BrO and inferred Bry profiles over the western Pacific: Relevance of inorganic bromine sources and a Bry minimum in the aged tropical tropopause layer

Theodore K. Koenig, Rainer Volkamer, Sunil Baidar, Barbara Dix, Siyuan Wang, Daniel C. Anderson, Ross J. Salawitch, Pamela A. Wales, Carlos A. Cuevas, Rafael P. Fernandez, Alfonso Saiz-Lopez, Mathew J. Evans, Tomás Sherwen, Daniel J. Jacob, Johan Schmidt, Douglas Kinnison, Jean Francois Lamarque, Eric C. Apel, James C. Bresch, Teresa CamposFrank M. Flocke, Samuel R. Hall, Shawn B. Honomichl, Rebecca Hornbrook, Jorgen B. Jensen, Richard Lueb, Denise D. Montzka, Laura L. Pan, J. Michael Reeves, Sue M. Schauffler, Kirk Ullmann, Andrew J. Weinheimer, Elliot L Atlas, Valeria Donets, Maria A. Navarro, Daniel Riemer, Nicola J. Blake, Dexian Chen, L. Gregory Huey, David J. Tanner, Thomas F. Hanisco, Glenn M. Wolfe

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

We report measurements of bromine monoxide (BrO) and use an observationally constrained chemical box model to infer total gas-phase inorganic bromine (Bry) over the tropical western Pacific Ocean (tWPO) during the CONTRAST field campaign (January-February 2014). The observed BrO and inferred Bry profiles peak in the marine boundary layer (MBL), suggesting the need for a bromine source from sea-salt aerosol (SSA), in addition to organic bromine (CBry). Both profiles are found to be C-shaped with local maxima in the upper free troposphere (FT). The median tropospheric BrO vertical column density (VCD) was measured as 1.6×1013 molec cm-2, compared to model predictions of 0.9×1013 molec cm-2 in GEOS-Chem (CBry but no SSA source), 0.4×1013 molec cm-2 in CAM-Chem (CBry and SSA), and 2.1×1013 molec cm-2 in GEOS-Chem (CBry and SSA). Neither global model fully captures the C-shape of the Bry profile. A local Bry maximum of 3.6 ppt (2.9-4.4 ppt; 95 % confidence interval, CI) is inferred between 9.5 and 13.5 km in air masses influenced by recent convective outflow. Unlike BrO, which increases from the convective tropical tropopause layer (TTL) to the aged TTL, gas-phase Bry decreases from the convective TTL to the aged TTL. Analysis of gas-phase Bry against multiple tracers (CFC-11, H2O-O3 ratio, and potential temperature) reveals a Bry minimum of 2.7 ppt (2.3-3.1 ppt; 95 % CI) in the aged TTL, which agrees closely with a stratospheric injection of 2.6 ± 0.6 ppt of inorganic Bry (estimated from CFC-11 correlations), and is remarkably insensitive to assumptions about heterogeneous chemistry. Bry increases to 6.3 ppt (5.6-7.0 ppt; 95 % CI) in the stratospheric "middleworld" and 6.9 ppt (6.5-7.3 ppt; 95 % CI) in the stratospheric "overworld". The local Bry minimum in the aged TTL is qualitatively (but not quantitatively) captured by CAM-Chem, and suggests a more complex partitioning of gas-phase and aerosol Bry species than previously recognized. Our data provide corroborating evidence that inorganic bromine sources (e.g., SSA-derived gas-phase Bry) are needed to explain the gas-phase Bry budget in the upper free troposphere and TTL. They are also consistent with observations of significant bromide in Upper Troposphere-Lower Stratosphere aerosols. The total Bry budget in the TTL is currently not closed, because of the lack of concurrent quantitative measurements of gas-phase Bry species (i.e., BrO, HOBr, HBr, etc.) and aerosol bromide. Such simultaneous measurements are needed to (1) quantify SSA-derived Bry in the upper FT, (2) test Bry partitioning, and possibly explain the gas-phase Bry minimum in the aged TTL, (3) constrain heterogeneous reaction rates of bromine, and (4) account for all of the sources of Bry to the lower stratosphere.

