On the Spatial Distribution of Submicron Aerosols over the Izu Islands, Pacific Ocean

Abstract

Measurements on the total concentration and size distribution of submicron aerosols in the mixing layer were performed over the Izu Islands of Japan, during October to November 1981. The purpose of observations was to get informations about transport, transformation and removal processes of anthropogenic materials from land to ocean. Continuous records were obtained by using Eiectrical aerosol analyzer (EAA) and Light-scattering particle counter which, overlapping steps, covered a size range 0.003 to 10μm diameter.
Results of observations showed that there were differences in the fate and behavior of aerosols depending upon meteological conditions. In the case of quiet and settled weather condition such as anticyclone over the mainland of Japan, concentration of aerosols showed maximum value (10³cm^-3) near the coastal area of Sagami Bay and minimum value (10²cm^-3) near Hachijo Is. Their dilution facter associated with spatial dispersion was estimated the order of 10^-6 to 10^-5m^-1. In the case of westerly wind prevailing, concentration of aerosols was immediately increased and the wind analysis suggested that pollutants had been transported from Chukyo district. At the condition of stratocumulus precipitation with medium cloud base, concentration of aerosols was decreased and distribution curve was deformed from Junge's power law of average maritime component. The collection efficiency of submicron aerosols calculated from observational results was much higher than the value which recent theories predict. Some possible explanations of these discrepancies were also discussed.