Eighteen years of continuous observation of Radon and Thoron progenies atmospheric activity

The eighteen years (1993-2010) of continuous observations of the activity concentrations of Radon (Rn-222), and Thoron (Rn-220) progenies within the atmosphere as recorded twice a day in Arad (Romania) are analyzed and discussed in correlation with air temperature, monthly precipitation and sky cloudiness. A detailed statistic analysis of all data revealed more peculiarities such as a systematically higher concentration in the morning compared to midday, a negative correlation between Rn-220 and Rn-222 activity concentrations and precipitation level, temperature and sky cloudiness. Both Morlet wavelet and power spectra confirmed the predominance of the one year periodicity, as well as the presence of some components with a periodicity of 7.2, 2.8, 1.5 and 1.2 years, more evident in the case of Rn-220. The possible influence of meteorological factors on both Rn-222 and Rn-220 progenies atmospheric activity concentrations are discussed. (C) 2011 Elsevier Ltd. All rights reserved.