On the Number Size Distribution of Aitken Particles in the Urban Atmosphere

Abstract

Collections of aerosol particles were carried out with an electrostatic aerosol sampler in the summertime at Nagoya and Yokkaichi which are heavily polluted areas in Japan. By electron microscopic examination 21 number size distributions of all particles and those of sulfate particles, including those in the Aitken size range, were obtained. Method for the detection of sulfate ions by electron microscopy, proposed by Bigg et al. (1974), was applied to the individual particles. Sulfate particles were found to be predominant in the range of 0.016 to 0.28*m radius and they were detected with high number fractions of particles, 55 to 75* on the average. It is considered that the distributions of aerosol particles in the Aitken size range were closely related to the behavior of sulfate particles formed by gas-to-particle conversion influenced by the amount of pre-existing particles.

Nature of Individual Hygroscopic Particles in the Urban Atmosphere

“…Okada et al (1983) pointed out that Aitken particles in the urban atmosphere had some types of number size distribution in the daytime in association with the formation process of particles by gasto-particle conversion. In order to obtain the knowledge of the nature of hygroscopic particles in relation to the formation and modification processes, the collections of particles were carried out mostly in the daytime (noon).…”

Note on the Effect of Number Concentration of CCN on the Number Concentration of Cloud Droplets

“…But in the case of low concentration of CCN, the difference between dotted line and solid line is recognized clearly at large ascending velocity. If the number concentration of CCN is modified in broader radius range (ex, less than 0.08 *m as observed by Okada et al (1983)), this difference becomes larger. Figure 3 indicates that such a modification of the size distribution of small CCN as shown by dotted lines in Fig.…”

“…Small CON can affect the cloud droplet number concentration only in the case in which small CON can be activated. Okada et al (1983) found the size distribution of aerosols in which the number concentration of small aerosols (expressed by dN/dlogr) does not increase with decreasing radius in the radius range smaller than 0.08 *m.…”

“…Okada et al, 1983) that the size distribution of small aerosol particles can not be approximated by the same straight line as the size distribution of large aerosol particles in a logarithmical scale. In this paper, especialy, the effect of the size distribution of small CCN on droplet number concentration will be discussed.…”

Determination of the concentration of chemical main and trace elements (chemical matrix) in the aerosol from 1972 to 1982 at a North-alpine pure air station at 1780 m a.s.l.

“…Furthermore station Wank is not fully open to free geostrophic flow. Consequently, SOs contributes also to cloud (fog) formation and -stabilization (see also [8]). We, therefore, used in addition wind direction values from the neighboring station Zugspitze (2964 m a.s.1.)…”