A re-evaluation of the ClO/Cl&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;O&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; equilibrium constant based on stratospheric in-situ observations

Hobe, Marc von; Grooß, Jens‐Uwe; Müller, Rolf; Hrechanyy, Serhiy; Winkler, Ulrike; Stroh, F.

doi:10.5194/acp-5-693-2005

Cited by 56 publications

(74 citation statements)

References 31 publications

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“…And because spectrum peak cross section are not determined independently in that study, chances are that the peak cross sections would also be erroneous. Using the different spectral shape as an argument against scaling to some other absolute cross sections, we do note that the von Hobe et al (2009) spectrum scaled to Lien et al (2009) also does not fully agree with the cross sections at longer wavelength proposed by the same group from Taiwan Jin et al, 2010). However, the molecular beam cross section measurements represent independent experiments at five different wavelengths, and they represent photolysis rather than absorption cross sections.…”

Section: O Sumińska-ebersoldt Et Al: Cloocl Photolysis At High Solamentioning

confidence: 94%

“…The two spectra have slightly different shapes but yield similar atmospheric J ClOOCl values. The results presented by Burkholder et al (1990) generally produced the best agreement in a number of studies comparing modelled and observed ClO x partitioning (Stimpfle et al, 2004;von Hobe et al, 2007;Schofield et al, 2008;Kremser et al, 2011) as well as ozone loss (Santee et al, 2003;Chipperfield et al, 2005;Frieler et al, 2006;Tripathi et al, 2006;von Hobe et al, 2007). Results of Papanastasiou et al (2009) are recommended in JPL 2011 (Sander et al, 2011).…”

Section: Investigated σ Clooclmentioning

confidence: 96%

“…It seems unreasonable to scale a relative absorption spectrum to an absolute cross section associated with a different spectral shape, because then the two studies are contradictory, and it makes no sense to scale one to the other. For example, the shapes of the von Hobe et al (2009) Hobe et al (2009) were right, then the spectral shape was not measured correctly by Papanastasiou et al (2009). And because spectrum peak cross section are not determined independently in that study, chances are that the peak cross sections would also be erroneous.…”

Section: O Sumińska-ebersoldt Et Al: Cloocl Photolysis At High Solamentioning

confidence: 99%

“…JPL 2011 k rec was chosen as the current recommendation to the scientific community, whereas k rec published by Nickolaisen et al (1994) due to its good agreement with both atmospheric observations and unimolecular theory as shown by von Hobe et al (2007).…”

Section: Chemistry Simulations Along Match Trajectoriesmentioning

confidence: 99%

“…For the entire wavelength range relevant for ClOOCl photolysis in the stratosphere (λ > 310 nm), absorption cross sections (Cox and Hayman, 1988;DeMore and Tschuikow-Roux, 1990;Burkholder et al, 1990;Bloss et al, 2001;Papanastasiou et al, 2009) or relative absorption spectra (Huder and DeMore, 1995;von Hobe et al, 2009;Pope et al, 2007) have been measured by UV/Vis absorption spectroscopy.…”

Section: O Sumińska-ebersoldt Et Al: Cloocl Photolysis At High Solamentioning

confidence: 99%

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ClOOCl photolysis at high solar zenith angles: analysis of the RECONCILE self-match flight

Suminska-Ebersoldt¹,

Lehmann

Wegner³

et al. 2012

Atmos. Chem. Phys.

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Abstract. The photolysis rate constant of dichlorine peroxide (ClOOCl, ClO dimer) J ClOOCl is a critical parameter in catalytic cycles destroying ozone (O 3 ) in the polar stratosphere. In the atmospherically relevant wavelength region (λ > 310 nm), significant discrepancies between laboratory measurements of ClOOCl absorption cross sections and spectra cause a large uncertainty in J ClOOCl . Previous investigations of the consistency of published J ClOOCl with atmospheric observations of chlorine monoxide (ClO) and ClOOCl have focused on the photochemical equilibrium between ClOOCl formation and photolysis, and thus could only constrain the ratio of J ClOOCl over the ClOOCl formation rate constant k rec . Here, we constrain the atmospherically effective J ClOOCl independent of k rec , using ClO measured in the same air masses before and directly after sunrise during an aircraft flight that was part of the RECONCILE field campaign in the winter 2010 from Kiruna, Sweden. Over sunrise, when the ClO/ClOOCl system comes out of thermal equilibrium and the influence of the ClO recombination reaction is negligible, the increase in ClO concentrations is significantly faster than expected from J ClOOCl based on the absorption spectrum proposed by Pope et al. (2007), but does not warrant cross sections larger than recently published values by Papanastasiou et al. (2009). In particular, the existence of a significant ClOOCl absorption band longwards of 420 nm is not supported by our observations. The observed night-time ClO would not be consistent with a ClO/ClOOCl thermal equilibrium constant significantly higher than the one proposed by Plenge et al. (2005).