Original languageEnglish (US)
Pages (from-to)15245-15270
Number of pages26
JournalAtmospheric Chemistry and Physics
Volume17
Issue number24
DOIs
StatePublished - Dec 22 2017

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bromine
tropopause
sea salt
aerosol
gas
troposphere
CFC
EOS
bromide
stratosphere
partitioning
potential temperature
air mass
reaction rate
confidence interval
outflow
boundary layer
tracer

ASJC Scopus subject areas

  • Atmospheric Science

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BrO and inferred Bry profiles over the western Pacific : Relevance of inorganic bromine sources and a Bry minimum in the aged tropical tropopause layer. / Koenig, Theodore K.; Volkamer, Rainer; Baidar, Sunil; Dix, Barbara; Wang, Siyuan; Anderson, Daniel C.; Salawitch, Ross J.; Wales, Pamela A.; Cuevas, Carlos A.; Fernandez, Rafael P.; Saiz-Lopez, Alfonso; Evans, Mathew J.; Sherwen, Tomás; Jacob, Daniel J.; Schmidt, Johan; Kinnison, Douglas; Lamarque, Jean Francois; Apel, Eric C.; Bresch, James C.; Campos, Teresa; Flocke, Frank M.; Hall, Samuel R.; Honomichl, Shawn B.; Hornbrook, Rebecca; Jensen, Jorgen B.; Lueb, Richard; Montzka, Denise D.; Pan, Laura L.; Michael Reeves, J.; Schauffler, Sue M.; Ullmann, Kirk; Weinheimer, Andrew J.; Atlas, Elliot L; Donets, Valeria; Navarro, Maria A.; Riemer, Daniel; Blake, Nicola J.; Chen, Dexian; Gregory Huey, L.; Tanner, David J.; Hanisco, Thomas F.; Wolfe, Glenn M.

In: Atmospheric Chemistry and Physics, Vol. 17, No. 24, 22.12.2017, p. 15245-15270.

