As part of the GAW programme, Denmark contributes to the Global Ozone Observing System (GO3OS) with three stations in Greenland and one in Denmark. The stations in Greenland are: Kangerlussuaq, Pituffik and Illoqqortoormiut The station in Denmark is located in Copenhagen The stations in Greenland are primary and secondary stations in the Network for the Detection of Stratospheric Change (NDSC) that is supported by the International Ozone Commission.