First results of ground‐based FTIR measurements of atmospheric trace gases in north Sweden and Greenland during EASOE

Zenith column amounts of N 2 O, CH 4 , CFC‐12, O 3 , HNO 3 , ClONO 2 , HCl, and HF were measured by ground‐based FTIR spectrometers at Kiruna in November 1991 and from January to March 1992, and in January and March 1992 in Sondre Stromfjord, Greenland. They were correlated to the dynamical situation of the stratosphere and interpreted in terms of chemical processes, with respect to the position of the vortex, the stratospheric temperatures, and the trajectories of the air masses for the last ten days. One of the most remarkable results is the increasing ClONO 2 burden from the end of January to mid‐March, reaching the extremely high value of 7.2 × 10 15 molec./cm².