In preparation to the launch of the SAGE III experiment in March 2001, NASA and the European Union performed the SOLVE / THESEO-2000 campaign, which had three components: (i) an aircraft campaign using the NASA DC-8 and ER-2 airplanes out of Kiruna/Sweden, (ii) launches of large stratospheric research balloons from Kiruna, (iii) validation excercises for the commissioning phase of SAGE III. The German Arctic research station Koldewey in Ny-Ålesund/Spitsbergen contributes to (i), (ii), and (iii) by performing measurements of stratospheric components like ozone, trace gases, aerosols (PSCs), temperature and winds. The measurement results were transmitted quasi online to the flight planning center in Kiruna, in order to allow a better directing of the air plane flights. In addition the Koldewey-Station has been designated a validation anchor site for the SAGE III validation. The activities are organized within a NASA accepted proposal of ground-based validation support by the NDSC Primary Station at Ny-Ålesund, Spitsbergen and by a SAGE III validation working group for Ny-Ålesund. The main observation periods are from December 1999 to March 2000.