Effect of sea salt aerosol on tropospheric bromine chemistry
<p>Bromine radicals influence global tropospheric chemistry by depleting ozone and by oxidizing elemental mercury and reduced sulfur species. Observations typically indicate a 50 % depletion of sea salt aerosol (SSA) bromide relative to seawater composition, implying that SSA debrom...
| Main Authors: | , , , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2019-05-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://www.atmos-chem-phys.net/19/6497/2019/acp-19-6497-2019.pdf |
| id |
doaj-a60a789329c547f688f00b67c1571ab3 |
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| record_format |
Article |
| collection |
DOAJ |
| language |
English |
| format |
Article |
| sources |
DOAJ |
| author |
L. Zhu D. J. Jacob D. J. Jacob S. D. Eastham M. P. Sulprizio X. Wang T. Sherwen T. Sherwen M. J. Evans M. J. Evans Q. Chen Q. Chen B. Alexander T. K. Koenig T. K. Koenig R. Volkamer R. Volkamer L. G. Huey M. Le Breton M. Le Breton T. J. Bannan C. J. Percival C. J. Percival |
| spellingShingle |
L. Zhu D. J. Jacob D. J. Jacob S. D. Eastham M. P. Sulprizio X. Wang T. Sherwen T. Sherwen M. J. Evans M. J. Evans Q. Chen Q. Chen B. Alexander T. K. Koenig T. K. Koenig R. Volkamer R. Volkamer L. G. Huey M. Le Breton M. Le Breton T. J. Bannan C. J. Percival C. J. Percival Effect of sea salt aerosol on tropospheric bromine chemistry Atmospheric Chemistry and Physics |
| author_facet |
L. Zhu D. J. Jacob D. J. Jacob S. D. Eastham M. P. Sulprizio X. Wang T. Sherwen T. Sherwen M. J. Evans M. J. Evans Q. Chen Q. Chen B. Alexander T. K. Koenig T. K. Koenig R. Volkamer R. Volkamer L. G. Huey M. Le Breton M. Le Breton T. J. Bannan C. J. Percival C. J. Percival |
| author_sort |
L. Zhu |
| title |
Effect of sea salt aerosol on tropospheric bromine chemistry |
| title_short |
Effect of sea salt aerosol on tropospheric bromine chemistry |
| title_full |
Effect of sea salt aerosol on tropospheric bromine chemistry |
| title_fullStr |
Effect of sea salt aerosol on tropospheric bromine chemistry |
| title_full_unstemmed |
Effect of sea salt aerosol on tropospheric bromine chemistry |
| title_sort |
effect of sea salt aerosol on tropospheric bromine chemistry |
| publisher |
Copernicus Publications |
| series |
Atmospheric Chemistry and Physics |
| issn |
1680-7316 1680-7324 |
| publishDate |
2019-05-01 |
| description |
<p>Bromine radicals influence global tropospheric chemistry
by depleting ozone and by oxidizing elemental mercury and reduced sulfur
species. Observations typically indicate a 50 % depletion of sea salt
aerosol (SSA) bromide relative to seawater composition, implying that SSA
debromination could be the dominant global source of tropospheric bromine.
However, it has been difficult to reconcile this large source with the
relatively low bromine monoxide (BrO) mixing ratios observed in the marine
boundary layer (MBL). Here we present a new mechanistic description of SSA
debromination in the GEOS-Chem global atmospheric chemistry model with a
detailed representation of halogen (Cl, Br, and I) chemistry. We show that
observed levels of SSA debromination can be reproduced in a manner
consistent with observed BrO mixing ratios. Bromine radical sinks from the
HOBr <span class="inline-formula">+</span> S(IV) heterogeneous reactions and from ocean emission of
acetaldehyde are critical in moderating tropospheric BrO levels. The
resulting HBr is rapidly taken up by SSA and also deposited. Observations of SSA debromination at southern midlatitudes in summer suggest that model
uptake of HBr by SSA may be too fast. The model provides a successful
simulation of free-tropospheric BrO in the tropics and midlatitudes in summer,
where the bromine radical sink from the HOBr <span class="inline-formula">+</span> S(IV) reactions is
compensated for by more efficient HOBr-driven recycling in clouds compared to
previous GEOS-Chem versions. Simulated BrO in the MBL is generally much
higher in winter than in summer due to a combination of greater SSA emission
and slower conversion of bromine radicals to HBr. An outstanding issue in
the model is the overestimate of free-tropospheric BrO in extratropical
winter–spring, possibly reflecting an overestimate of the <span class="inline-formula">HOBr∕HBr</span> ratio
under these conditions where the dominant HOBr source is hydrolysis of
<span class="inline-formula">BrNO<sub>3</sub></span>.</p> |
| url |
https://www.atmos-chem-phys.net/19/6497/2019/acp-19-6497-2019.pdf |
