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Importance of reactive halogens in the tropical marine atmosphere: A regional modelling study using WRF-Chem

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Importance of reactive halogens in the tropical marine atmosphere: A regional modelling study using WRF-Chem. / Badia Moragas, Alba; Reeves, Claire; Baker, Alexander; Saiz Lopez, Alfonso; Volkamer, Rainer; Koenig, Theodore K.; Apel, Eric C.; Hornbrook, Rebecca S.; Carpenter, Lucy J.; Andrews, Stephen J.; Von Glasow, Roland.

In: Atmospheric Chemistry and Physics, Vol. 19, No. 5, 12.03.2019, p. 3161–3189.

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Badia Moragas, A, Reeves, C, Baker, A, Saiz Lopez, A, Volkamer, R, Koenig, TK, Apel, EC, Hornbrook, RS, Carpenter, LJ, Andrews, SJ & Von Glasow, R 2019, 'Importance of reactive halogens in the tropical marine atmosphere: A regional modelling study using WRF-Chem' Atmospheric Chemistry and Physics, vol. 19, no. 5, pp. 3161–3189. https://doi.org/10.5194/acp-19-3161-2019

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Badia Moragas, Alba ; Reeves, Claire ; Baker, Alexander ; Saiz Lopez, Alfonso ; Volkamer, Rainer ; Koenig, Theodore K. ; Apel, Eric C. ; Hornbrook, Rebecca S. ; Carpenter, Lucy J. ; Andrews, Stephen J. ; Von Glasow, Roland. / Importance of reactive halogens in the tropical marine atmosphere: A regional modelling study using WRF-Chem. In: Atmospheric Chemistry and Physics. 2019 ; Vol. 19, No. 5. pp. 3161–3189.

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@article{bab341ed7a434ad2befaa6f08d3164ea,
title = "Importance of reactive halogens in the tropical marine atmosphere: A regional modelling study using WRF-Chem",
abstract = "This study investigates the impact of halogens on atmospheric chemistry in the tropical troposphere and explores the sensitivity of this to uncertainties in the fluxes of halogens to the atmosphere and the chemical processing. To do this the regional chemistry transport model WRF-Chem has been extended, for the first time, to include halogen chemistry (bromine, chlorine and iodine chemistry), including heterogeneous recycling reactions involving sea-salt aerosol and other particles, reactions of Br with volatile organic compounds (VOCs), along with oceanic emissions of halocarbons, VOCs and inorganic iodine. The study focuses on the tropical East Pacific using field observations from the TORERO campaign (January-February 2012) to evaluate the model performance.Including all the new processes, the model does a reasonable job reproducing the observed mixing ratios of BrO and IO, albeit with some discrepancies, some of which can be attributed to difficulties in the model’s ability to reproduce the observed halocarbons. This is somewhat expected given the large uncertainties in the air-sea fluxes of the halocarbons in a region where there are few observations of seawater concentrations. We see a considerable impact on the Bry partitioning when heterogeneous chemistry is included, with a greater proportion of the Bry in active forms such as BrO, HOBr and dihalogens. Including debromination of sea-salt increases BrO slightly throughout the free troposphere, but in the tropical marine boundary layer, where the sea-salt particles are plentiful and relatively acidic, debromination leads to overestimation of the observed BrO. However, it should be noted that the modelled BrO was extremely sensitive to the inclusion of reactions between Br and the VOCs, which convert Br to HBr, a far less reactive form of Bry. Excluding these reactions leads to modelled BrO mixing ratios greater than observed. The reactions between Br and aldehydes were found to be particularly important, despite the model underestimating the amount of aldehydes observed in the atmosphere. There are only small changes to Iy partitioning and IO when the heterogeneous reactions, primarly on sea-salt, are included.Our model results show that the tropospheric Ox loss due to halogens is 31{\%}. This loss is mostly due to I (16{\%}) and Br (14{\%}) and it is in good agreement with other estimates from state-of-the-art atmospheric chemistry models.",
author = "{Badia Moragas}, Alba and Claire Reeves and Alexander Baker and {Saiz Lopez}, Alfonso and Rainer Volkamer and Koenig, {Theodore K.} and Apel, {Eric C.} and Hornbrook, {Rebecca S.} and Carpenter, {Lucy J.} and Andrews, {Stephen J.} and {Von Glasow}, Roland",
year = "2019",
month = "3",
day = "12",
doi = "10.5194/acp-19-3161-2019",
language = "English",
volume = "19",
pages = "3161–3189",
journal = "Atmospheric Chemistry and Physics",
issn = "1680-7324",
publisher = "European Geosciences Union",
number = "5",

}

RIS (suitable for import to EndNote) - Download

TY - JOUR

T1 - Importance of reactive halogens in the tropical marine atmosphere: A regional modelling study using WRF-Chem

AU - Badia Moragas, Alba

AU - Reeves, Claire

AU - Baker, Alexander

AU - Saiz Lopez, Alfonso

AU - Volkamer, Rainer

AU - Koenig, Theodore K.

