Differential absorption lidar probing of atmospheric ozone over a tropical urban station in India

An ultra-violet (UV) rare-gas halide XeCl excimer-Raman laser-based ozone lidar system has been developed and installed at the Indian Institute of Tropical Meteorology (IITM), Pune (18°43'N, 73°51'E, 559 m above mean sea level), India. This system essentially operates in the differential-absorption-lidar (DIAL) mode with laser emission at 308 nm ('on') wavelength as well as reference ('off') wavelength of 353 nm generated by stimulated Raman shifting (SRS) the 308 nm radiation in hydrogen. The receiving system consists of a large diameter telescope tailored with a signal detection and data acquisition/processing system with 5 ns–10.5 ms multi-channel scaler/averager. This paper deals with a brief description of the lidar system developed and discusses the methodology followed for the retrieval of ozone vertical distributions from the lidar back-scattered signals obtained at 'on' and 'off' wavelengths. These initial results are compared with those obtained from a collocated ozonesonde and multi-filter solar radiometer and also with coincident observations from TOMS satellite. They are found to be in fair agreement within the experimental limitations.