1992 年 41 巻 2 号 p. 79-82
Space series analysis was made for 12 sets of equal interval data of terrestrial gammaray dose rate collected in the Japanese Islands, North America and Iceland. Each power spectral density (PSD) could be approximated in the form of P (k) =a·k-n, where P and k were the PSD and wave number, respectively, and a and n were a constant. The value of n ranged from around 1 to 1.7 and the average amounted to 1.3 for a wave-number region of 10-4 -103 cycles/km. The PSDs were divided into two groups having an average of a of 0.1 for Iceland data and that of 5.6 (nGy/h) 2⋅km for others.