| Summary: | Infrared and UV/visible broadband absorption techniques have been used in three applications related to environmental research and atmospheric science. The techniques are based on measuring the attenuation of light by the atmosphere in the infrared and UV/visible region, and since a very large number of species absorb light in these wavelength regions, the techniques studied allow the measurement of several species simultaneously. Measurements of high resolution infrared solar spectra have been conducted during 1995 to 1998 at an observatory in Norway (60.2oN, 10.75oE). From the solar spectra, atmospheric columns of O3 and the most abundant nitrogen, chlorine and fluorine species in the stratosphere have been retrieved, such as: HCl, ClONO2, ClO, HNO3, N2O, HF and COF2. In addition, height concentration profiles of HCl, O3, HF, N2O and CH4 have been retrieved from the spectra. These were compared to several other techniques, indicating uncertainties of 10-20% at 20 km decreasing both upwards and downwards in altitude. Chlorine activation, i.e. conversion of the reservoir species HCl and ClONO2 to ClO on ice particles in the stratosphere, could be quantified on several occasions during the measurement period. The measurements also indicated significant ozone depletion in the Arctic polar stratosphere of 1995. In the second application a new method for quantitative estimation of fugitive emissions of hydrocarbons from petrochemical industries has been developed. Tracer gases are released on the location of the leakages, and then concentration measurements are conducted downwind, over a long atmospheric path, by infrared absorption technique. What is unique with the method is a new approach based on the correlation of the tracer and the source gas concentrations over time. The method has been used to measure diffuse emissions of ethylene and propylene at several industrial sites during 1994 to 1998. Sensitivity experiments and comparison with other techniques indicate the possibility of 20% accuracy for flux ...
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