The European Physical Journal Special Topics

, Volume 224, Issue 4, pp 741–762

Intrinsic vs. spurious long-range memory in high-frequency records of environmental radioactivity

Critical re-assessment and application to indoor 222Rn concentrations from Coimbra, Portugal
  • R.V. Donner
  • S.M. Potirakis
  • S.M. Barbosa
  • J.A.O. Matos
  • A.J.S.C. Pereira
  • L.J.P.F. Neves
Regular Article

DOI: 10.1140/epjst/e2015-02404-1

Cite this article as:
Donner, R., Potirakis, S., Barbosa, S. et al. Eur. Phys. J. Spec. Top. (2015) 224: 741. doi:10.1140/epjst/e2015-02404-1
Part of the following topical collections:
  1. Radon Applications in Geosciences - Progress & Perspectives

Abstract

The presence or absence of long-range correlations in the environmental radioactivity fluctuations has recently attracted considerable interest. Among a multiplicity of practically relevant applications, identifying and disentangling the environmental factors controlling the variable concentrations of the radioactive noble gas radon is important for estimating its effect on human health and the efficiency of possible measures for reducing the corresponding exposition. In this work, we present a critical re-assessment of a multiplicity of complementary methods that have been previously applied for evaluating the presence of long-range correlations and fractal scaling in environmental radon variations with a particular focus on the specific properties of the underlying time series. As an illustrative case study, we subsequently re-analyze two high-frequency records of indoor radon concentrations from Coimbra, Portugal, each of which spans several weeks of continuous measurements at a high temporal resolution of five minutes.Our results reveal that at the study site, radon concentrations exhibit complex multi-scale dynamics with qualitatively different properties at different time-scales: (i) essentially white noise in the high-frequency part (up to time-scales of about one hour), (ii) spurious indications of a non-stationary, apparently long-range correlated process (at time scales between some hours and one day) arising from marked periodic components, and (iii) low-frequency variability indicating a true long-range dependent process. In the presence of such multi-scale variability, common estimators of long-range memory in time series are prone to fail if applied to the raw data without previous separation of time-scales with qualitatively different dynamics.

Copyright information

© EDP Sciences and Springer 2015

Authors and Affiliations

  • R.V. Donner
    • 1
  • S.M. Potirakis
    • 2
  • S.M. Barbosa
    • 3
    • 4
  • J.A.O. Matos
    • 5
  • A.J.S.C. Pereira
    • 6
  • L.J.P.F. Neves
    • 6
  1. 1.Research Domain IV – Transdisciplinary Concepts & Methods, Potsdam Institute for Climate Impact ResearchPotsdamGermany
  2. 2.Department of Electronics EngineeringPiraeus University of Applied SciencesAthensGreece
  3. 3.INESC TEC – INESC Technology and SciencePortoPortugal
  4. 4.Instituto Dom Luiz, University of LisbonLisbonPortugal
  5. 5.Faculty of Economics, University of PortoPortoPortugal
  6. 6.CEMUC – