Simulation of SPM Concentration Taking into Account the Effect of Liquid Water

Abstract

Simulation of SPM concentration was carried out with taking into account the effect of water, since the weight of SPM measured in an urban area appeared to be affected by liquid water through change of relative humidity of the air. As a diffusion model, so-called multi-box model was applied. Both of pseudo-diffusion arose from calculation scheme of the multi-box model and actual turbulent diffusion affect on the concentration. Thusthe correction of the pseudo-diffusion was discussed first, and a method to correct this effect was proposed. This correction method leads to reflecting actual turbulent diffusion, resultantly.
Effect of liquid water on the weight of particles in the air was estimated by simplified Winkler's⁸ empirical formula introduced for the description of characteristics of aerosol in an urban area. Calculation was made for 4 days, chosen from high concentration days in winter in Tokyo prefecture. With taking into account the effect of water, calculated concentration became closer to observed data in comparison with no water condition.