Development of an excimer laser-based Raman lidar for tropospheric ozone concentration measurements

A ground based Raman Lidar is being developed for daytime and nighttime ozone monitoring in the lower troposphere (0.2–2 km). The system unitizes a 30&inches; Cassegrain telescope and a KrF excimer laser transmitter operating at 248 nm and up to 15 W average power. The physics governing the system is based on Raman scattering of the laser photons by N₂ at 263 nm and O₂ at 258 nm and the attenuation of the laser and Raman back-scattered photons by ozone absorption. To obtain the ozone concentration, we calculate the single and double ratio of the Raman Scattered signals throughout the range. It is shown that the system gives accurate results when validated by deducing relative scattering cross sections from data obtained in a field environment. Values that are obtained for the relative Raman scattering cross sections of O₂ and N₂ are within the range of measurements previously reported in the literature by other authors. The results indicate that refinement of the techniques will allow measuring distributions of lower tropospheric O₃ over ranges up to 3 km using our system.