The main objective of the project ANNA is to analyze aerosol transport patterns from northern Europe into the Arctic in order to find correlations between anthropogenic aerosol sources in central and northern Europe and spring time aerosol occurrences in the European Arctic, called Arctic haze. This correlation has been suggested in the literature for several decades but recently been questioned based on extensive trajectory analysis. This project will strengthen the knowledge on Arctic haze formation by delivering optical remote sensing data of aerosols in the so far sparsely surveyed northern European atmosphere. Concentrating on two campaign periods in spring 2013 and 2014, a comprehensive Raman lidar data set based on data from five measurement sites will be achieved and evaluated regarding aerosol occurrences and characteristics in order to either support or reject the Arctic haze origin hypothesis. The project will be conducted by Anne Hoffmann at the Finnish Meteorological Institute (FMI) in Kuopio in cooperation with three other institutions originating in Norway, Germany and Poland, which all operate Raman lidar measurement sites in northern Europe or on Svalbard. Match cases, in which the same air mass has been probed above two lidar stations, will be identified using trajectory analysis and the temporal development of the aerosol particle characteristics on their way into the Arctic will be investigated. The resulting data set will be made available to the scientific community and will be used to validate the aerosol module SALSA, which has been developed at FMI and is used in global climate models. ANNA is scheduled as a two year joined intra-European project, which will close the gap of remote sensing aerosol data between central Europe and the Arctic and improve the state of knowledge on anthropogenic sources of Arctic haze.