ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-11-689-2011 Evaluation of stratospheric chlorine chemistry for the Arctic spring 2005 using modelled and measured OClO column densities Oetjen H. 1 2 Wittrock F. 1 Richter A. 1 Chipperfield M. P. 3 Medeke T. 1 Sheode N. 1 Sinnhuber B.-M. 1 Sinnhuber M. 1 Burrows J. P. 1 University of Bremen, Institute of Environmental Physics, Germany University of Leeds, School of Chemistry Leeds, UK University of Leeds, School of Earth and Environment, Leeds, UK 24 01 2011 11 2 689 703 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.atmos-chem-phys.net/11/689/2011/acp-11-689-2011.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/11/689/2011/acp-11-689-2011.pdf

Chlorine dioxide, OClO, column amounts retrieved from measurements of the SCIAMACHY satellite instrument are presented and validated by comparison with simultaneous ground-based DOAS observations. In addition, the measurements are compared to model calculations taking into account the photochemical change along the light path. <br><br> Although OClO does not participate directly in the destruction of ozone, its accurate measurement as well as modelling is crucial to understand the highly perturbed chlorine chemistry in the polar vortices. SCIAMACHY OClO slant columns retrieved during spring 2005 have been quantitatively validated by comparison with slant columns retrieved from measurements made in Ny-Ålesund (79° N, 12° E) and Summit (73° N, 38° W) as well qualitatively for Bremen (53° N, 9° E). Fair to good agreement is found depending on location as well as time of year. <br><br> OClO slant column densities modelled with a set of stacked box models and considering the light path through the atmosphere are also included in this comparison. The model predictions differ significantly from the measured quantities. OClO amounts are underestimated for conditions of strong chlorine activation and at large solar zenith angles. Sensitivity studies for several parameters in the stacked box model have been performed and it is inferred that using the chemistry known to date, the observed OClO cannot be adequately reproduced within the range of uncertainties given for the various model parameters.

 References Aliwell, S. R., Jones, R. L., and Fish, D. J.: Mid-latitude observations of the seasonal variation of BrO.1, Zenith-sky measurements, Geophys. Res. Lett., 24, 1195–1198, 1997. Aliwell, S. R., Van Roozendael, M., Johnston, P. V., Richter, A., Wagner, T., Arlander, D. W., Burrows, J. P., Fish, D. J., Jones, R. L., Tørnkvist, K. K., Lambert, J. C., Pfeilsticker, K., and Pundt, I.: Analysis for BrO in zenith-sky spectra: An intercomparison exercise for analysis improvement, J. Geophys. Res.-Atmos., 107(20), 4199, doi:10.1029/2001jd000329, 2002. Atkinson, R., Baulch, D. L., Cox, R. A., Hampson, R. F., Kerr, J. A., Rossi, M. J., and Troe, J.: Evaluated kinetic and photochemical data for atmospheric chemistry: Supplement VIII, halogen species – IUPAC Subcommittee on Gas Kinetic Data Evaluation for Atmospheric Chemistry, J. Phys. Chem. Ref. Data, 29, 167–266, 2000. Avallone, L. M. and Toohey, D. W.: Tests of halogen photochemistry using in situ measurements of CIO and BrO in the lower polar stratosphere, J. Geophys. Res.