title: Application of spectral decomposition of ²²²Rn activity concentration signal series measured in Niedźwiedzia Cave to identification of mechanisms responsible for different time-period variations.
abstract: The authors present an application of spectral decomposition of (222)Rn activity concentration signal series as a mathematical tool used for distinguishing processes determining temporal changes of radon concentration in cave air. The authors demonstrate that decomposition of monitored signal such as (222)Rn activity concentration in cave air facilitates characterizing the processes affecting changes in the measured concentration of this gas. Thanks to this, one can better correlate and characterize the influence of various processes on radon behaviour in cave air. Distinguishing and characterising these processes enables the understanding of radon behaviour in cave environment and it may also enable and facilitate using radon as a precursor of geodynamic phenomena in the lithosphere. Thanks to the conducted analyses, the authors confirmed the unquestionable influence of convective air exchange between the cave and the atmosphere on seasonal and short-term (diurnal) changes in (222)Rn activity concentration in cave air. Thanks to the applied methodology of signal analysis and decomposition, the authors also identified a third process affecting (222)Rn activity concentration changes in cave air. This is a deterministic process causing changes in radon concentration, with a distribution different from the Gaussian one. The authors consider these changes to be the effect of turbulent air movements caused by the movement of visitors in caves. This movement is heterogeneous in terms of the number of visitors per group and the number of groups visiting a cave per day and per year. Such a process perfectly elucidates the observed character of the registered changes in (222)Rn activity concentration in one of the decomposed components of the analysed signal. The obtained results encourage further research into precise relationships between the registered (222)Rn activity concentration changes and factors causing them, as well as into using radon as a precursor of geodynamic phenomena in the lithosphere.
authors.affiliation: Wrocław University of Technology, Faculty of Geoengineering, Mining and Geology, Institute of Mining Engineering; Wybrzeże S. Wyspiańskiego 27; 50-370 Wrocław, Poland. Electronic address: Tadeusz.Przylibski@pwr.edu.pl.
authors.forename: Tadeusz Andrzej
authors.initials: TA
authors.lastname: Przylibski
authors.affiliation: Wrocław University of Technology, Faculty of Fundamental Problems of Technology, Hugo Steinhaus Center; Wybrzeże S. Wyspiańskiego 27; 50-370 Wrocław, Poland. Electronic address: Agnieszka.Wylomanska@pwr.edu.pl.
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Wyłomańska
authors.affiliation: Wrocław University of Technology, Faculty of Geoengineering, Mining and Geology, Institute of Mining Engineering; Wybrzeże S. Wyspiańskiego 27; 50-370 Wrocław, Poland. Electronic address: Radoslaw.Zimroz@pwr.edu.pl.
authors.forename: Radosław
authors.initials: R
authors.lastname: Zimroz
authors.affiliation: Wrocław University of Technology, Faculty of Civil Engineering, Institute of Geotechnics and Hydrotechnics; Wybrzeże S. Wyspiańskiego 27; 50-370 Wrocław, Poland. Electronic address: Lidia.Fijalkowska-Lichwa@pwr.edu.pl.
authors.forename: Lidia
authors.initials: L
authors.lastname: Fijałkowska-Lichwa
keywords: Cave; Continuous measurement; Modelling; Radon; Statistical analysis; Time series segmentation