Kobayashi Yuka, Yasuoka Yumi, Omori Yasutaka, Nagahama Hiroyuki, Sanada Tetsuya, Muto Jun, Suzuki Toshiyuki, Homma Yoshimi, Ihara Hayato, Kubota Kazuhito, Mukai Takahiro
Kobe Pharmaceutical University, 4-19-1, Motoyamakitamachi, Higashinada-ku, Kobe City, Hyogo, 658-8558, Japan.
Kobe Pharmaceutical University, 4-19-1, Motoyamakitamachi, Higashinada-ku, Kobe City, Hyogo, 658-8558, Japan.
J Environ Radioact. 2015 Aug;146:110-8. doi: 10.1016/j.jenvrad.2015.04.007. Epub 2015 May 16.
Anomalous atmospheric variations in radon related to earthquakes have been observed in hourly exhaust-monitoring data from radioisotope institutes in Japan. The extraction of seismic anomalous radon variations would be greatly aided by understanding the normal pattern of variation in radon concentrations. Using atmospheric daily minimum radon concentration data from five sampling sites, we show that a sinusoidal regression curve can be fitted to the data. In addition, we identify areas where the atmospheric radon variation is significantly affected by the variation in atmospheric turbulence and the onshore-offshore pattern of Asian monsoons. Furthermore, by comparing the sinusoidal regression curve for the normal annual (seasonal) variations at the five sites to the sinusoidal regression curve for a previously published dataset of radon values at the five Japanese prefectures, we can estimate the normal annual variation pattern. By fitting sinusoidal regression curves to the previously published dataset containing sites in all Japanese prefectures, we find that 72% of the Japanese prefectures satisfy the requirements of the sinusoidal regression curve pattern. Using the normal annual variation pattern of atmospheric daily minimum radon concentration data, these prefectures are suitable areas for obtaining anomalous radon variations related to earthquakes.
在日本放射性同位素研究所的每小时排放监测数据中，已观测到与地震相关的氡的异常大气变化。了解氡浓度的正常变化模式将极大地有助于提取地震异常氡变化。利用来自五个采样点的大气每日最低氡浓度数据，我们表明可以将正弦回归曲线拟合到这些数据上。此外，我们确定了大气氡变化受大气湍流变化和亚洲季风的海陆模式显著影响的区域。此外，通过将五个站点正常年度（季节性）变化的正弦回归曲线与之前发表的日本五个县的氡值数据集的正弦回归曲线进行比较，我们可以估计正常年度变化模式。通过将正弦回归曲线拟合到包含日本所有县站点的先前发表的数据集中，我们发现72%的日本县满足正弦回归曲线模式的要求。利用大气每日最低氡浓度数据的正常年度变化模式，这些县是获取与地震相关的异常氡变化的合适区域。
