Angstrom coefficient of tropospheric cloud and aerosol derived from a three-wavelength Mie lidar system

Clouds and aerosols play an important role on the Earth's radiation budget. One of the optical properties of clouds and aerosols that are needed for radiative transfer calculations is the volume extinction coefficient. This can be retrieved from the LIDAR return signal through an inversion method. The Angstrom coefficient,/spl delta/, which expresses the wavelength dependence of the extinction coefficient is then derived on the assumption of the Angstrom relation. The obtained values /spl delta/ can be used in principle to discriminate between different aerosol types, evaluate the particle size, and determine the size distribution of the particle. In this paper, the data obtained from the three-wavelength LIDAR system and initial results of the extinction coefficients of clouds and aerosols, and its wavelength dependence will be presented. In the manner similar to Grant el al, the difference in the values of the Angstrom coefficient between low-lying aerosols and low-altitude clouds provide a way of discriminating between clouds and aerosol particles.