-Atmos., 106, 10411–10421, 2001. Barret, B., Ricaud, P., Santee, M. L., Attie, J. L., Urban, J., Le Flochmoen, E., Berthet, G., Murtagh, D., Eriksson, P., Jones, A., de la Noe, J., Dupuy, E., Froidevaux, L., Livesey, N. J., Waters, J. W., and Filipiak, M. J.: Intercomparisons of trace gases profiles from the Odin/SMR and Aura/MLS limb sounders, J. Geophys. Res.-Atmos., 111(11), D21302, doi:10.1029/2006jd007305, 2006. Basco, N. and Hunt, J. E.: Mutual Combination of ClO Radicals, Int. J. Chem. Kinet., 11, 649–664, 1979. Berthet, G., Ricaud, P., Lefevre, F., Le Flochmoen, E., Urban, J., Barret, B., Lautie, N., Dupuy, E., De la Noe, J., and Murtagh, D.: Nighttime chlorine monoxide observations by the Odin satellite and implications for the ClO/Cl<sub>2</sub>O<sub>2</sub> equilibrium, Geophys. Res. Lett., 32(5), L11812, doi:10.1029/2005gl022649, 2005. Bloss, W. J., Nickolaisen, S. L., Salawitch, R. J., Friedl, R. R., and Sander, S. P.: Kinetics of the ClO self-reaction and 210 nm absorption cross section of the ClO dimer, J. Phys. Chem. A, 105, 11226–11239, 2001. Boakes, G., Mok, W. H. H., and Rowley, D. M.: Kinetic studies of the ClO plus ClO association reaction as a function of temperature and pressure, Phys. Chem. Chem. Phys., 7, 4102–4113, 2005. Bovensmann, H., Burrows, J. P., Buchwitz, M., Frerick, J., Noel, S., Rozanov, V. V., Chance, K. V., and Goede, A. P. H.: SCIAMACHY: Mission objectives and measurement modes, J. Atmos. Sci., 56, 127–150, 1999. Bröske, R. and Zabel, F.: Thermal decomposition of ClOOCl, J. Phys. Chem. A, 110, 3280–3288, 2006. Brune, W. H. and Anderson, J. G.: In situ observations of midlatitude stratospheric ClO and BrO, Geophys. Res. Lett., 13, 1391–1394, 1986. Brune, W. H., Anderson, J. G., Toohey, D. W., Fahey, D. W., Kawa, S. R., Jones, R. L., McKenna, D. S., and Poole, L. R.: The potential for ozone depletion in the Arctic polar stratosphere, Science, 252, 1260–1266, 1991. Burkholder, J. B., Orlando, J. J., and Howard, C. J.: Ultraviolet-Absorption Cross-Section of Cl<sub>2</sub>O<sub>2</sub> between 210 and 410 nm, J. Phys. Chem., 94, 687–695, 1990. Burrows, J. P., Holzle, E., Goede, A. P. H., Visser, H., and Fricke, W.: SCIAMACHY – Scanning Imaging Absorption Spectrometer for Atmospheric Chartography, Acta Astronaut., 35, 445–451, 1995. Burrows, J. P., Weber, M., Buchwitz, M., Rozanov, V., Ladstatter-Weissenmayer, A., Richter, A., DeBeek, R., Hoogen, R., Bramstedt, K., Eichmann, K. U., and Eisinger, M.: The global ozone monitoring experiment (GOME): Mission concept and first scientific results, J. Atmos. Sci., 56, 151–175, 1999. Butz, A., Bösch, H., Camy-Peyret, C., Dorf, M., Engel, A., Payan, S., and Pfeilsticker, K.: Observational constraints on the kinetics of the ClO-BrO and ClO-ClO ozone loss cycles in the Arctic winter stratosphere, Geophys. Res. Lett., 34(5), L05801, doi:10.1029/2006gl028718, 2007. Canty, T., Riviere, E. D., Salawitch, R. J., Berthet, G., Renard, J. B., Pfeilsticker, K., Dorf, M., Butz, A., Bosch, H., Stimpfle, R. M., Wilmouth, D. M., Richard, E. C., Fahey, D. W., Popp, P. J., Schoeberl, M. R., Lait, L. R., and Bui, T. P.: Nighttime OCIO in the winter Arctic vortex, J. Geophys. Res.-Atmos., 110, 1–13, 2005. Chen, H. Y., Lien, C. Y., Lin, W. Y., Lee, Y. T., and Lin, J. J.: UV Absorption Cross Sections of ClOOCl Are Consistent with Ozone Degradation Models, Science, 324, 781–784, doi:10.1126/science.1171305, 2009. Chipperfield, M. P.: Multiannual simulations with a three-dimensional chemical transport model, J. Geophys. Res.