Active ClOx species and ClONO2 as measured by MIPAS-B inside the Arctic vortex in winters 2001 and 2003

The ClO dimer cycle is one of the most important cycles for the catalytic destruction of stratospheric ozone in the polar vortices during the late winter and early spring seasons. Recently, the correct understanding of this cycle was challenged by the release of new laboratory absorption cross sections yielding to significant model underestimates of observed ClO and ozone loss (see, e.g. von Hobe et al., 2007). Under this aspect, arctic stratospheric limb emission measurements carried out by the balloon version of the Michelsen 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 ClOx species ClO and Cl2O2. Retrieved trace gas profiles are discussed and compared to simulations performed with the 3-dimensional Chemistry Transport Model KASIMA