Stratospheric HBr concentration profile obtained from far‐infrared emission spectroscopy

Nolt, I. G.; Ade, Peter A. R.; Alboni, F.; Carli, B.; Carlotti, M.; Cortesi, Ugo; Epifani, M.; Griffin, Matthew Joseph; Hamilton, Peter A.; Lee, C.; Lepri, G.; Mencaraglia, F.; Murray, Alexander; Park, J. H.; Park, K.; Raspollini, Piera; Ridolfi, Marco; Vanek, M.D.

doi:10.1029/97gl00034

Cited by 34 publications

(25 citation statements)

References 15 publications

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“…The absolute yield y Cl2 of Cl 2 and y Br2 of Br 2 are given by the time integral of the instantaneous yields y Cl2 and y Br2 presented in Eqs. (6) and (7) with a…”

Section: A Clono 2 + Hbr/icementioning

confidence: 99%

“…..) concentration. Bromine monoxide BrO is, in addition to HBr [6], among the most important active bromine compounds which has been observed both in the stratosphere [7,8] as well as in the troposphere [9]. Under certain conditions the measured local tropospheric concentrations of BrO can by far exceed the stratospheric concentrations, both in the Arctic [10] as well as in the midlatitude troposphere [11].…”

Section: Introductionmentioning

confidence: 99%

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The Heterogeneous Kinetics of the Reactions ClONO2 + HX/ice (X = Br, I), BrONO2 + HI/ice and the Reactivity of the Interhalogens BrCl, ICl and IBr with HX/ice (X = Cl, Br, I) in the Temperature Range 180 to 205 K

Allanic¹,

Oppliger²,

Bergh³

et al. 2000

Zeitschrift Für Physikalische Chemie

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The kinetics and mechanism of the title heterogeneous halogen exchange reactions of potential atmospheric importance have been studied under molecular flow conditions in a FEP Teflon-coated Knudsen flow reactor on HX (X ϭ Cl, Br, I) Ϫ doped ice condensed from the vapor phase under conditions of several formal monolayers of HX coverage at approximately 200 K. In addition, the halogen exchange reactions involving the expected primary reaction products BrCl, ICl and IBr of the above mixed anhydrides with HXdoped ice have been studied at 200 K as well. The uptake coefficient γ for the heterogeneous reaction ClONO2 ϩ HBr on ice is 0.56 Ϯ 0.11 and Cl2 and Br2 are formed in yields of 100% and 66 to 80%, respectively, in the range 180 to 200 K. The γ value for the reaction ClONO2 ϩ HI on ice is 0.30Ϯ0.02 at 200 K with Cl2 being the main product appearing after an induction time. The primary product ICl is formed at the same time as Cl 2 whereas HOCl appears at a later time under conditions of waning HI supply. The γ value for the reaction BrONO 2 ϩ HI on ice is 0.40Ϯ0.02 at 200 K with Br 2 being the main product observed after a short delay. The primary product IBr is observed without delay, whereas HOBr is observed at a later time once HBr has reacted. The mechanism of the reactions of the interhalogens BrCl, ICl and IBr with HX on ice at 200 K involves the formation of trihalide ions at the ice interface which is consistent with the observed significant negative temperature dependence for the reaction ICl ϩ HBr on ice in the range 180 to 205 K as well as for the reaction BrCl ϩ HBr between 190 and 200 K. The uptake coefficient γ for each of the interhalogens increases from ice to HI-doped ice in the order of increasing molecular weight of HX with the exception of ICl, whose γ attains a limiting value of γ ϭ 0.32Ϯ0.05. A halogen exchange reaction on ice has been observed in cases where the most stable hydrohalic acid could be formed: HCl Ͼ HBr Ͼ HI. A propensity for the formation of the homonuclear halogen molecule in the reactions of halogen nitrates with HX-doped ice has been explained by the occurrence of fast secondary reactions of the primary interhalogen product at the HX/ice interface.

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“…The absolute yield y Cl2 of Cl 2 and y Br2 of Br 2 are given by the time integral of the instantaneous yields y Cl2 and y Br2 presented in Eqs. (6) and (7) with a…”

Section: A Clono 2 + Hbr/icementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The Heterogeneous Kinetics of the Reactions ClONO2 + HX/ice (X = Br, I), BrONO2 + HI/ice and the Reactivity of the Interhalogens BrCl, ICl and IBr with HX/ice (X = Cl, Br, I) in the Temperature Range 180 to 205 K

Allanic¹,

Oppliger²,

Bergh³

et al. 2000

Zeitschrift Für Physikalische Chemie

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“…The partitioning between bromine species is still subject to speculation, since only BrO has been routinely observed, while a few measurements of stratospheric HBr and an upper limit of HOBr [ Johnson et al , 1995; Nolt et al , 1997] are available only. The other species, Br, BrONO 2 , and BrCl, have never been observed.…”