-Atmos., 104, 1781-1805, 1999. Chubachi, S.: Preliminary result of ozone observations at Syowa station from February 1982 to January 1983, Mem. Natl. Inst. Polar Res., 34, 13–19, 1984. Cox, R. A. and Hayman, G. D.: The Stability and Photochemistry of Dimers of the ClO Radical and Implications for Antarctic Ozone Depletion, Nature, 332, 796–800, 1988. DeMore, W. B. and Tschuikow-Roux, E.: Ultraviolet-Spectrum and Chemical-Reactivity of the ClO Dimer, J. Phys. Chem., 94, 5856–5860, 1990. Farman, J. C., Gardiner, B. G., and Shanklin, J. D.: Large losses of total ozone in Antarctica reveal seasonal ClO<sub>x</sub>/NO<sub>x</sub> interaction, Nature, 315, 207–210, 1985. Feng, W., Chipperfield, M. P., Davies, S., von der Gathen, P., Kyro, E., Volk, C. M., Ulanovsky, A., and Belyaev, G.: Large chemical ozone loss in 2004/2005 Arctic winter/spring, Geophys. Res. Lett., 34(6), L09803, doi:10.1029/2006gl029098, 2007a. Feng, W., Chipperfield, M. P., Dorf, M., Pfeilsticker, K., and Ricaud, P.: Mid-latitude ozone changes: studies with a 3-D CTM forced by ERA-40 analyses, Atmos. Chem. Phys., 7, 2357–2369, doi:10.5194/acp-7-2357-2007, 2007b. Francisco, J. S. and Sander, S. P.: Existence of a chlorine oxide and water (ClO · H<sub>2</sub>O) radical complex, J. Am. Chem. Soc., 117, 9917–9918, 1995. Friedl, R. R. and Sander, S. P.: Kinetics and Product Studies of the Reaction ClO + BrO Using Discharge-Flow Mass-Spectrometry, J. Phys. Chem., 93, 4756–4764, 1989. Frieß, U., Kreher, K., Johnston, P. V., and Platt, U.: Ground-based DOAS measurements of stratospheric trace gases at two Antarctic stations during the 2002 ozone hole period, J. Atmos. Sci., 62, 765–777, 2005. Fussen, D., Vanhellemont, F., Dodion, J., Bingen, C., Mateshvili, N., Daerden, F., Fonteyn, D., Errera, Q., Chabrillat, S., Kyrola, E., Tamminen, J., Sofieva, V., Hauchecorne, A., Dalaudier, F., Bertaux, J. L., Renard, J. B., Fraisse, R., d'Andon, O. F., Barrot, G., Guirlet, M., Mangin, A., Fehr, T., Snoeij, P., and Saavedra, L.: A global OClO stratospheric layer discovered in GOMOS stellar occultation measurements, Geophys. Res. Lett., 33, L13815, doi:10.1029/2006GL026406, 2006. Galvez, O. and Gomez, P. C.: An ab initio study on the structure and energetics of the ClO hydrates, Chem. Phys. Lett., 448, 16–23, doi:10.1016/j.cplett.2007.09.072, 2007. Gil, M., Puentedura, O., Yela, M., Parrondo, C., Jadhav, D. B., and Thorkelsson, B.: OClO, NO<sub>2</sub> and O<sub>3</sub> total column observations over Iceland during the winter 1993/94, Geophys. Res. Lett., 23, 3337–3340, 1996. Heckel, A., Richter, A., Tarsu, T., Wittrock, F., Hak, C., Pundt, I., Junkermann, W., and Burrows, J. P.: MAX-DOAS measurements of formaldehyde in the Po-Valley, Atmos. Chem. Phys., 5, 909–918, doi:10.5194/acp-5-909-2005, 2005. Hendrick, F., Van Roozendael, M., Kylling, A., Petritoli, A., Rozanov, A., Sanghavi, S., Schofield, R., von Friedeburg, C., Wagner, T., Wittrock, F., Fonteyn, D., and De Maziére, M.: Intercomparison exercise between different radiative transfer models used for the interpretation of ground-based zenith-sky and multi-axis DOAS observations, Atmos. Chem. Phys., 6, 93–108, doi:10.5194/acp-6-93-2006, 2006. Hendrick, F., Van Roozendael, M., Chipperfield, M. P., Dorf, M., Goutail, F., Yang, X., Fayt, C., Hermans, C., Pfeilsticker, K., Pommereau, J.