Aura Microwave Limb Sounder observations of the 2004-2005 Arctic winter: ozone evolution and chemical loss.

Because of extensive chlorine activation during the unusually cold 2004-2005 Arctic winter, as discussed in a companion talk by Santee et al., substantial wintertime ozone depletion is expected. We show here the evolution of ozone observed by the Aura Microwave Limb Sounder (MLS) instrument throughout the 2004-2005 Arctic winter. Related MLS observations, especially nitrous oxide, along with meteorological analyses and trajectory calculations, are used to detail dynamical and transport processes affecting ozone, and thus distinguish them from chemical changes. Results from MLS observations are also compared with calculations from the SLIMCAT chemistry-transport model.