Research output: Contribution to journalArticle

Koenig, TK, Volkamer, R, Baidar, S, Dix, B, Wang, S, Anderson, DC, Salawitch, RJ, Wales, PA, Cuevas, CA, Fernandez, RP, Saiz-Lopez, A, Evans, MJ, Sherwen, T, Jacob, DJ, Schmidt, J, Kinnison, D, Lamarque, JF, Apel, EC, Bresch, JC, Campos, T, Flocke, FM, Hall, SR, Honomichl, SB, Hornbrook, R, Jensen, JB, Lueb, R, Montzka, DD, Pan, LL, Michael Reeves, J, Schauffler, SM, Ullmann, K, Weinheimer, AJ, Atlas, EL, Donets, V, Navarro, MA, Riemer, D, Blake, NJ, Chen, D, Gregory Huey, L, Tanner, DJ, Hanisco, TF & Wolfe, GM 2017, 'BrO and inferred Bry profiles over the western Pacific: Relevance of inorganic bromine sources and a Bry minimum in the aged tropical tropopause layer', Atmospheric Chemistry and Physics, vol. 17, no. 24, pp. 15245-15270. https://doi.org/10.5194/acp-17-15245-2017
Koenig, Theodore K. ; Volkamer, Rainer ; Baidar, Sunil ; Dix, Barbara ; Wang, Siyuan ; Anderson, Daniel C. ; Salawitch, Ross J. ; Wales, Pamela A. ; Cuevas, Carlos A. ; Fernandez, Rafael P. ; Saiz-Lopez, Alfonso ; Evans, Mathew J. ; Sherwen, Tomás ; Jacob, Daniel J. ; Schmidt, Johan ; Kinnison, Douglas ; Lamarque, Jean Francois ; Apel, Eric C. ; Bresch, James C. ; Campos, Teresa ; Flocke, Frank M. ; Hall, Samuel R. ; Honomichl, Shawn B. ; Hornbrook, Rebecca ; Jensen, Jorgen B. ; Lueb, Richard ; Montzka, Denise D. ; Pan, Laura L. ; Michael Reeves, J. ; Schauffler, Sue M. ; Ullmann, Kirk ; Weinheimer, Andrew J. ; Atlas, Elliot L ; Donets, Valeria ; Navarro, Maria A. ; Riemer, Daniel ; Blake, Nicola J. ; Chen, Dexian ; Gregory Huey, L. ; Tanner, David J. ; Hanisco, Thomas F. ; Wolfe, Glenn M. / BrO and inferred Bry profiles over the western Pacific : Relevance of inorganic bromine sources and a Bry minimum in the aged tropical tropopause layer. In: Atmospheric Chemistry and Physics. 2017 ; Vol. 17, No. 24. pp. 15245-15270.
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title = "BrO and inferred Bry profiles over the western Pacific: Relevance of inorganic bromine sources and a Bry minimum in the aged tropical tropopause layer",
abstract = "We report measurements of bromine monoxide (BrO) and use an observationally constrained chemical box model to infer total gas-phase inorganic bromine (Bry) over the tropical western Pacific Ocean (tWPO) during the CONTRAST field campaign (January-February 2014). The observed BrO and inferred Bry profiles peak in the marine boundary layer (MBL), suggesting the need for a bromine source from sea-salt aerosol (SSA), in addition to organic bromine (CBry). Both profiles are found to be C-shaped with local maxima in the upper free troposphere (FT). The median tropospheric BrO vertical column density (VCD) was measured as 1.6×1013 molec cm-2, compared to model predictions of 0.9×1013 molec cm-2 in GEOS-Chem (CBry but no SSA source), 0.4×1013 molec cm-2 in CAM-Chem (CBry and SSA), and 2.1×1013 molec cm-2 in GEOS-Chem (CBry and SSA). Neither global model fully captures the C-shape of the Bry profile. A local Bry maximum of 3.6 ppt (2.9-4.4 ppt; 95 {\%} confidence interval, CI) is inferred between 9.5 and 13.5 km in air masses influenced by recent convective outflow. Unlike BrO, which increases from the convective tropical tropopause layer (TTL) to the aged TTL, gas-phase Bry decreases from the convective TTL to the aged TTL. Analysis of gas-phase Bry against multiple tracers (CFC-11, H2O-O3 ratio, and potential temperature) reveals a Bry minimum of 2.7 ppt (2.3-3.1 ppt; 95 {\%} CI) in the aged TTL, which agrees closely with a stratospheric injection of 2.6 ± 0.6 ppt of inorganic Bry (estimated from CFC-11 correlations), and is remarkably insensitive to assumptions about heterogeneous chemistry. Bry increases to 6.3 ppt (5.6-7.0 ppt; 95 {\%} CI) in the stratospheric {"}middleworld{"} and 6.9 ppt (6.5-7.3 ppt; 95 {\%} CI) in the stratospheric {"}overworld{"}. The local Bry minimum in the aged TTL is qualitatively (but not quantitatively) captured by CAM-Chem, and suggests a more complex partitioning of gas-phase and aerosol Bry species than previously recognized. Our data provide corroborating evidence that inorganic bromine sources (e.g., SSA-derived gas-phase Bry) are needed to explain the gas-phase Bry budget in the upper free troposphere and TTL. They are also consistent with observations of significant bromide in Upper Troposphere-Lower Stratosphere aerosols. The total Bry budget in the TTL is currently not closed, because of the lack of concurrent quantitative measurements of gas-phase Bry species (i.e., BrO, HOBr, HBr, etc.) and aerosol bromide. Such simultaneous measurements are needed to (1) quantify SSA-derived Bry in the upper FT, (2) test Bry partitioning, and possibly explain the gas-phase Bry minimum in the aged TTL, (3) constrain heterogeneous reaction rates of bromine, and (4) account for all of the sources of Bry to the lower stratosphere.",
author = "Koenig, {Theodore K.} and Rainer Volkamer and Sunil Baidar and Barbara Dix and Siyuan Wang and Anderson, {Daniel C.} and Salawitch, {Ross J.} and Wales, {Pamela A.} and Cuevas, {Carlos A.} and Fernandez, {Rafael P.} and Alfonso Saiz-Lopez and Evans, {Mathew J.} and Tom{\'a}s Sherwen and Jacob, {Daniel J.} and Johan Schmidt and Douglas Kinnison and Lamarque, {Jean Francois} and Apel, {Eric C.} and Bresch, {James C.} and Teresa Campos and Flocke, {Frank M.} and Hall, {Samuel R.} and Honomichl, {Shawn B.} and Rebecca Hornbrook and Jensen, {Jorgen B.} and Richard Lueb and Montzka, {Denise D.} and Pan, {Laura L.} and {Michael Reeves}, J. and Schauffler, {Sue M.} and Kirk Ullmann and Weinheimer, {Andrew J.} and Atlas, {Elliot L} and Valeria Donets and Navarro, {Maria A.} and Daniel Riemer and Blake, {Nicola J.} and Dexian Chen and {Gregory Huey}, L. and Tanner, {David J.} and Hanisco, {Thomas F.} and Wolfe, {Glenn M.}",
year = "2017",
month = "12",
day = "22",
doi = "10.5194/acp-17-15245-2017",
language = "English (US)",
volume = "17",
pages = "15245--15270",
journal = "Atmospheric Chemistry and Physics",
issn = "1680-7316",
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TY - JOUR