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doaj-a60a789329c547f688f00b67c1571ab32020-11-24T21:21:43ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242019-05-01196497650710.5194/acp-19-6497-2019Effect of sea salt aerosol on tropospheric bromine chemistryL. Zhu0D. J. Jacob1D. J. Jacob2S. D. Eastham3M. P. Sulprizio4X. Wang5T. Sherwen6T. Sherwen7M. J. Evans8M. J. Evans9Q. Chen10Q. Chen11B. Alexander12T. K. Koenig13T. K. Koenig14R. Volkamer15R. Volkamer16L. G. Huey17M. Le Breton18M. Le Breton19T. J. Bannan20C. J. Percival21C. J. Percival22John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USAJohn A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USADepartment of Earth and Planetary Sciences, Harvard University, Cambridge, MA, USALaboratory for Aviation and the Environment, Massachusetts Institute of Technology, Cambridge, MA, USAJohn A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USAJohn A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USAWolfson Atmospheric Chemistry Laboratories, Department of Chemistry, University of York, York, UKNational Centre for Atmospheric Science (NCAS), University of York, York, UKWolfson Atmospheric Chemistry Laboratories, Department of Chemistry, University of York, York, UKNational Centre for Atmospheric Science (NCAS), University of York, York, UKDepartment of Atmospheric Sciences, University of Washington, Seattle, WA, USAnow at: Department of Chemistry, University of Michigan, Ann Arbor, MI, USADepartment of Atmospheric Sciences, University of Washington, Seattle, WA, USADepartment of Chemistry, University of Colorado, Boulder, CO, USACooperative Institute for Research in Environmental Sciences (CIRES), Boulder, CO, USADepartment of Chemistry, University of Colorado, Boulder, CO, USACooperative Institute for Research in Environmental Sciences (CIRES), Boulder, CO, USASchool of Earth and Atmospheric Sciences, Georgia Tech, Atlanta, Georgia, USAThe Centre for Atmospheric Science, School of Earth, Atmospheric and Environmental Sciences, University of Manchester, Simon Building, Brunswick Street, Manchester M13 9PL, UKDepartment of Chemistry and Molecular Biology, University of Gothenburg, Medicinaregatan 9 C, 40530 Gothenburg, SwedenThe Centre for Atmospheric Science, School of Earth, Atmospheric and Environmental Sciences, University of Manchester, Simon Building, Brunswick Street, Manchester M13 9PL, UKThe Centre for Atmospheric Science, School of Earth, Atmospheric and Environmental Sciences, University of Manchester, Simon Building, Brunswick Street, Manchester M13 9PL, UKnow at: Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA, USA<p>Bromine radicals influence global tropospheric chemistry by depleting ozone and by oxidizing elemental mercury and reduced sulfur species. Observations typically indicate a 50 % depletion of sea salt aerosol (SSA) bromide relative to seawater composition, implying that SSA debromination could be the dominant global source of tropospheric bromine. However, it has been difficult to reconcile this large source with the relatively low bromine monoxide (BrO) mixing ratios observed in the marine boundary layer (MBL). Here we present a new mechanistic description of SSA debromination in the GEOS-Chem global atmospheric chemistry model with a detailed representation of halogen (Cl, Br, and I) chemistry. We show that observed levels of SSA debromination can be reproduced in a manner consistent with observed BrO mixing ratios. Bromine radical sinks from the HOBr <span class="inline-formula">+</span> S(IV) heterogeneous reactions and from ocean emission of acetaldehyde are critical in moderating tropospheric BrO levels. The resulting HBr is rapidly taken up by SSA and also deposited. Observations of SSA debromination at southern midlatitudes in summer suggest that model uptake of HBr by SSA may be too fast. The model provides a successful simulation of free-tropospheric BrO in the tropics and midlatitudes in summer, where the bromine radical sink from the HOBr <span class="inline-formula">+</span> S(IV) reactions is compensated for by more efficient HOBr-driven recycling in clouds compared to previous GEOS-Chem versions. Simulated BrO in the MBL is generally much higher in winter than in summer due to a combination of greater SSA emission and slower conversion of bromine radicals to HBr. An outstanding issue in the model is the overestimate of free-tropospheric BrO in extratropical winter–spring, possibly reflecting an overestimate of the <span class="inline-formula">HOBr∕HBr</span> ratio under these conditions where the dominant HOBr source is hydrolysis of <span class="inline-formula">BrNO<sub>3</sub></span>.</p>https://www.atmos-chem-phys.net/19/6497/2019/acp-19-6497-2019.pdf |