Section: Introductionmentioning

confidence: 99%

Climatology of the stratospheric BrO vertical distribution by balloon‐borne UV–visible spectrometry

et al. 2002

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[1] A balloon-borne UV-visible spectrometer, the SAOZ-BrO, has been designed for the measurement of BrO on small and relatively low-cost balloons. It allows the retrieval of the vertical BrO profile with a resolution of 1 km, a precision of 0.5-2 pptv (below 25 km), and a +5/À10% accuracy during the daytime balloon ascent. Fifteen successful flights have been carried out since 1997. Significant BrO amounts were observed at all latitudes and seasons, with a peak concentration altitude varying from 15 km in the winter vortex to 22 km in the tropics. The mixing ratio increases steadily from the tropopause to 25-30 km, depending on the latitude, above which it remains constant up to 30 km. The latitudinal and seasonal changes (maximum at high latitude and in the winter) are largely controlled by the vertical transport of total inorganic bromine and to a smaller extent by photochemistry. Photochemical changes are primarily related to NO 2 abundances. On a constant potential temperature surface, the BrO mixing ratio is the largest in Polar Regions in the winter, where NO 2 is nearly absent. In contrast, BrO is the smallest during the polar day and in the summer at midlatitude. The presence of activated chlorine in the cold vortex has little impact on BrO abundances. Finally, significant amounts were observed in the upper troposphere: (1) in the summer at midlatitude where it was the result of a stratosphere-troposphere exchange (STE) event advecting bromine from the stratosphere and (2) at the tropics where its presence is likely due to the conversion of organic bromine at lower altitude.

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“…The HOBr value (7 pptv) was derived from (HOBr/HBr) = 1.4 on the basis of Johnson et al [1995]. The HBr value (5 pptv) is uncertain and may be somewhat high in the model since measurements by Nolt et al [1997] and Johnson et al [1995] suggest 1–2 pptv and 2–3 pptv HBr in the lower stratosphere, respectively. The model calculated a midday value of (BrO/Bry) = 0.50 on day 10, i.e., [BrO] = 10 pptv, consistent with the studies of Pundt et al [1998] and Harder et al [1998] which suggested a range of 5–15 pptv.…”

Section: Procedures and Modelsmentioning

confidence: 99%

Chemical reaction pathways affecting stratospheric and mesospheric ozone

et al. 2006

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[1] Catalytic cycles and other chemical pathways affecting ozone are normally estimated empirically in atmospheric models. In this work we have automatically quantified such processes by applying a newly developed analysis package called the ''Pathway Analysis Program'' (PAP). It used modeled chemical rates and concentrations as input. These were supplied by the ''Module Efficiently Calculating the Chemistry of the Atmosphere'' MECCA box model, itself initialized by the Free University of Berlin Climate Middle Atmosphere Model with Chemistry. We analyzed equatorial, midlatitude and high-latitude locations over 24-hour periods during spring in both hemispheres. We present results for locations in the lower stratosphere, upper stratosphere and midmesosphere. Oxygen photolysis dominated (>99%) in situ ozone production in the equatorial lower stratosphere, in the upper stratosphere and in the mesosphere. In the lower stratosphere midlatitudes the ''ozone smog cycle'' (already established in the troposphere) rivaled oxygen photolysis as an in situ ozone source in both hemispheres. However, absolute ozone production rates in midlatitudes were rather slow compared with at the equator, typically 16-50 ppt ozone/day. In the equatorial lower stratosphere, five catalytic sinks were important (each contributing at least 5% to chemical ozone loss): a HOx cycle, a HOBr cycle and its HOCl analog, a water-HOx cycle and a mixed chlorine-bromine cycle. Important in midlatitudes were the HOx cycle, a NOx cycle, the HOBr cycle and the mixed chlorine-bromine cycle. In lowerstratosphere high latitudes, the chlorine dimer cycle and the mixed chlorine-bromine cycle dominated in both hemispheres. A variant on the latter, involving BrCl formation, also featured. In the upper stratosphere high latitudes (where strong negative ozone trends are observed), a nitrogen cycle, a chlorine cycle, and a mixed chlorinenitrogen cycle were found. In the mesosphere, three closely related HOx cycles dominated ozone loss.

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Stratospheric HBr concentration profile obtained from far‐infrared emission spectroscopy

Cited by 34 publications

References 15 publications

The Heterogeneous Kinetics of the Reactions ClONO2 + HX/ice (X = Br, I), BrONO2 + HI/ice and the Reactivity of the Interhalogens BrCl, ICl and IBr with HX/ice (X = Cl, Br, I) in the Temperature Range 180 to 205 K

The Heterogeneous Kinetics of the Reactions ClONO2 + HX/ice (X = Br, I), BrONO2 + HI/ice and the Reactivity of the Interhalogens BrCl, ICl and IBr with HX/ice (X = Cl, Br, I) in the Temperature Range 180 to 205 K

Climatology of the stratospheric BrO vertical distribution by balloon‐borne UV–visible spectrometry

Chemical reaction pathways affecting stratospheric and mesospheric ozone

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