REMOTE-SENSING OF ATMOSPHERIC AEROSOL IN THE NOCTURNAL BOUNDARY-LAYERUSING LIDAR

This paper presents the results of the lidar experiments that have bee n performed during January 1989 through August 1990 to study the aeros ol vertical distributions in the nocturnal atmosphere and their compar ison with near-simultaneous aerological soundings for environmental mo nitoring. During the study period, the aerosol distributions showed si gnificant stratified aerosol layer structures in the lower atmosphere throughout the south-west monsoon season (June-September), while these structures appear to be either erratic or absent during remaining mon ths of the year. In addition, the aerosols present in the lowest air l ayers up to 200 m are found to contribute significantly (about 40%) to the aerosol loading in the nocturnal boundary layer at the lidar site . The pre-monsoon to winter ratio of mixing depth and ventilation coef ficient were found to be 1.11 and 1.62, respectively. Thus the height of the mixed layer (around 350 m) and the associated ventilation coeff icients suggest that early winter evenings tend to have higher polluti on potential at the experimental site. The results indicate that the l idar technique has the potential to yield good information on the stru cture of the nocturnal atmosphere which is found to be influenced by t he atmospheric stability conditions as revealed by aerological observa tions.