Atmospheric aerosol–cloud-stability relationship as observed with optical and radio remote sensing techniques

Atmospheric aerosol characteristics are being monitored, on a routine basis, with lidars and spectroradiometer since 1985 and 1992, respectively, at the Indian Institute of Tropical Meteorology, Pune (18°32′N, 73°51′E, 559 m AMSL), a tropical Indian urban station. The lidar-derived nocturnal atmospheric structures, transport of surface-generated aerosols (pollutants) and their participation in the formation of clouds and their time evolution in the planetary boundary layer (PBL) are studied in relation to the local diabatic conditions and height-integrated relative humidity (RH) inferred from radiometersonde and pilot balloon (pibal) observations. This paper mainly addresses (i) how the integrated lidar, spectroradiometer and coincident aerometric data can be used to delineate the atmospheric structure and transport mechanisms, and (ii) the extent to which the lidar observations during different atmospheric conditions can be useful to explain the phenomenon of cloud scavenging of aerosols over the experimental station.