The Variation of Atmospheric ²²²Rn Concentration in Kobe

Abstract

The characteristic peaks of 1 day period and 1 year period were obtained through the Fourier analysis of atmospheric ²²²Rn concentration in Kobe. The ²²²Rn concentration showed the diurnal variation and seasonal variation.
The inverse relationship between the diurnal variation of the relative concentration of ²²²Rn and atmospheric temperature was obtained, because the ²²²Rn concentration at ground level in Kobe is affected strongly by the mixing of atmosphere. The representative times were approximately 9: 00 and 19: 00.
The seasons which the highest and lowest concentration occurred in Kobe were winter and summer, respectively. The seasonal variation depended only on the contribution of the distant component. The highest ²²²Rn concentration in Kobe was observed in winter, because the seasonal wind transports the air masses including high ²²²Rn concentration.