Vertical distribution and optical properties of aerosols observed over Japan during the Atmospheric Brown Clouds–East Asia Regional Experiment 2005

Abstract

Lidar and sky radiometer systems at Sapporo, Toyama, and Nagasaki, Japan, observed the vertical distributions and optical properties of (nonspherical) dust and spherical aerosol particles from March to May 2005 as part of the Atmospheric Brown Clouds–East Asia Regional Experiment 2005 (ABC‐EAREX2005). Sky radiometer observations suggest that single scattering albedo at Nagasaki was smaller than that at Toyama and Sapporo. Relationships between the single scattering albedo and Ångstrom exponent suggest that aerosol particles observed at Toyama in March differed from those observed in April and May. In contrast, at Nagasaki, there was no obvious difference in aerosol particles among the 3 months. Aerosol optical thicknesses observed by the sky radiometer resemble the aerosol optical thicknesses observed by lidar and simulated by the Chemical Weather Forecasting System (CFORS) model. A new parameter that describes the aerosol vertical distribution, Hm, is the modified scale height of the extinction coefficient. Hm can be used as an index of the vertical aerosol extent even if the detailed structure of the vertical profile cannot be shown. Hm observed by lidar was consistent with Hm simulated by the CFORS. Relationships between the aerosol optical thickness and Hm obtained by lidar measurements and CFORS simulations suggest that dust aerosol particles are generally transported over Japan at higher altitudes than are spherical aerosol particles.