Retrieval of microphysical properties of dust aerosols from extinction, backscattering and depolarization lidar measurements using various particle scattering models

Abstract

Mineral dust is a key atmospheric aerosol agent that impacts the radiation budget and plays a significant role in cloud formation. However, studies on retrieving height-resolved microphysical properties of dust aerosols, which are crucial for understanding dust evolution, transport processes, and radiative effects, from lidar measurements are still insufficient. Here, we retrieve dust aerosol microphysical properties, including the volume size distribution (VSD), total volume concentration (Vt), effective radius (reff), complex refractive index (CRI), and single-scattering albedo (SSA), from spectral extinction ( α), backscattering ( β), and depolarization (δ) lidar measurements. We evaluate the performance of three particle scattering models, namely the spherical, spheroidal, and irregular-hexahedral (IH) models, in terms of mimicking dust optical properties and deriving retrieval results when different measurement combinations are inverted. Both simulations and inversions of real lidar measurements confirm the superiority of the IH model and the significance of spectral depolarization measurements to improve the retrieval accuracy. An increase in discrepancy in depolarization ratio produced by the IH and spheroid models is observed for reff>0.5 μm, resulting in larger retrieval difference between the two non-spherical models after the inclusion of 3δ. Comparisons of the real case retrievals with Aerosol Robotic Network (AERONET) retrievals and previous in situ results indicate relatively smaller reff and larger SSA derived from the lidar retrievals. A discussion of the possible reasons is presented.