Long path measurements of atmospheric sulphur dioxide by a barringer cospec® III

Abstract Time fluctuations of ground level concentrations of atmospheric sulphur dioxide have been successfully measured over distances of up to 1 km, using a Cospec® III (Barringer Research, Canada) aligned on a modulated xenon lamp. Experiments have been carried out on hills at Ispra, at Milan airport, near a large refinery (Lacq, France) and around a power station (Drax, England) at heights from 1.7 to 30m above the ground. Using an artificial light source, measurements can be made over a 24 hr period, and under non-ideal meteorological conditions (rain, haze, etc.). The detection limit is 5 ppb over a 1 km path. The agreement of average long path data between the remote sensor and point samplers is quite satisfactory. Long path measurements can be applied to air quality measurements in urban areas as well as to monitoring and modelling the pollutant diffusion and fall-out around a plant.