-P., Pyle, J. A., Theys, N., and De Maziére, M.: Retrieval of stratospheric and tropospheric BrO profiles and columns using ground-based zenith-sky DOAS observations at Harestua, 60° N, Atmos. Chem. Phys., 7, 4869–4885, doi:10.5194/acp-7-4869-2007, 2007. Hermans, C., Vandaele, A. C., Carleer, M., Fally, S., Colin, R., Jenouvrier, A., Coquart, B., and Merienne, M. F.: Absorption cross-sections of atmospheric constituents: NO<sub>2</sub>, O<sub>2</sub>, and H<sub>2</sub>O, Environ. Sci. Pollut. R. 6, 151–158, 1999. Horowitz, A., Crowley, J. N., and Moortgat, G. K.: Temperature-Dependence of the Product Branching Ratios of the ClO Self-Reaction in Oxygen, J. Phys. Chem., 98, 11924–11930, 1994. Hubinger, S. and Nee, J. B.: Absorption-Spectra of Cl<sub>2</sub>, Br<sub>2</sub> and BrCl between 190 nm and 600 nm, J. Photoch. Photobio. A, 86, 1–7, 1995. Huder, K. J., and DeMore, W. B.: Absorption Cross-Sections of the ClO Dimer, J. Phys. Chem., 99, 3905–3908, 1995. Krecl, P., Haley, C. S., Stegman, J., Brohede, S. M., and Berthet, G.: Retrieving the vertical distribution of stratospheric OClO from Odin/OSIRIS limb-scattered sunlight measurements, Atmos. Chem. Phys., 6, 1879–1894, doi:10.5194/acp-6-1879-2006, 2006. Kreher, K., Keys, J. G., Johnston, P. V., Platt, U., and Liu, X.: Ground-based measurements of OClO and HCl in austral spring 1993 at Arrival Heights, Antarctica, Geophys. Res. Lett., 23, 1545–1548, 1996. Kromminga, H., Orphal, J., Spietz, P., Voigt, S., and Burrows, J. P.: New measurements of OClO absorption cross-sections in the 325-435 nm region and their temperature dependence between 213 and 293 K, J. Photoch. Photobio. A, 157, 149–160, 2003. Kühl, S.: Quantifying Stratospheric Chlorine Chemistry by the Satellite Spectrometers GOME and SCIAMACHY, Dr. rer nat, Institute of Environmental Physics, University of Heidelberg, Heidelberg, 2005. Kühl, S., Dornbrack, A., Wilms Grabe, W., Sinnhuber, B. M., Platt, U., and Wagner, T.: Observational evidence of rapid chlorine activation by mountain waves above northern Scandinavia, J. Geophys. Res.-Atmos., 109, 1–18, 2004a. Kühl, S., Wilms-Grabe, W., Beirle, S., Frankenberg, C., Grzegorski, M., Hollwedel, J., Khokhar, F., Kraus, S., Platt, U., Sanghavi, S., von Friedeburg, C., and Wagner, T.: Stratospheric chlorine activation in the Arctic winters 1995/1996–2001/2002 derived from GOME OClO measurements, Trace Constituents in the Troposphere and Lower Stratosphere, 34, 798–803, 2004b. Kühl, S., Pukite, J., Deutschmann, T., Platt, U., and Wagner, T.: SCIAMACHY limb measurements of NO<sub>2</sub>, BrO and OClO, Retrieval of vertical profiles: Algorithm, first results, sensitivity and comparison studies, Adv. Space Res., 42, 1747–1764, doi:10.1016/j.asr.2007.10.022, 2008. Lary, D. J.: Catalytic Destruction of Stratospheric Ozone, J. Geophys. Res., 102, 21515–21526, 1997. Maric, D., Burrows, J. P., and Moortgat, G. K.: A Study of the UV-Visible Absorption-Spectra of Br<sub>2</sub> and BrCl, J. Photochem. Photobiol. A-Chem., 83, 179–192, 1994. McElroy, M. B., Salawitch, R. J., Wofsy, S. C., and Logan, J. A.: Reduction of Antarctic ozone due to synergistic interactions of chlorine and bromine, Nature, 321, 759–762, 1986. McKeachie, J. R., Appel, M. F., Kirchner, U., Schindler, R. N., and Benter, T.: Observation of a heterogeneous source of OClO from the reaction of ClO radicals on ice, J. Phys. Chem. B, 108, 16786–16797, 2004. Nickolaisen, S. L., Friedl, R. R., and Sander, S. P.: Kinetics and Mechanism of the ClO + ClO Reaction – Pressure and Temperature Dependences of the Bimolecular and Termolecular