Some Characteristics of Background Aerosols Over the Pacific Ocean

Abstract

tion of large particles depended on the wind force and showed a pronounced peak around 0.4 * 10-4cm in radius.

The Effect of Continental Air Mass on the Modification of Individual Sea-Salt Particles Collected over the Coast and the Open Sea

“…400/cm3 are due to an influx of continental air so that the ratio of modified particles show scattered values. This threshold value is almost equal to the background concentration (Kojima and Sekikawa, 1974) and four thousandths of the continental value, ca. 100,000/cm3 in Tokyo in winter .…”

“…The aerosol particle concentration was continuously measured with a Pollak condensation nuclei counter (Pollak Counter), which determines the total number of particles larger than 0.001 µm (Kojima and Sekikawa, 1974). In continental air, the number of particles obtained by using this counter is practically identical with that smaller than 0.1µm in radius, because of the relatively small concentration of larger particles (Junge, 1963).…”

“…Several researchers (e.g., Misaki et al, 1975;Ito et al, 1986) investigated the life time of aerosol particles. Background aerosol was investigated by several researchers (e.g., Junge and Jaenicke, 1971;Kojima and Sekikawa, 1974;Parungo et al, 1986a). They observed anthropogenic air pollution from a continent over a remote ocean.…”

“…The degree of modification over the sea depends on the production rate of sea-salt particles and the amount of pollutant, for example SO2 or sulfate particles. The production rate and the size of sea-salt particles depend on the wind force (e.g., Kojima and Sekikawa, 1974) and the life time of sea-salt particles depends on their size. Tables 2 and 3 show no relationship between the degree of modification and the wind speed.…”

“…The transport period was obtained from the analyzed results of air mass trajectory. The isentropic backward-trajectory was originally calculated every 3 hr by using the daily standard pressure level data belonging to Long-Range Forecast Division, the Japan Meteorological Agency (Kumakura et al, 1990). For example, we show the trajectories at R5 and R9 in Figs.…”