Das Projekt "Towards the prediction of stratospheric ozone III: the partitioning of the NOy-components (EU-Projekt)" wird vom Umweltbundesamt gefördert und von Universität Karlsruhe, Institut für Meteorologie und Klimaforschung durchgeführt. Towards the prediction of Stratospheric Ozone III (TOPOZ III) The partitioning of the NOy components The partitioning of reactive nitrogene species (NOy) in the winter stratosphere is only poorly understood. This limits the scientific reliability of predictions of the ozone layer over decades. This project analyses the NOy partitioning using data from the MIPAS balloon experiment, the ENVISAT instruments MIPAS and SCIAMACHY operationally provided by ESA, and retrieved to a higher degree by UKARL, CSIC and UHB, which are compared to results of a variety of chemical transport models and data assimilation models. This comparison leads to improvements of the models involved which are passed to the CCM models of the DLR and ULAQ. Finally, these groups perform predictions of the ozone layer with a significant higher scientific reliability.