Channels and Thermal-Decomposition of Chlorine Peroxide, J. Phys. Chem., 98, 155–169, 1994. Otten, C., Ferlemann, F., Platt, U., Wagner, T., and Pfeilsticker, K.: Groundbased DOAS UV/visible measurements at Kiruna (Sweden) during the SESAME winters 1993/1994 and 1994/1995, J. Atmos. Chem., 30, 141–162, 1998. Permien, T., Vogt, R., and Schindler, R. N.: Mechanisms of Gas Phase-Liquid Phase Chemical Transformations, in: Air Pollution Report #17, edited by: Cox, R. A., Environmental Research Program of the CEC, Brussels, 1988. Perner, D., Roth, A., and Klüpfel, T.: Groundbased measurements of stratospheric OClO, NO<sub>2</sub>, and O<sub>3</sub> at Søndre Strømfjord in winter 1991/1992, Geophys. Res. Lett., 21, 1367–1370, 1994. Pierson, J. M., McKinney, K. A., Toohey, D. W., Margitan, J., Schmidt, U., Engel, A., and Newman, P. A.: An investigation of ClO photochemistry in the chemically perturbed arctic vortex, J. Atmos. Chem., 32, 61–81, 1999. Plenge, J., Flesch, R., Kühl, S., Vogel, B., Muller, R., Stroh, F., and Ruhl, E.: Ultraviolet photolysis of the CIO dimer, J. Phys. Chem. A, 108, 4859–4863, doi:10.1021/jp049690, 2004. Plenge, J., Kühl, S., Vogel, B., Muller, R., Stroh, F., von Hobe, M., Flesch, R., and Ruhl, E.: Bond strength of chlorine peroxide, J. Phys. Chem. A, 109, 6730–6734, doi:10.1021/jp044142h, 2005. Pommereau, J. P. and Piquard, J.: Ozone and nitrogen dioxide vertical distributions by UV-visible solar occultation from balloons, Geophys. Res. Lett., 21, 1227–1230, 1994. Pope, F. D., Hansen, J. C., Bayes, K. D., Friedl, R. R., and Sander, S. P.: Ultraviolet absorption spectrum of chlorine peroxide, ClOOCl, J. Phys. Chem. A, 111, 4322–4332, doi:10.1021/jp067660w, 2007. Renard, J. B., Lefevre, F., Pirre, M., Robert, C., and Huguenin, D.: Verticle profile of night-time stratospheric OClO, J. Atmos. Chem., 26, 65–76, 1997. Richter, A., Eisinger, M., Ladstätter-Weißenmayer, A., and Burrows, J. P.: DOAS Zenith sky observations: 2. Seasonal variation of BrO over Bremen (53° N) 1994–1995, J. Atmos. Chem., 32, 83–99, 1999. Richter, A., Wittrock, F., Weber, M., Beirle, S., Kühl, S., Platt, U., Wagner, T., Wilms-Grabe, W., and Burrows, J. P.: GOME observations of stratospheric trace gas distributions during the splitting vortex event in the Antarctic winter of 2002, Part I: Measurements, J. Atmos. Sci., 62, 778–785, 2005. Riviere, E. D., Pirre, M., Berthet, G., Renard, J. B., Taupin, F. G., Huret, N., Chartier, M., Knudsen, B., and Lefevre, F.: On the interaction between nitrogen and halogen species in the Arctic polar vortex during THESEO and THESEO 2000, J. Geophys. Res.-Atmos., 108(D5), 8311, doi:10.1029/2002JD002087, 2003. Rozanov, A., Rozanov, V., and Burrows, J. P.: A numerical radiative transfer model for a spherical planetary atmosphere: combined differential-integral approach involving the Picard iterative approximation, J. Quant. Spectros. Ra., 69, 491–512, 2001. Rozanov, A., Rozanov, V., Buchwitz, M., Kokhanovsky, A., and Burrows, J. P.: SCIATRAN 2.0 – A new radiative transfer model for geophysical applications in the 175–2400 nm spectral region, Adv. Space Res., 36, 1015–1019, doi:10.1016/j.asr.2005.03.012, 2005. Sander, S. P., Friedel, R. R., Golden, D. M., Kurylo, M. J., Huie, R. E., Orkin, V. L., Moortgat, G. K., Ravishankara, A. R., Kolb, C. E., Molina, M. J., and Finlayson-Pitts, B. J.: Chemical Kinetics and Photochemical Data for Use in Atmospheric