Lidar Ratio–Depolarization Ratio Relations of Atmospheric Dust Aerosols: The Super‐Spheroid Model and High Spectral Resolution Lidar Observations
Senyi Kong, Kaori Sato, Lei Bi
Abstract
Abstract The backscattering optical properties of an ensemble of randomly oriented dust particles at a wavelength of 355 nm were comprehensively studied by examining the invariant imbedding T‐matrix results of the super‐spheroid dust model. In particular, we focused on the lidar ratio ( ) and depolarization ratio ( ) relations of dust aerosols to aid interpretation of data from the Atmospheric Lidar (ATLID) instrument that will be onboard the Earth Cloud, Aerosol and Radiation Explorer (EarthCARE) satellite. Super‐spheroid models with various aspect ratios ( ), roundness parameters , and refractive indices were investigated over a wide range of particle sizes and compared to the observation data of the National Aeronautics and Space Administration (NASA) Langley 355‐nm airborne high spectral resolution lidar. We found that super‐spheroid dust particles with different sets of and could be used to model almost the entire range of the observed joint distributions of and . The relation could effectively discriminate among dust particle types. The observed and values with the largest population density were best covered by models with n > 2, especially by those with varying from 2.4 to 3.0.