HR: 1340h
AN: A13D-0978    [Abstracts]
TI: The Potential Impact of ClOx Radical Complexes on Polar Stratospheric Ozone Loss Processes
AU: Vogel, B
EM: b.vogel@fz-juelich.de
AF: Institute for Stratospheric Chemistry (ICG-I), Forschungszentrum Juelich GmbH (FZJ), Juelich, D-52425 Germany
AU: Chipperfield, M
EM: martyn@env.leeds.ac.uk
AF: School of Earth and Environment, University of Leeds, Leeds, LS2 9JT United Kingdom
AU: * Grooss, J
EM: j.-u.grooss@fz-juelich.de
AF: Institute for Stratospheric Chemistry (ICG-I), Forschungszentrum Juelich GmbH (FZJ), Juelich, D-52425 Germany
AU: Streibel, M
EM: Martin.Streibel@ozone-sec.ch.cam.ac.uk
AF: Alfred Wegener Institute for Polar and Marine Research, Telegrafenberg A43, Potsdam, D-14473 Germany
AU: Streibel, M
EM: Martin.Streibel@ozone-sec.ch.cam.ac.uk
AF: European Ozone Research Coordinating Unit University of Cambridge Department of Chemistry, Lensfield Road, Cambridge, CB2 1EW United Kingdom
AU: Mueller, R
EM: ro.mueller@fz-juelich.de
AF: Institute for Stratospheric Chemistry (ICG-I), Forschungszentrum Juelich GmbH (FZJ), Juelich, D-52425 Germany
AB: The importance of radical-molecule complexes for atmospheric chemistry has been discussed in recent years. In particular, the existence of a ClO · O₂ and ClO_x water radical complexes like ClO · H₂O, OClO · H₂O, OClO · (H₂O)₂, and ClOO · H₂O could play a role in enhancing the ClO dimer (Cl₂O₂) formation and therefore may constitute an important intermediate in polar stratospheric ozone loss cycles. Model simulations performed with the Chemical Lagrangian Model of the Stratosphere (CLaMS) will be presented to study the role of radical complexes on polar stratospheric ozone loss processes. The model simulations are performed for the Arctic winter 2002/2003 at a level of 500 K potential temperature and the results are compared to observed ozone loss rates determined by the Match technique. Moreover, recently reported values for the equilibrium constant of the ClO dimer formation are used to restrict the number of possible model results caused by the large uncertainties about radical complex chemistry. Assuming that the binding energies of the ClO_x water complexes are much higher than theoretically predicted an enhancement of the ozone loss rate by up to ~ 0.5 ppb/sunlight h is simulated. Because it is unlikely that the ClO_x water complexes are much more stable than predicted we conclude that these complexes have no impact on polar stratospheric ozone loss processes. Further, our model simulations show that the potential impact of ClO · O₂ on polar ozone loss processes is very small (dO₃/dt << 0.5 ppb/sunlight h) provided that the ClO · O₂ complex is only weakly stable. Although large uncertainties about radical complex chemistry exist, our findings show that, considering pure gas-phase chemistry, the potential impact of radical molecule complexes on polar stratospheric ozone loss processes is very small.
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 0317 Chemical kinetic and photochemical properties
DE: 0340 Middle atmosphere: composition and chemistry
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005