Tropospheric aerosol optical properties derived from lidar, sun photometer, and optical particle counter measurements

Tropospheric aerosols have been observed for the period from November 1990 to April 1992 with a lidar, a sun photometer, and an optical particle counter. Variations of aerosol optical thickness derived from the lidar and the sun photometer data and measurements are presented. The simultaneous measurements of these instruments also allowed us to estimate the extinction-to-backscatter ratio (S1), which ranged from 20 to 70. Comparison of optical thicknesses derived from both instruments clearly shows the effect of Mt. Pinatubo's eruption and the temporal variation of optical thickness in the stratosphere over 12 km. The possible range of the complex refractive index for the columnar mean aerosols can be deduced from the probable range of Si derived by the use of an S1 diagram as a function of complex refractive index (m). The imaginary part of m can be estimated provided that the real part of m is known.