Comparison of aerosol vertical profiles derived by passive and active remote sensing techniques—a case study

Simultaneous observations were carried out with twilight photometer and lidar at the National MST Radar Facility (NMRF), Gadanki (13.45°N, 79.18°E) during March 2003, in order to validate the photometer derived profiles, especially the relative heights of the observed dust layers. The aerosol vertical profiles retrieved by both the techniques were compared. The comparison was found to be qualitative. The results showed that the screening height (correction factor to the geometrical Earth's shadow height) for twilight technique was about 6 km for red light, below which no direct information on atmospheric aerosols can be obtained. The results evidenced the presence of high cirrus cloud with base height ranging from 11 to 14 km and stratospheric aerosol layer, or Junge layer (17–23 km), in the profiles derived by both the techniques.