T1 - BrO and inferred Bry profiles over the western Pacific

T2 - Relevance of inorganic bromine sources and a Bry minimum in the aged tropical tropopause layer

AU - Koenig, Theodore K.

AU - Volkamer, Rainer

AU - Baidar, Sunil

AU - Dix, Barbara

AU - Wang, Siyuan

AU - Anderson, Daniel C.

AU - Salawitch, Ross J.

AU - Wales, Pamela A.

AU - Cuevas, Carlos A.

AU - Fernandez, Rafael P.

AU - Saiz-Lopez, Alfonso

AU - Evans, Mathew J.

AU - Sherwen, Tomás

AU - Jacob, Daniel J.

AU - Schmidt, Johan

AU - Kinnison, Douglas

AU - Lamarque, Jean Francois

AU - Apel, Eric C.

AU - Bresch, James C.

AU - Campos, Teresa

AU - Flocke, Frank M.

AU - Hall, Samuel R.

AU - Honomichl, Shawn B.

AU - Hornbrook, Rebecca

AU - Jensen, Jorgen B.

AU - Lueb, Richard

AU - Montzka, Denise D.

AU - Pan, Laura L.

AU - Michael Reeves, J.

AU - Schauffler, Sue M.

AU - Ullmann, Kirk

AU - Weinheimer, Andrew J.

AU - Atlas, Elliot L

AU - Donets, Valeria

AU - Navarro, Maria A.

AU - Riemer, Daniel

AU - Blake, Nicola J.

AU - Chen, Dexian

AU - Gregory Huey, L.

AU - Tanner, David J.

AU - Hanisco, Thomas F.

AU - Wolfe, Glenn M.

PY - 2017/12/22

Y1 - 2017/12/22

N2 - We report measurements of bromine monoxide (BrO) and use an observationally constrained chemical box model to infer total gas-phase inorganic bromine (Bry) over the tropical western Pacific Ocean (tWPO) during the CONTRAST field campaign (January-February 2014). The observed BrO and inferred Bry profiles peak in the marine boundary layer (MBL), suggesting the need for a bromine source from sea-salt aerosol (SSA), in addition to organic bromine (CBry). Both profiles are found to be C-shaped with local maxima in the upper free troposphere (FT). The median tropospheric BrO vertical column density (VCD) was measured as 1.6×1013 molec cm-2, compared to model predictions of 0.9×1013 molec cm-2 in GEOS-Chem (CBry but no SSA source), 0.4×1013 molec cm-2 in CAM-Chem (CBry and SSA), and 2.1×1013 molec cm-2 in GEOS-Chem (CBry and SSA). Neither global model fully captures the C-shape of the Bry profile. A local Bry maximum of 3.6 ppt (2.9-4.4 ppt; 95 % confidence interval, CI) is inferred between 9.5 and 13.5 km in air masses influenced by recent convective outflow. Unlike BrO, which increases from the convective tropical tropopause layer (TTL) to the aged TTL, gas-phase Bry decreases from the convective TTL to the aged TTL. Analysis of gas-phase Bry against multiple tracers (CFC-11, H2O-O3 ratio, and potential temperature) reveals a Bry minimum of 2.7 ppt (2.3-3.1 ppt; 95 % CI) in the aged TTL, which agrees closely with a stratospheric injection of 2.6 ± 0.6 ppt of inorganic Bry (estimated from CFC-11 correlations), and is remarkably insensitive to assumptions about heterogeneous chemistry. Bry increases to 6.3 ppt (5.6-7.0 ppt; 95 % CI) in the stratospheric "middleworld" and 6.9 ppt (6.5-7.3 ppt; 95 % CI) in the stratospheric "overworld". The local Bry minimum in the aged TTL is qualitatively (but not quantitatively) captured by CAM-Chem, and suggests a more complex partitioning of gas-phase and aerosol Bry species than previously recognized. Our data provide corroborating evidence that inorganic bromine sources (e.g., SSA-derived gas-phase Bry) are needed to explain the gas-phase Bry budget in the upper free troposphere and TTL. They are also consistent with observations of significant bromide in Upper Troposphere-Lower Stratosphere aerosols. The total Bry budget in the TTL is currently not closed, because of the lack of concurrent quantitative measurements of gas-phase Bry species (i.e., BrO, HOBr, HBr, etc.) and aerosol bromide. Such simultaneous measurements are needed to (1) quantify SSA-derived Bry in the upper FT, (2) test Bry partitioning, and possibly explain the gas-phase Bry minimum in the aged TTL, (3) constrain heterogeneous reaction rates of bromine, and (4) account for all of the sources of Bry to the lower stratosphere.

