profiles and MOCAGE model simulated column BrO and SO2 profiles. Also, the degree of congruence appears hard to interpret, especially for BrO as TROPOMI column profiles exhibit a background of BrO throughout the region (w/ slight variability in the region) and 6 days of Eruption while MOCAGE shows slight variability in distinct places w/ no excess BrO background (as shown in the TROPOMI BrO profiles). Atop this, is it possible to quantify the degree of congruence of the MOCAGE model results w/ TROPOMI satellite profiles?
Citation: https://doi.org/10.5194/egusphere-2023-184-RC1 -
AC1: 'Reply on RC1', Herizo Narivelo, 10 Jul 2023
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2023/egusphere-2023-184/egusphere-2023-184-AC1-supplement.pdf
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AC1: 'Reply on RC1', Herizo Narivelo, 10 Jul 2023
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RC2: 'Comment on egusphere-2023-184', Anonymous Referee #2, 28 Apr 2023
The manuscript presents results from a modeling study of an Etna volcanic eruption that occurred in December 2018 and lasted approximately 1 week. The objective of this study is to demonstrate and evaluate the ability of a 3D regional chemical transport model (MOCAGE) to simulate volcanic halogen chemistry. Furthermore, the impact on tropospheric composition on a regional scale over the Mediterranean region is assessed. The authors then compare the simulated tropospheric SO2 and BrO columns with those derived from TROPOMI satellite measurements and find good agreement when the uncertainties in the flux estimates and TROPOMI columns are taken into account. By analyzing the distribution of the different bromine species and the associated chemical reaction rates, the authors of this comprehensive study provide a detailed picture of the simulated bromine chemistry during the diurnal cycle and at different stages of plume development. The authors conclude that the distribution of bromine species is mainly influenced by the time evolution of emissions during the eruption, meteorological conditions, and the distance of the plume from the vent or the time since emission. Finally, the authors discuss the consequences of the obtained results in terms of the impact of the volcanic eruption on the OH and O3 oxidants at the regional scale, concluding here that the reduced concentrations lead to a decrease in the atmospheric oxidation capacity.
The effects of volcanic emissions may have important contributions to chemistry on a global scale and even more so on a regional scale. Understanding these and describing them in models is therefore important and relevant to atmospheric chemistry. The paper is written in great detail, which limits readability, but obviously offers advantages to researchers who also wish to develop such models. I therefore endorse the publication in ACP with a few minor suggested changes.
Page 2, last sentence of abstract: I don't know all the results of previous volcanic halogen modeling but the statement that the results are consistent with all previous ones seems a bit strange.
Page 2, line 31: "in the form of SO2" (there are different sulfur species but no different SO2 species)
Page 2, line 35: “magmatic gases” instead of “magmatic air” pp
Page 11, line 255: Which other cycles are meant here ?
Page 11, line 268: “….and are thus individually represented as diagnostic species” ??
Page 13, line 335: Certainly not important and just a detail: In an earlier part of the manuscript the height of Mt Etna is given as 3330 m – 50 m above would mean 3380m.
Page 20, line 439: I would not use abbreviations in the main text => molecules cm-2 s-1
Citation: https://doi.org/10.5194/egusphere-2023-184-RC2 -
AC2: 'Reply on RC2', Herizo Narivelo, 10 Jul 2023
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2023/egusphere-2023-184/egusphere-2023-184-AC2-supplement.pdf
-
AC2: 'Reply on RC2', Herizo Narivelo, 10 Jul 2023
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Herizo Narivelo
Paul David Hamer
Virginie Marécal
Luke Surl
Tjarda Roberts
Sophie Pelletier
Béatrice Josse
Jonathan Guth
Mickaël Bacles
Simon Warnach
Thomas Wagner
Stefano Corradini
Giuseppe Salerno
Lorenzo Guerrieri
The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
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(5377 KB) - Metadata XML
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Supplement
(2025 KB) - BibTeX
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