Studies – Evaluation Number 14, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, 2003. Sander, S. P., Friedel, R. R., Golden, D. M., Kurylo, M. J., Moortgat, G. K., Keller-Rudek, H., Wine, P. H., Ravishankara, A. R., Kolb, C. E., Molina, M. J., Finlayson-Pitts, B. J., Huie, R. E., and Orkin, V. L.: Chemical Kinetics and Photochemical Data for Use in Atmospheric Studies – Evaluation Number 15, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, 2006. Sanders, R. W., Solomon, S., Smith, J. P., Perliski, L., Miller, H. L., Mount, G. H., Keys, J. G., and Schmeltekopf, A. L.: Visible and near-ultraviolet spectroscopy at McMurdo Station, Antarctica 9. Observations of OClO from April to October 1991, J. Geophy. Res., 98, 7219–7228, 1993. Santee, M. L., MacKenzie, I. A., Manney, G. L., Chipperfield, M. P., Bernath, P. F., Walker, K. A., Boone, C. D., Froidevaux, L., Livesey, N. J., and Waters, J. W.: A study of stratospheric chlorine partitioning based on new satellite measurements and modeling, J. Geophys. Res.-Atmos., 113, 25, D12307, doi:10.1029/2007jd009057, 2008. Schiller, C. and Wahner, A.: Comment on "Stratospheric OClO measurements as a poor quanitatative indicator of chlorine activation", Geophys. Res. Lett., 23, 1053–1054, 1996. Schiller, C., Wahner, A., Platt, U., Dorn, H. P., Callies, J., and Ehhalt, D. H.: Near UV atmospheric absorption measurements of column abundances during Airborne Arctic Stratospheric Expedition, January-February 1989: 2. OClO observations, Geophys. Res. Lett., 17, 501–504, 1990. Schofield, R., Johnston, P. V., Thomas, A., Kreher, K., Connor, B. J., Wood, S., Shooter, D., Chipperfield, M. P., Richter, A., von Glasow, R., and Rodgers, C. D.: Tropospheric and stratospheric BrO columns over Arrival Heights, Antarctica, 2002, J. Geophys. Res.-Atmos., 111, 14, D22310, doi:10.1029/2005jd007022, 2006. Schofield, R., Frieler, K., Wohltmann, I., Rex, M., von Hobe, M., Stroh, F., Koch, G., Peter, T., Canty, T., Salawitch, R., and Volk, C. M.: Polar stratospheric chlorine kinetics from a self-match flight during SOLVE-II/EUPLEX, Geophys. Res. Lett., 35(6), L01807, doi:10.1029/2007gl031740, 2008. Sinnhuber, B. M., Arlander, D. W., Bovensmann, H., Burrows, J. P., Chipperfield, M. P., Enell, C. F., Frieß, U., Hendrick, F., Johnston, P. V., Jones, R. L., Kreher, K., Mohamed-Tahrin, N., Muller, R., Pfeilsticker, K., Platt, U., Pommereau, J. P., Pundt, I., Richter, A., South, A. M., Tørnkvist, K. K., Van Roozendael, M., Wagner, T., and Wittrock, F.: Comparison of measurements and model calculations of stratospheric bromine monoxide, J. Geophys. Res.-Atmos., 107, 4398, doi:10.1029/2001JD000940, 2002. Sinnhuber, B. M., Rozanov, A., Sheode, N., Afe, O. T., Richter, A., Sinnhuber, M., Wittrock, F., Burrows, J. P., Stiller, G. P., von Clarmann, T., and Linden, A.: Global observations of stratospheric bromine monoxide from SCIAMACHY, Geophys. Res. Lett., 32, L20810, doi:10.1029/2005GL023839, 2005. Soller, R., Nicovich, J. M., and Wine, P. H.: Temperature-dependent rate coefficients for the reactions of Br(<sup>2</sup>P$_3/2)$, Cl(<sup>2</sup>P$_3/2)$, and O(<sup>3</sup>P$_J)$ with BrONO<sub>2</sub>, J. Phys. Chem. A, 105, 1416–1422, 2001. Solomon, S., Mount, G. H., Sanders, R. W., and Schmeltekopf, A. L.: Visible Spectroscopy at McMurdo Station, Antarctica – 2. Observations of OClO, J. Geophys. Res., 92, 8329–8338, 1987a. Solomon, S., Schmeltekopf, A. L., and