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 (222Rn) and Thoron (220Rn) 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 220Rn and 222Rn 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 220Rn. The possible influence of meteorological factors on both 222Rn and 220Rn progenies atmospheric activity concentrations are discussed.

► Eighteen years of continuous observation of atmospheric Radon and Thoron. ► Dominant one year periodicity. ► Positive correlation with nocturnal temperature, negative with diurnal one. ► Negative correlation with precipitation level, temperature and sky cloudiness. ► Strong influence of the atmospheric turbidity.