AB - We report measurements of bromine monoxide (BrO) and use an observationally constrained chemical box model to infer total gas-phase inorganic bromine (Bry) over the tropical western Pacific Ocean (tWPO) during the CONTRAST field campaign (January-February 2014). The observed BrO and inferred Bry profiles peak in the marine boundary layer (MBL), suggesting the need for a bromine source from sea-salt aerosol (SSA), in addition to organic bromine (CBry). Both profiles are found to be C-shaped with local maxima in the upper free troposphere (FT). The median tropospheric BrO vertical column density (VCD) was measured as 1.6×1013 molec cm-2, compared to model predictions of 0.9×1013 molec cm-2 in GEOS-Chem (CBry but no SSA source), 0.4×1013 molec cm-2 in CAM-Chem (CBry and SSA), and 2.1×1013 molec cm-2 in GEOS-Chem (CBry and SSA). Neither global model fully captures the C-shape of the Bry profile. A local Bry maximum of 3.6 ppt (2.9-4.4 ppt; 95 % confidence interval, CI) is inferred between 9.5 and 13.5 km in air masses influenced by recent convective outflow. Unlike BrO, which increases from the convective tropical tropopause layer (TTL) to the aged TTL, gas-phase Bry decreases from the convective TTL to the aged TTL. Analysis of gas-phase Bry against multiple tracers (CFC-11, H2O-O3 ratio, and potential temperature) reveals a Bry minimum of 2.7 ppt (2.3-3.1 ppt; 95 % CI) in the aged TTL, which agrees closely with a stratospheric injection of 2.6 ± 0.6 ppt of inorganic Bry (estimated from CFC-11 correlations), and is remarkably insensitive to assumptions about heterogeneous chemistry. Bry increases to 6.3 ppt (5.6-7.0 ppt; 95 % CI) in the stratospheric "middleworld" and 6.9 ppt (6.5-7.3 ppt; 95 % CI) in the stratospheric "overworld". The local Bry minimum in the aged TTL is qualitatively (but not quantitatively) captured by CAM-Chem, and suggests a more complex partitioning of gas-phase and aerosol Bry species than previously recognized. Our data provide corroborating evidence that inorganic bromine sources (e.g., SSA-derived gas-phase Bry) are needed to explain the gas-phase Bry budget in the upper free troposphere and TTL. They are also consistent with observations of significant bromide in Upper Troposphere-Lower Stratosphere aerosols. The total Bry budget in the TTL is currently not closed, because of the lack of concurrent quantitative measurements of gas-phase Bry species (i.e., BrO, HOBr, HBr, etc.) and aerosol bromide. Such simultaneous measurements are needed to (1) quantify SSA-derived Bry in the upper FT, (2) test Bry partitioning, and possibly explain the gas-phase Bry minimum in the aged TTL, (3) constrain heterogeneous reaction rates of bromine, and (4) account for all of the sources of Bry to the lower stratosphere.

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