Consistent simulation of bromine chemistry from the marine boundary layer to the stratosphere – Part 2: Bromocarbons

Kerkweg, Astrid; Jöckel, Patrick; Warwick, N. J.; Gebhardt, S.; Brenninkmeijer, Carl A. M.; Lelieveld, J.

doi:10.5194/acp-8-5919-2008

Cited by 54 publications

(78 citation statements)

References 67 publications

(101 reference statements)

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“…This implies that the 280 Gg Br yr −1 tropical coastal emissions used in Scenario C is likely too high. This agrees with the results from Kerkweg et al (2008) who found that with emission Scenario 5 from Warwick et al (2006) (Scenario C in the study), the simulated CHBr 3 is too high compared to observations in the UT/LS.…”

Section: Impact Of Emissionsupporting

confidence: 82%

“…Degradation of CH 2 Br 2 occurs predominantly via reaction with OH (τ hυ =8300 days, τ OH =143 days). The simulated atmospheric lifetime of CH 2 Br 2 is 140 days, longer than the 100 days calculated in Kerkweg et al (2008). Our simulated seasonal cycle of CHBr 3 at Hawaii (maximum in winter ∼0.7 pptv and minimum in summer ∼0.3 pptv) matches well with observations from Atlas and Ridley (1996).…”

Section: Bromine Chemistry In the Geos Ccmsupporting

confidence: 75%

“…The global emission of 104 Gg Br yr −1 used in simulation B was deduced in Warwick et al (2006) by matching the background atmospheric concentrations. Kerkweg et al (2008) also found that their simulated CH 2 Br 2 with the global emission estimate suggested by Warwick et al (2006) is too high compared against the vertical profiles obtained during PEM-Tropics A and B. The difference is most likely due to differences in the OH fields in individual models.…”

Section: Impact Of Emissionmentioning

confidence: 92%

“…Earlier studies by Dvortsov et al (1999) and Nielsen and Douglass (2001) calculated a maximum of 1.8 pptv and 1.1 pptv Br y , respectively, in the stratosphere from bromoform (CHBr 3 ). More recent modeling studies by Kerkweg et al (2008), Gettelman et al (2009), Aschmann et al (2009) and Hossaini et al (2010) suggested that CHBr 3 and CH 2 Br 2 contribute significant amounts of reactive bromine to the lower stratosphere, with the calculated contribution varying between ∼2-3 pptv among individual studies. One exception is the modeling study by Warwick et al (2006) which presented a detailed emissionbased modeling analysis of all five major VSL oceanic bromocarbons, including CHBr 3 , dibromomethane (CH 2 Br 2 ), bromodichloromethane (CHBrCl 2 ), dibromochloromethane (CHBr 2 Cl), and bromochloromethane (CH 2 BrCl).…”

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confidence: 99%

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Finding the missing stratospheric Bry: a global modeling study of CHBr3 and CH2Br2

et al. 2010

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Abstract. Recent in situ and satellite measurements suggest a contribution of ∼5 pptv to stratospheric inorganic bromine from short-lived bromocarbons. We conduct a modeling study of the two most important short-lived bromocarbons, bromoform (CHBr 3 ) and dibromomethane (CH 2 Br 2 ), with the Goddard Earth Observing System Chemistry Climate Model (GEOS CCM) to account for this missing stratospheric bromine. We derive a "top-down" emission estimate of CHBr 3 and CH 2 Br 2 using airborne measurements in the Pacific and North American troposphere and lower stratosphere obtained during previous NASA aircraft campaigns. Our emission estimate suggests that to reproduce the observed concentrations in the free troposphere, a global oceanic emission of 425 Gg Br yr −1 for CHBr 3 and 57 Gg Br yr −1 for CH 2 Br 2 is needed, with 60% of emissions from open ocean and 40% from coastal regions. Although our simple emission scheme assumes no seasonal variations, the model reproduces the observed seasonal variations of the short-lived bromocarbons with high concentrations in winter and low concentrations in summer. This indicates that the seasonality of short-lived bromocarbons is largely due to seasonality in their chemical loss and transport. The inclusion Correspondence to: Q. Liang (qing.liang@nasa.gov) of CHBr 3 and CH 2 Br 2 contributes ∼5 pptv bromine throughout the stratosphere. Both the source gases and inorganic bromine produced from source gas degradation (Br VSLS y ) in the troposphere are transported into the stratosphere, and are equally important. Inorganic bromine accounts for half (2.5 pptv) of the bromine from the inclusion of CHBr 3 and CH 2 Br 2 near the tropical tropopause and its contribution rapidly increases to ∼100% as altitude increases. More than 85% of the wet scavenging of Br VSLS y occurs in large-scale precipitation below 500 hPa. Our sensitivity study with wet scavenging in convective updrafts switched off suggests that Br VSLS y in the stratosphere is not sensitive to convection. Convective scavenging only accounts for ∼0.2 pptv (4%) difference in inorganic bromine delivered to the stratosphere.

