Estimating the contribution of bromoform to stratospheric bromine and its relation to dehydration in the tropical tropopause layer

Sinnhuber, Björn‐Martin; Folkins, Ian

doi:10.5194/acp-6-4755-2006

Cited by 58 publications

(79 citation statements)

References 25 publications

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“…For example, as the air masses travel from West to East, heterogeneous recycling reactions could put more Br back into the troposphere than washout is removing. Previous studies have pointed out that rapid uplift of air masses, due to convection events, as well as the colder temperatures within the TTL, can considerably enhance the efficiency of heterogeneous reactions relative to complete washout or ice removal (3,4,22,23). However, the impact of heterogeneous reactions depends on several factors, including the microphysical environment and the partitioning of the inorganic bromine species.…”

Section: Significancementioning

confidence: 99%

Airborne measurements of organic bromine compounds in the Pacific tropical tropopause layer

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Saiz‐Lopez

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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Very short-lived brominated substances (VSLBr) are an important source of stratospheric bromine, an effective ozone destruction catalyst. However, the accurate estimation of the organic and inorganic partitioning of bromine and the input to the stratosphere remains uncertain. Here, we report near-tropopause measurements of organic brominated substances found over the tropical Pacific during the NASA Airborne Tropical Tropopause Experiment campaigns. We combine aircraft observations and a chemistry−climate model to quantify the total bromine loading injected to the stratosphere. Surprisingly, despite differences in vertical transport between the Eastern and Western Pacific, VSLBr (organic + inorganic) contribute approximately similar amounts of bromine [∼6 (4−9) parts per thousand] to the stratospheric input at the tropical tropopause. These levels of bromine cause substantial ozone depletion in the lower stratosphere, and any increases in future abundances (e.g., as a result of aquaculture) will lead to larger depletions.

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Section: Significancementioning

confidence: 99%

Airborne measurements of organic bromine compounds in the Pacific tropical tropopause layer

Navarro

Atlas

Saiz‐Lopez

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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“…This comparison and the comparison with the available data from other studies (e.g. Schauffler et al, 1999;Sinnhuber and Folkins, 2006) indicate that the variabilities of the VSLS concentrations are relatively high in the TTL, due to variations of the source emissions and of the related transport processes into the TTL. Nevertheless, in the specific case of the 2005 Teresina sample, we expect a considerable decay of the VSLS in the BONBON canisters during storage of 8 months between sampling and measurements.…”

Section: Comparison and Discussionmentioning

confidence: 92%

“…Additional removal can be caused by falling ice particles, which form during the dehydration of rising air parcels up to the coldpoint tropopause (e.g. Sinnhuber and Folkins, 2006). On the other hand, inorganic bromine already present near the LZRH could compensate for the loss of Br y produced and Table 8.…”

Section: Comparison and Discussionmentioning

confidence: 99%

Short-lived brominated hydrocarbons – observations in the source regions and the tropical tropopause layer

et al. 2012

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Abstract. We conducted measurements of the five important short-lived organic bromine species in the marine boundary layer (MBL). Measurements were made in the Northern Hemisphere mid-latitudes (Sylt Island, North Sea) in June 2009 and in the tropical Western Pacific during the TransBrom ship campaign in October 2009. For the one-week time series on Sylt Island, mean mixing ratios of CHBr 3 , CH 2 Br 2 , CHBr 2 Cl and CH 2 BrCl were 2.0, 1.1, 0.2, 0.1 ppt, respectively. We found maxima of 5.8 and 1.6 ppt for the two main components CHBr 3 and CH 2 Br 2 . Along the cruise track in the Western Pacific (between 41 • N and 13 • S) we measured mean mixing ratios of 0.9, 0.9, 0.2, 0.1 and 0.1 ppt for CHBr 3 , CH 2 Br 2 , CHBrCl 2 , CHBr 2 Cl and CH 2 BrCl. Air samples with coastal influence showed considerably higher mixing ratios than the samples with open ocean origin. Correlation analyses of the two data sets yielded strong linear relationships between the mixing ratios of four of the five species (except for CH 2 BrCl). Using a combined data set from the two campaigns and a comparison with the results from two former studies, rough estimates of the molar emission ratios between the correlated substances were: 9/1/0.35/0.35 for CHBr 3 /CH 2 Br 2 /CHBrCl 2 /CHBr 2 Cl. Additional measurements were made in the tropical tropopause layer (TTL) above Teresina (Brazil, 5 • S) in June 2008, using balloon-borne cryogenic whole air sampling technique. Near the level of zero clear-sky net radiative heating (LZRH) at 14.8 km about 2.25 ppt organic bromine was bound to the five short-lived species, making up 13 % of total organic bromine (17.82 ppt). CH 2 Br 2 (1.45 ppt) and CHBr 3 (0.56 ppt) accounted for 90 % of the budget of short-lived compounds in that region. Near the tropopause (at 17.5 km) organic bromine from these substances was reduced to 1.35 ppt, with 1.07 and 0.12 ppt attributed to CH 2 Br 2 and CHBr 3 , respectively.

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“…The fact that GEOS CCM captures well the observed profiles during Pre-AVE, AVE, and TC4 implies that the overestimate during STRAT may not be due to excessive convective transport. The difference between the CHBr 3 during STRAT and that during Pre-AVE has been previous noted in Sinnhuber and Folkins (2006) and was suggested to reflect the differences in the activity of deep convection between the missions. We have examined in detail the location of measurements and how the canister samples were processed during STRAT.…”

Section: Chbrmentioning

confidence: 99%

“…Convective lofting is suggested to be the most important pathway of air entering the stratosphere (e.g. Sinnhuber and Folkins, 2006;Fueglistaler et al, 2009). Air masses entering the stratosphere must be dehydrated and soluble substances, e.g.…”

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confidence: 99%

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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Estimating the contribution of bromoform to stratospheric bromine and its relation to dehydration in the tropical tropopause layer

Cited by 58 publications

References 25 publications

Airborne measurements of organic bromine compounds in the Pacific tropical tropopause layer

Airborne measurements of organic bromine compounds in the Pacific tropical tropopause layer

Short-lived brominated hydrocarbons – observations in the source regions and the tropical tropopause layer

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>

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Estimating the contribution of bromoform to stratospheric bromine and its relation to dehydration in the tropical tropopause layer

Cited by 58 publications

References 25 publications

Airborne measurements of organic bromine compounds in the Pacific tropical tropopause layer

Airborne measurements of organic bromine compounds in the Pacific tropical tropopause layer

Short-lived brominated hydrocarbons – observations in the source regions and the tropical tropopause layer

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;

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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>