Sanders, R. W.: On the Interpretation of Zenith Sky Absorption Measurements, J. Geophys. Res., 92, 8311–8319, 1987b. Solomon, S., Mount, G. H., Sanders, R. W., Jakoubek, R. O., and Schmeltekopf, A. L.: Observations of the nighttime abundance of OClO in the winter stratosphere above Thule, Greenland, Science, 242, 550–555, 1988. Solomon, P., Barrett, J., Connor, B., Zoonematkermani, S., Parrish, A., Lee, A., Pyle, J., and Chipperfield, M.: Seasonal observations of chlorine monoxide in the stratosphere over Antarctica during the 1996–1998 ozone holes and comparison with the SLIMCAT three-dimensional model, J. Geophys. Res.-Atmos., 105, 28979–29001, 2000. Stimpfle, R. M., Wilmouth, D. M., Salawitch, R. J., and Anderson, J. G.: First measurements of ClOOCl in the stratosphere: The coupling of ClOOCl and ClO in the Arctic polar vortex, J. Geophys. Res.-Atmos., 109(16), D03301, doi:10.1029/2003jd003811, 2004. Tellinghuisen, J.: Precise equilibrium constants from spectrophotometric data: BrCl in Br<sub>2</sub>/Cl<sub>2</sub> gas mixtures, J. Phys. Chem. A, 107, 753–757, doi:10.1021/jp027227w, 2003. Theys, N., Van Roozendael, M., Hendrick, F., Fayt, C., Hermans, C., Baray, J.-L., Goutail, F., Pommereau, J.-P., and De Mazire, M.: Retrieval of stratospheric and tropospheric BrO columns from multi-axis DOAS measurements at Reunion Island (21° S, 56° E), Atmos. Chem. Phys., 7, 4733–4749, doi:10.5194/acp-7-4733-2007, 2007. Thornton, B. F., Toohey, D. W., Avallone, L. M., Harder, H., Martinez, M., Simpas, J. B., Brune, W. H., and Avery, M. A.: In situ observations of ClO near the winter polar tropopause, J. Geophys. Res.-Atmos., 108(8), 8333, doi:10.1029/2002jd002839, 2003. Thornton, B. F., Toohey, D. W., Avallone, L. M., Hallar, A. G., Harder, H., Martinez, M., Simpas, J. B., Brune, W. H., Koike, M., Kondo, Y., Takegawa, N., Anderson, B. E., and Avery, M. A.: Variability of active chlorine in the lowermost Arctic stratosphere, J. Geophys. Res.-Atmos., 110(11), D22304, doi:10.1029/2004jd005580, 2005. Tørnkvist, K. K., Arlander, D. W., and Sinnhuber, B. M.: Ground-based UV measurements of BrO and OClO over Ny-Ålesund during winter 1996 and 1997 and Andøya during winter 1998/1999, J. Atmos. Chem., 43, 75–106, 2002. Trolier, M., Mauldin, R. L., and Ravishankara, A. R.: Rate Coefficient for the Termolecular Channel of the Self-Reaction of ClO, J. Phys. Chem., 94, 4896–4907, 1990. Tung, K. K., Ko, M. K. W., Rodriguez, J. M., and Sze, N. D.: Are Antarctic ozone variations a manifestation of dynamics or chemistry?, Nature, 322, 811–814, 1986. Vandaele, A. C., Hermans, C., Fally, S., Carleer, M., Merienne, M. F., Jenouvrier, A., Coquart, B., and Colin, R.: Absorption cross-sections of NO<sub>2</sub>: simulation of temperature and pressure effects, Journal of J. Quant. Spectros. Ra., 76, 373–391, 2003. Vandaele, A. C., Fayt, C., Hendrick, F., Hermans, C., Humbled, F., Van Roozendael, M., Gil, M., Navarro, M., Puentedura, O., Yela, M., Braathen, G., Stebel, K., Tornkvist, K., Johnston, P., Kreher, K., Goutail, F., Mieville, A., Pommereau, J. P., Khaikine, S., Richter, A., Oetjen, H., Wittrock, F., Bugarski, S., Frieß, U., Pfeilsticker, K., Sinreich, R., Wagner, T., Corlett, G., and Leigh, R.: An intercomparison campaign of ground-based UV-visible measurements of NO<sub>2</sub>, BrO, and OClO slant columns: Methods of analysis and results for NO<sub>2</sub>, J. Geophys. Res.