Lidar measurements of ozone, aerosol and temperature in the stratosphere

The focus of this thesis is on differential absorption lidar (DIAL) measurements of stratospheric ozone. However, aerosol and temperature are important quantities that can be measured as well. An in depth discussion of key points relevant to DIAL measurements is presented and observations are reported from state-of-the-art DIAL systems in Toronto and in the Canadian Arctic (Eureka, 80;A central issue for lidar measurements is the linearity of the signal recording technique. For the first time actual atmospheric returns are used to quantitatively describe the nonlinearities occurring at very high and very low count rates, which can significantly affect the precision of an ozone DIAL system above 40 km. Methods are developed to overcome these problems in routine measurements. Their success is demonstrated by one of the best reported agreements (better than 2% at most altitudes) between the lidar and SAGE II ozone profiles.;Aerosol-related errors in DIAL ozone profiles have become a very important issue after the Mt. Pinatubo volcanic eruption in June 1991. This thesis presents one of first available in depth treatments. Mie calculations, based on the largest available data set of aerosol size distributions from the University of Wyoming, are used to investigate these errors and possible correction schemes. Even after a correction the ozone error can reach 50% and more. However, in the future the use of Raman return signals from atmospheric N;Despite aerosol-related problems in the 15 to 28 km range, high quality measurements have been made up to 50 km altitude over three years in Toronto and two months in Eureka. Highlights from the measurements in Toronto include the low mixing ratios observed in 1992 and 1993. They may point to a change in atmospheric circulation in the upper stratosphere, explaining the low total ozone values observed at this time. The Eureka data show incredible changes in ozone, temperature and aerosol over very short times, related to the movement of the polar vortex. One of the many new and interesting aspects of the Eureka data-set is the observation of ozone-rich layers between 35 and 50 km, which seem to precede stratospheric warmings.