Aerosol optical and microphysical properties as derived from collocated measurements using polarization lidar and direct sampling

Collocated and simultaneous measurements of aerosols near the ground were conducted using a lidar and aerosol sampler at Tsukuba, Japan, to clarify the relationship between lidar-derived optical properties and in-situ microphysical properties. The total linear particle depolarization ratio (δp) ranged from 14% to 18% when nonspherical mineral dust particles were predominant in the supermicrometer range on May 7–8, 2008, whereas it ranged from 6% to 7% when spherical sea-salt particles were predominant in that range on September 3–4, 2008. Sulfates and nitrates were predominant in the submicrometer range for these two periods. Water-dialysis analysis on May 6–7 indicated that 29% of the coarse particles were water insoluble, whereas 70% were water soluble or nearly soluble on September 3–4. The ratio of dry mass concentration to the backscattering coefficient (M/βp) was 34–39 g m−2 sr on May 7–8 and 6.2–6.3 g m−2 sr on September 3–4. Our results provide evidence that lidar-derived βp and δp capture the aerosol mass concentration and relative abundance of the spherical and nonspherical particles although the microphysical properties vary significantly for individual particles.