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Section: O Sumińska-ebersoldt Et Al: Cloocl Photolysis At High Solamentioning

confidence: 94%

Section: Investigated σ Clooclmentioning

confidence: 96%

Section: O Sumińska-ebersoldt Et Al: Cloocl Photolysis At High Solamentioning

confidence: 99%

Section: Chemistry Simulations Along Match Trajectoriesmentioning

confidence: 99%

Section: O Sumińska-ebersoldt Et Al: Cloocl Photolysis At High Solamentioning

confidence: 99%

See 3 more Smart Citations

ClOOCl photolysis at high solar zenith angles: analysis of the RECONCILE self-match flight

Suminska-Ebersoldt¹,

Lehmann

Wegner³

et al. 2012

Atmos. Chem. Phys.

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Constraints for the photolysis rate and the equilibrium constant of ClO‐dimer from airborne and balloon‐borne measurements of chlorine compounds

et al. 2014

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We analyze measurements of ClO across the terminator taken by the Airborne Submillimeter Radiometer (ASUR) in the activated vortices of the Arctic winters of 1995/1996, 1996/1997, and 1999/2000 to evaluate the plausibility of various determinations of the ClO‐dimer photolysis cross section and the rate constant controlling the thermal equilibrium between ClO‐dimer and ClO. We use measured ClO during sunlit conditions to estimate total active chlorine (ClOx). As the measurements suggest nearly full chlorine activation in winter 1999/2000, we compare ClOx estimates based on various photolysis frequencies of ClO‐dimer with total available inorganic chlorine (Cly), estimated from an N2O‐Cly correlation established by a balloon‐borne MkIV interferometer measurement. Only ClO‐dimer cross sections leading to the fastest photolysis frequencies in the literature (including the latest evaluation by the Jet Propulsion Laboratory) give ClOx mixing ratios that overlap with the estimated range of available Cly. Slower photolysis rates lead to ClOx values that are higher than available Cly. We use the ClOx calculated from sunlit ClO measurements to estimate ClO in darkness based on different equilibrium constants, and compare it with ASUR ClO measurements before sunrise at high solar zenith angles. Calculations with equilibrium constants published in recent evaluations of the Jet Propulsion Laboratory give good agreement with observed ClO mixing ratios. Equilibrium constants leading to a higher ClO/ClOx ratio in darkness yield ClO values that tend to exceed observed abundances. Perturbing the rates for the ClO + BrO reaction in a manner that increases OClO formation and decreases BrCl formation leads to lower ClO values calculated for twilight conditions after sunset, resulting in better agreement with ASUR measurements.

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The kinetics of the ClOOCl catalytic cycle

2016

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We use simultaneous in situ observations of [ClO] and [ClOOCl] obtained in the Arctic polar vortex to evaluate the kinetics of the ClOOCl catalytic cycle. Available laboratory measurements of the ClOOCl absorption cross sections, the ClO + ClO + M reaction rate constant, and the ClO/ClOOCl equilibrium constant are considered, along with compendium evaluations of these kinetic parameters. We show that the most recent (year 2015) recommendations for the kinetics that govern the partitioning of ClO and ClOOCl put forth by the Jet Propulsion Laboratory (JPL) panel are in extremely good agreement with the atmospheric observations of [ClO] and [ClOOCl]. Hence, we suggest that studies of polar ozone loss adopt these most recent recommendations. The most important difference with respect to calculations that rely on older recommendations is the temperature at which loss of O3 by the ClOOCl catalytic cycle terminates. The latest JPL recommendation for the equilibrium constant suggests that ClOOCl is less stable than previously assumed, resulting in an approximate 2°C downward shift in the termination temperature of polar ozone loss due to the ClOOCl catalytic cycle. Remaining uncertainties in our knowledge of the kinetics that govern the partitioning of ClO and ClOOCl within the activated vortex, and hence the efficiency of O3 loss by the ClOOCl cycle, will be best addressed by future laboratory determinations of the absolute cross section of ClOOCl at the peak (i.e., close to a wavelength of 245 nm) as well as reduced uncertainty in the rate constant of the ClO + ClO + M reaction.

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A re-evaluation of the ClO/Cl<sub>2</sub>O<sub>2</sub> equilibrium constant based on stratospheric in-situ observations

Cited by 56 publications

References 31 publications

ClOOCl photolysis at high solar zenith angles: analysis of the RECONCILE self-match flight

ClOOCl photolysis at high solar zenith angles: analysis of the RECONCILE self-match flight

Constraints for the photolysis rate and the equilibrium constant of ClO‐dimer from airborne and balloon‐borne measurements of chlorine compounds

The kinetics of the ClOOCl catalytic cycle

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