Overview of the research activities and results at Puijo semi-urban measurement station

We introduce a new measurement station that we established in 2005 in an observation tower at Puijo in Kuopio. At Puijo we measure several meteorological parameters, aerosol and cloud droplet size distribution, aerosol optical properties and trace gas concentrations. We summarize the research activities at the station during its three-year history and present overall results. We compare the results from Puijo with those measured at the ground level in Kuopio and at the Finnish background stations. We also characterize the measured parameters according to the wind direction and air mass origins, based on trajectory analysis, for the effects of local and remote sources. Our conclusion is that the Puijo tower is a very good place to gather experimental data on cloud formation and aerosol–cloud interaction. In addition to cloud experiments, we would suggest the Puijo measurement station for studies of particle formation, which we also observed frequently.