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Atmos. Chem. Phys., 12, 1353-1365, 2012
www.atmos-chem-phys.net/12/1353/2012/ doi:10.5194/acp-12-1353-2012 © Author(s) 2012. This work is distributed under the Creative Commons Attribution 3.0 License. |
ClOOCl photolysis at high solar zenith angles: analysis of the RECONCILE self-match flight
1Institut für Energie- und Klimaforschung: Stratosphäre (IEK-7), Forschungszentrum Jülich GmbH, Germany
2Alfred-Wegener-Institut für Polar- und Meeresforschung, Potsdam, Germany
3Fachbereich C – Abteilung Physik, Bergische Universität Wuppertal, Germany
4Institut für Physik der Atmosphäre, Johannes Gutenberg Universität Mainz, Germany
5Partikelchemie Abteilung, Max-Planck-Institut für Chemie, Mainz, Germany
6Jülich Supercomputing Centre (JSC), Forschungszentrum Jülich GmbH, Germany
7CSEM Centre Suisse d'Electronique et de Microtechnique SA, Neuchâtel, Switzerland
8Meteorologisches Institut, Ludwig-Maximilians-Universität, München, Germany
Abstract. The photolysis rate constant of dichlorine peroxide (ClOOCl, ClO dimer) JClOOCl is a critical parameter in catalytic cycles destroying ozone (O3) 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 JClOOCl. Previous investigations of the consistency of published JClOOCl 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 JClOOCl over the ClOOCl formation rate constant krec. Here, we constrain the atmospherically effective JClOOCl independent of krec, 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 JClOOCl 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).
Citation: Sumińska-Ebersoldt, O., Lehmann, R., Wegner, T., Grooß, J.-U., Hösen, E., Weigel, R., Frey, W., Griessbach, S., Mitev, V., Emde, C., Volk, C. M., Borrmann, S., Rex, M., Stroh, F., and von Hobe, M.: ClOOCl photolysis at high solar zenith angles: analysis of the RECONCILE self-match flight, Atmos. Chem. Phys., 12, 1353-1365, doi:10.5194/acp-12-1353-2012, 2012.