Title First remote sensing measurements of ClOOCl along with ClO and ClONO2 in activated and deactivated Arctic vortex conditions using new ClOOCl IR absorption cross sections
Author Wetzel, G.; Oelhaf, H.; Kirner, O.; Ruhnke, R.; Friedl-Vallon, F.; Kleinert, A.; Maucher, G.; Fischer, H.; Birk, M.; Wagner, G.; Engel, A.
Author Affil Wetzel, G., Karlsruher Institut für Technologie, Institut für Meteorologie und Klimaforschung, Karlsruhe, Germany. Other: Deutsches Zentrum für Luft und Raumfahrt, Germany; Johann Wolfgang Goethe Universität Frankfurt am Main, Germany
Source Atmospheric Chemistry and Physics, 10(3), p.931-945, . Publisher: Copernicus, Katlenburg-Lindau, International. ISSN: 1680- 7316
Publication Date 2010
Notes In English. Published in Atmospheric Chemistry and Physics Discussions: 25 September 2009, http://www.atmos-chem-phys- discuss.net/9/20103/2009/acpd-9-20103-2009.ht ml; accessed in May, 2011. 53 refs. GeoRef Acc. No: 310105
Index Terms altitude; clouds (meteorology); ozone; remote sensing; spectra; stratosphere; Arctic region; Sweden--Kiruna; atmosphere; catalysis; chemical reactions; chloride oxide; chlorine; chlorine monoxide; clouds; depletion; Europe; general circulation models; halogens; hydrogen chloride; infrared spectra; Kiruna Sweden; mixing; Norrbotten Sweden; Scandinavia; seasonal variations; sensitivity analysis; Sweden; Western Europe
Abstract Active chlorine species play a dominant role in the catalytic destruction of stratospheric ozone in the polar vortices during the late winter and early spring seasons. Recently, the correct understanding of the ClO dimer cycle was challenged by the release of new laboratory absorption cross sections (Pope et al., 2007) yielding significant model underestimates of observed ClO and ozone loss (von Hobe et al., 2007). Under this aspect, nocturnal Arctic stratospheric limb emission measurements carried out by the balloon version of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS-B) from Kiruna (Sweden) on 11 January 2001 and 20/21 March 2003 have been reanalyzed with regard to the chlorine reservoir species ClONO2 and the active species, ClO and ClOOCl (Cl2O2). New laboratory measurements of IR absorption cross sections of ClOOCl for various temperatures and pressures allowed for the first time the retrieval of ClOOCl mixing ratios from remote sensing measurements. High values of active chlorine (ClOx) of roughly 2.3 ppbv at 20 km were observed by MIPAS-B in the cold mid-winter Arctic vortex on 11 January 2001. While nighttime ClOOCl shows enhanced values of nearly 1.1 ppbv at 20 km, ClONO2 mixing ratios are less than 0.1 ppbv at this altitude. In contrast, high ClONO2 mixing ratios of nearly 2.4 ppbv at 20 km have been observed in the late winter Arctic vortex on 20 March 2003. No significant ClOx amounts are detectable on this date since most of the active chlorine has already recovered to its main reservoir species ClONO2. The observed values of ClOx and ClONO2 are in line with the established polar chlorine chemistry. The thermal equilibrium constants between the dimer formation and its dissociation, as derived from the balloon measurements, are on the lower side of reported data and in good agreement with values recommended by von Hobe et al. (2007). Calculations with the ECHAM/MESSy Atmospheric Chemistry model (EMAC) using established kinetics show similar chlorine activation and deactivation, compared to the measurements in January 2001 and March 2003, respectively.
URL http://www.atmos-chem-phys.net/10/931/2010/acp-10-931-2010.pdf
Publication Type journal article
Record ID 65006748