Abstract
Atmospheric turbidity coefficients were calculated at five sites (Nemuro, Sapporo, Shionomisaki, Tosa-Shimizu and Ishigaki) in Japanese area from 1980 through 1992. The turbidity coefficients ranged 0.03-0.30 at Nemuro, 0.05-0.40 at Sapporo, 0.05-0.45 at Shionomisaki, 0.03-0.40 at Tosa-Shimizu and 0.03-0.40 at Ishigaki. They decreased in autumn and winter, and increased in spring. Variations of the turbidity coefficients had tendency of increase from 1957 through 1992 due to increase of human activities. In 1982-1984 and after 1992, the turbidity coefficients had the maximum due to large volcanic eruptions of Mt. El Chichon and Mt. Pinatubo, respectively.
