SCATTERING ANGLE DISTRIBUTION OF LASER-RETURN SIGNAL STRENGTH IN THE LOWER ATMOSPHERE

The bistatic, continuous wave Argon ion lidar system developed at the Indian Institute of Tropical Meteorology, Pune, India has been used to examine the nature of variation of laser-return signal strength (from a constant altitude in the lower atmosphere) with scattering angle (v aried from 90 to 175 degrees). The observed variation correlates well with the calculated variation in Mie scattering cross section assuming a power law type particle size distribution. The values of size index and real part of refractive index at the observation site are found t o be around 4.6 and 1.53, respectively. Results suggest The presence o f water-soluble, dust-like aerosols with predominance of larger sized particles during the premonsoon (March-May) and SW monsoon (June-Septe mber) seasons in the lower atmosphere at the lidar site.