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Section: Impact Of Emissionsupporting

confidence: 82%

Section: Bromine Chemistry In the Geos Ccmsupporting

confidence: 75%

Section: Impact Of Emissionmentioning

confidence: 92%

mentioning

confidence: 99%

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Finding the missing stratospheric Bry: a global modeling study of CHBr3 and CH2Br2

et al. 2010

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“…Bromine radical chemistry in the troposphere is initiated by the production of gas-phase inorganic bromine (Br y ) from photolysis and oxidation of short-lived bromocarbons and from debromination of sea-salt aerosol (Yang et al, 2005;Kerkweg et al, 2008). Br y cycles between BrO x and nonradical reservoirs (principally HBr, HOBr, BrNO 3 , BrNO 2 , Br 2 ) and is eventually lost by deposition.…”

Section: J P Parrella Et Al: Tropospheric Bromine Chemistrymentioning

confidence: 99%

Tropospheric bromine chemistry: implications for present and pre-industrial ozone and mercury

et al. 2012

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Abstract. We present a new model for the global tropospheric chemistry of inorganic bromine (Br y ) coupled to oxidant-aerosol chemistry in the GEOS-Chem chemical transport model (CTM). Sources of tropospheric Br y include debromination of sea-salt aerosol, photolysis and oxidation of short-lived bromocarbons, and transport from the stratosphere. Comparison to a GOME-2 satellite climatology of tropospheric BrO columns shows that the model can reproduce the observed increase of BrO with latitude, the northern mid-latitudes maximum in winter, and the Arctic maximum in spring. This successful simulation is contingent on the HOBr + HBr reaction taking place in aqueous aerosols and ice clouds. Bromine chemistry in the model decreases tropospheric ozone mixing ratios by < 1-8 nmol mol −1 (6.5 % globally), with the largest effects in the northern extratropics in spring. The global mean tropospheric OH concentration decreases by 4 %. Inclusion of bromine chemistry improves the ability of global models (GEOS-Chem and p-TOMCAT) to simulate observed 19th-century ozone and its seasonality. Bromine effects on tropospheric ozone are comparable in the present-day and pre-industrial atmospheres so that estimates of anthropogenic radiative forcing are minimally affected. Br atom concentrations are 40 % higher in the pre-industrial atmosphere due to lower ozone, which would decrease by a factor of 2 the atmospheric lifetime of elemental mercury against oxidation by Br. This suggests that historical anthropogenic mercury emissions may have mostly deposited to northern mid-latitudes, enriching the corresponding surface reservoirs. The persistent rise in background surface ozone at northern mid-latitudes during the past decades could possibly contribute to the observations of elevated mercury in subsurface waters of the North Atlantic.

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Simulating the impact of emissions of brominated very short lived substances on past stratospheric ozone trends

Sinnhuber

Meul

2015

Geophysical Research Letters

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Bromine from very short lived substances (VSLS), primarily from natural oceanic sources, contributes substantially to the stratospheric bromine loading. This source of stratospheric bromine has so far been ignored in most chemistry climate model calculations of stratospheric ozone trends. Here we present a transient simulation with the chemistry climate model EMAC for the period 1960–2005 including emissions of the five brominated VSLS CHBr3, CH2Br2, CH2BrCl, CHBrCl2, and CHBr2Cl. The emissions lead to a realistic stratospheric bromine loading of about 20 pptv for present‐day conditions. Comparison with a standard model simulation without VSLS shows large differences in modeled ozone in the extratropical lowermost stratosphere and in the troposphere. Differences in ozone maximize in the Antarctic Ozone Hole, resulting in more than 20% less ozone when VSLS are included. Even though the emissions of VSLS are assumed to be constant in time, the model simulation with VSLS included shows a much larger ozone decrease in the lowermost stratosphere during the 1979–1995 period and a faster ozone increase during 1996–2005, in better agreement with observed ozone trends than the standard simulation without VSLS emissions.

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Consistent simulation of bromine chemistry from the marine boundary layer to the stratosphere – Part 2: Bromocarbons

Cited by 54 publications

References 67 publications

Finding the missing stratospheric Br<sub>y</sub>: a global modeling study of CHBr<sub>3</sub> and CH<sub>2</sub>Br<sub>2</sub>

Finding the missing stratospheric Br<sub>y</sub>: a global modeling study of CHBr<sub>3</sub> and CH<sub>2</sub>Br<sub>2</sub>

Tropospheric bromine chemistry: implications for present and pre-industrial ozone and mercury

Simulating the impact of emissions of brominated very short lived substances on past stratospheric ozone trends

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Consistent simulation of bromine chemistry from the marine boundary layer to the stratosphere – Part 2: Bromocarbons

Cited by 54 publications

References 67 publications

Finding the missing stratospheric Br&lt;sub&gt;y&lt;/sub&gt;: a global modeling study of CHBr&lt;sub&gt;3&lt;/sub&gt; and CH&lt;sub&gt;2&lt;/sub&gt;Br&lt;sub&gt;2&lt;/sub&gt;

Finding the missing stratospheric Br&lt;sub&gt;y&lt;/sub&gt;: a global modeling study of CHBr&lt;sub&gt;3&lt;/sub&gt; and CH&lt;sub&gt;2&lt;/sub&gt;Br&lt;sub&gt;2&lt;/sub&gt;

Tropospheric bromine chemistry: implications for present and pre-industrial ozone and mercury

Simulating the impact of emissions of brominated very short lived substances on past stratospheric ozone trends

Contact Info

Product

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Finding the missing stratospheric Br<sub>y</sub>: a global modeling study of CHBr<sub>3</sub> and CH<sub>2</sub>Br<sub>2</sub>

Finding the missing stratospheric Br<sub>y</sub>: a global modeling study of CHBr<sub>3</sub> and CH<sub>2</sub>Br<sub>2</sub>