-Atmos., 110(26), D08305, doi:10.1029/2004jd005423, 2005. Vogel, B., Muller, R., Deshler, T., Grooss, J. U., Karhu, J., McKenna, D. S., Muller, M., Toohey, D., Toon, G. C., and Stroh, F.: Vertical profiles of activated ClO and ozone loss in the Arctic vortex in January and March 2000: In situ observations and model simulations, J. Geophys. Res.-Atmos., 108(19), 8334, doi:10.1029/2002jd002564, 2003. von Hobe, M., Grooß, J.-U., Müller, R., Hrechanyy, S., Winkler, U., and Stroh, F.: A re-evaluation of the ClO/Cl<sub>2</sub>O<sub>2</sub> equilibrium constant based on stratospheric in-situ observations, Atmos. Chem. Phys., 5, 693–702, doi:10.5194/acp-5-693-2005, 2005. von Hobe, M., Salawitch, R. J., Canty, T., Keller-Rudek, H., Moortgat, G. K., Groo, J.-U., Müller, R., and Stroh, F.: Understanding the kinetics of the ClO dimer cycle, Atmos. Chem. Phys., 7, 3055–3069, doi:10.5194/acp-7-3055-2007, 2007. Vountas, M., Rozanov, V. V., and Burrows, J. P.: Ring effect: Impact of rotational Raman scattering on radiative transfer in earth's atmosphere, J. Quant. Spectros. Ra., 60, 943–961, 1998. Wagner, T., Leue, C., Pfeilsticker, K., and Platt, U.: Monitoring of the stratospheric chlorine activation by Global Ozone Monitoring Experiment (GOME) OClO measurements in the austral and boreal winters 1995 through 1999, J. Geophys. Res.-Atmos., 106, 4971–4986, 2001. Wagner, T., Wittrock, F., Richter, A., Wenig, M., Burrows, J. P., and Platt, U.: Continuous monitoring of the high and persistent chlorine activation during the Arctic winter 1999/2000 by the GOME instrument on ERS-2, J. Geophys. Res.-Atmos., 107, 8267, doi:10.1029/2001JD000466, 2002. Wagner, T., Burrows, J. P., Deutschmann, T., Dix, B., von Friedeburg, C., Frieß, U., Hendrick, F., Heue, K.-P., Irie, H., Iwabuchi, H., Kanaya, Y., Keller, J., McLinden, C. A., Oetjen, H., Palazzi, E., Petritoli, A., Platt, U., Postylyakov, O., Pukite, J., Richter, A., van Roozendael, M., Rozanov, A., Rozanov, V., Sinreich, R., Sanghavi, S., and Wittrock, F.: Comparison of box-air-mass-factors and radiances for Multiple-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) geometries calculated from different UV/visible radiative transfer models, Atmos. Chem. Phys., 7, 1809–1833, doi:10.5194/acp-7-1809-2007, 2007. Wahner, A., Tyndall, G. S., and Ravishankara, A. R.: Absorption cross sections for OClO as a function of temperature in the wavelength range 240-480 nm, J. Phys. Chem., 91, 2734–2738, 1987. Wahner, A., Jakoubek, R. O., Mount, G. H., Ravishankara, A. R., and Schmeltekopf, A. L.: Remote sensing observations of nighttime OClO column during the Airborne Antarctic Ozone Experiment, 8~September~1987, J. Geophys. Res., 94, 11405–11411, 1989. Wilmouth, D. M., Hanisco, T. F., Donahue, N. M., and Anderson, J. G.: Fourier Transform Ultraviolet Spectroscopy of the A$^2\Pi _3/2$ ← X$^2\Pi _3/2$ Transition of BrO, J. Phys. Chem. A, 103, 8935–8945, 1999. Wittrock, F., Oetjen, H., Richter, A., Fietkau, S., Medeke, T., Rozanov, A., and Burrows, J. P.: MAX-DOAS measurements of atmospheric trace gases in Ny-Ålesund – Radiative transfer studies and their application, Atmos. Chem. Phys., 4, 955–966, doi:10.5194/acp-4-955-2004, 2004. WMO: Scientific Assessment of Ozone Depletion: 2006, World Meteorological Organization, Geneva, 2007. Yung, Y. L., Pinto, J. P., Watson, R. Z., and Sander, S. P.: Atmospheric Bromine and Ozone Perturbations in the Lower Stratosphere, J. Atmos. Sci., 37, 339–353, 1980.