The transport of particulate and gaseous matters in chamber flow ranging from laminar to turbulent flows was studied. Tracer particles and gas, monodisperse latex aerosol particles of 0.3 μm in diameter and oxygen gas, were passed through a 12 l cylindrical chamber to measure the temporal change in their concentration at the outlet port of the chamber. The temporal change was also investigated by numerically solving the governing equations for gas flow and the convective-diffusive transport of the particles and oxygen gas in the flow. When the flow in the chamber was considered to be laminar flow and sufficiently developed turbulent flow, the measured concentration changes were predicted quantitatively by employing the equations for laminar flow and those including one of the two versions of the k-ε turbulence model employed here, respectively. However, in the case that the flow was considered to be transitional flow, the results calculated using the high-Reynolds number version of the turbulence model (the standard k-ε model) overestimated the turbulent diffusive transport in the chamber. The other model, the RNG k-ε turbulence model, gave fairly a reasonable prediction for the transitional flow cases.
Intensive observations on chemical species in aerosol, gases, fog and precipitation at the summit of Mt. Fuji and at Tarobo (at 1,300 m above sea level on the mountain's southern slope) was performed from July 25 to 30, 1994, and compared with those from July 28 to August 3, 1993. In the 1993 campaign, the most interesting phenomenon was the abrupt increase in the nss-sulfate concentration in aerosol which was observed just after the typhoon (number 9306) passed the Japanese archipelago and the wind direction shifted from south to west. Chemical analysis indicated this aerosols was partly acidic. In the 1994 campaign, however, the summit aerosol was not acidic following a less dramatic rise in sulfate content. Size distribution study of chemical species in these aerosol indicated that sulfate and ammonium ions in the aerosol obtained in the 1993 campaign showed unimodal pattern, while those obtained in 1994 showed bimodal pattern. Back trajectory analyses were used to extrapolate the movement of air mass which arrived at the summit. In the 1993 campaign, polluted air over the Asian Continent was suspected to be transported long way from the west, but in the 1994 campaign, most of the polluted air was supposed to come from the Kanto area, Japan. Additional information from, 7Be study in 1994 aerosol suggests a transportation of upper air to the summit at the same time.
Tropospheric and stratospheric aerosol particle size, number density, and morphological feature were observed in August, 1993 at Beijing, China (40°N, 116°E). Irregular shape particles, possibly soil particles, were frequently observed in the free troposphere on the basis of scanning electron microscopic measurements of individual particles collected on the surface of carbon-coated nitrocellulose (collodion) films with a balloon-borne particle counter. In the stratosphere the particles with ‘satellite structure’ which has been recognized as a typical feature of sulfuric acid droplets on carbon deposited surface were major particles. Ammonium sulfate particles were frequently identified in the mid troposphere. The number density of the particles with their diameter, d, larger than 0.4 μm was about 3 particles/cm3 near the density peak of the stratospheric aerosol layer, suggesting that the disturbance due to the volcanic eruption of Mt. Pinatubo (1991; Philippine) remained in the stratosphere. Less uniformity in number density profiles of the particles with d ≥ 0.4 μm was observed in the troposphere, suggesting the effect of dynamical air motions with various spacial scales over the Asian continent in summer on aerosol density distributions.