AU - Apel, Eric C.

AU - Hornbrook, Rebecca S.

AU - Carpenter, Lucy J.

AU - Andrews, Stephen J.

AU - Von Glasow, Roland

PY - 2019/3/12

Y1 - 2019/3/12

N2 - This study investigates the impact of halogens on atmospheric chemistry in the tropical troposphere and explores the sensitivity of this to uncertainties in the fluxes of halogens to the atmosphere and the chemical processing. To do this the regional chemistry transport model WRF-Chem has been extended, for the first time, to include halogen chemistry (bromine, chlorine and iodine chemistry), including heterogeneous recycling reactions involving sea-salt aerosol and other particles, reactions of Br with volatile organic compounds (VOCs), along with oceanic emissions of halocarbons, VOCs and inorganic iodine. The study focuses on the tropical East Pacific using field observations from the TORERO campaign (January-February 2012) to evaluate the model performance.Including all the new processes, the model does a reasonable job reproducing the observed mixing ratios of BrO and IO, albeit with some discrepancies, some of which can be attributed to difficulties in the model’s ability to reproduce the observed halocarbons. This is somewhat expected given the large uncertainties in the air-sea fluxes of the halocarbons in a region where there are few observations of seawater concentrations. We see a considerable impact on the Bry partitioning when heterogeneous chemistry is included, with a greater proportion of the Bry in active forms such as BrO, HOBr and dihalogens. Including debromination of sea-salt increases BrO slightly throughout the free troposphere, but in the tropical marine boundary layer, where the sea-salt particles are plentiful and relatively acidic, debromination leads to overestimation of the observed BrO. However, it should be noted that the modelled BrO was extremely sensitive to the inclusion of reactions between Br and the VOCs, which convert Br to HBr, a far less reactive form of Bry. Excluding these reactions leads to modelled BrO mixing ratios greater than observed. The reactions between Br and aldehydes were found to be particularly important, despite the model underestimating the amount of aldehydes observed in the atmosphere. There are only small changes to Iy partitioning and IO when the heterogeneous reactions, primarly on sea-salt, are included.Our model results show that the tropospheric Ox loss due to halogens is 31%. This loss is mostly due to I (16%) and Br (14%) and it is in good agreement with other estimates from state-of-the-art atmospheric chemistry models.

AB - This study investigates the impact of halogens on atmospheric chemistry in the tropical troposphere and explores the sensitivity of this to uncertainties in the fluxes of halogens to the atmosphere and the chemical processing. To do this the regional chemistry transport model WRF-Chem has been extended, for the first time, to include halogen chemistry (bromine, chlorine and iodine chemistry), including heterogeneous recycling reactions involving sea-salt aerosol and other particles, reactions of Br with volatile organic compounds (VOCs), along with oceanic emissions of halocarbons, VOCs and inorganic iodine. The study focuses on the tropical East Pacific using field observations from the TORERO campaign (January-February 2012) to evaluate the model performance.Including all the new processes, the model does a reasonable job reproducing the observed mixing ratios of BrO and IO, albeit with some discrepancies, some of which can be attributed to difficulties in the model’s ability to reproduce the observed halocarbons. This is somewhat expected given the large uncertainties in the air-sea fluxes of the halocarbons in a region where there are few observations of seawater concentrations. We see a considerable impact on the Bry partitioning when heterogeneous chemistry is included, with a greater proportion of the Bry in active forms such as BrO, HOBr and dihalogens. Including debromination of sea-salt increases BrO slightly throughout the free troposphere, but in the tropical marine boundary layer, where the sea-salt particles are plentiful and relatively acidic, debromination leads to overestimation of the observed BrO. However, it should be noted that the modelled BrO was extremely sensitive to the inclusion of reactions between Br and the VOCs, which convert Br to HBr, a far less reactive form of Bry. Excluding these reactions leads to modelled BrO mixing ratios greater than observed. The reactions between Br and aldehydes were found to be particularly important, despite the model underestimating the amount of aldehydes observed in the atmosphere. There are only small changes to Iy partitioning and IO when the heterogeneous reactions, primarly on sea-salt, are included.Our model results show that the tropospheric Ox loss due to halogens is 31%. This loss is mostly due to I (16%) and Br (14%) and it is in good agreement with other estimates from state-of-the-art atmospheric chemistry models.

U2 - 10.5194/acp-19-3161-2019

DO - 10.5194/acp-19-3161-2019

M3 - Article

VL - 19

SP - 3161

EP - 3189

JO - Atmospheric Chemistry and Physics

JF - Atmospheric Chemistry and Physics

SN - 1680-7324

IS - 5

ER -

ID: 150138868