The partitioning of reactive nitrogen species (NOy) in the stratosphere during the Arctic Winter 1998/99 : modelling with the Chemical Lagrangian Model of the Stratosphere (CLaMS) - Bausch, S.; Grooß, J.-U.; Steinhorst, H.; Konopka, Paul; Müller, R.; Oelhaf, H.; Stowasser, M.; Friedl-Vallon, F.; Lefèvre, F. (2003)