Laser Radar Application To Air Pollution Potential Measurements During Post-Sunset Period

Abstract

The ventilation coefficient which represents the rate at which air within the mixed layer is transported is an index of air pollution potential over a place. From the Argon ion lidar derived aerosol number density profile data obtained during the three-year period from October 1986 to September 1989 at the Indian Institute of Tropical Meteorology (11TM), Pune, mixing depths in the post-sunset period have been derived. These depths coupled with the pilot balloon wind data obtained from IMD, Pune on the days of lidar observations, ventilation coefficients have been computed. It is found that the coefficients are relatively higher in pre-monsoon months and lower in the south-west (SW) monsoon and winter months. The study suggests that late winter evening at Pune (urban station) tend to have higher pollution potential and the ventilation coefficients are minimum in the postmidnight period. Further, there seems to be no significant increasing or decreasing trend in the year-to year variation of ventilation coefficient over this station. The study emphasizes the importance of lidar for air quality measurements and pollution potential forecasts in urban regions in general and industrial regions in particular.