Abstract
We compared the periodic characteristics of the atmospheric radon concentration on the land and ocean, using data simultaneously measured at Oki Island in the Sea of Japan and Matsue, which is located 70km south of the island and on the Shimane peninsula. The radon concentration was the highest in the fall at Matsue and in the winter at Oki Island and the lowest during the summer at both locations. The frequency distributions and the annual periodic variations of the arriving pathways of the air masses and these radon concentrations at Matsue and Oki Island showed the same tendency. At Matsue, the monthly average of diurnal minimum of the radon concentration was highest in the winter that was three month late from the maximum season of the monthly average of all measurements. The monthly average of radon concentration at Matsue showed the positive correlation between the monthly occurrence times of temperature inversion. The annual periodic variation of the radon concentration at Oki Island depends on the long-term variation of the distribution of arriving pathways of the air masses.
