Groundbased measurements of stratospheric OClO, NO2, and O3 at Søndre Strømfjord in winter 1991/92

Experiment (EASOE) campaign Within the scope of the 1991/92 European Arctic Stratospheric Ozone stratospheric chlorine dioxide, OClO, nitrogen dioxide, NO2, bromine monoxide, BrO, and ozone, O3, were measured by groundbased UV-VIS remote sensing in Sondre Stromfjord, Greenland (50.4°W, 67.0°N). The measurement period was from the middle of November 1991 until the end of January 1992. The anticipated correlation between potential vorticity and OClO appeared less pronounced in the beginning and its abundance was similar inside and outside of the polar vortex. During November 1991 stratospheric temperatures throughout the polar region were still above threshold for polar stratospheric cloud (PSC) formation. During January when NO2 column densities were at their lowest, OClO inside of the vortex appeared to be highly variable. Average vertical column densities reached about 1013 molec cm−2, less than found in previous years. The chemistry as well as the observations may have been disturbed by the aerosol cloud from Mt. Pinatubo eruption.