Suggestion for qualitative lidar identification of different types of aerosol using the two-wavelength rotational Raman and elastic lidar

Abstract

Aerosols are important parameters in the meteorological and environmental fields, and remote aerosol identification is extremely desirable. We have proposed and designed a two-wavelength (355 and 532 nm) rotational Raman and elastic lidar that can measure the wavelength dependence of the aerosol backscattering coefficient without any assumptions about the Angström coefficient or the overlapping function from low (100 m) to high (10 km) altitude, depending on the weather conditions. We have measured the differences in the backscattering ratios (BRs) among a cloud, aerosol in the boundary layer, and Asian dust. The ratio of the aerosol backscattering coefficients between two wavelengths is a fingerprint of an aerosol, which is similar to the Angström coefficient. The BR value for a typical aerosol ranged from 0.56 to 0.4 in the boundary layer and from 0.5 to 0.1 for Asian dust. The BR value of water droplet was not unique but was spread over a wide range because of its size distributions.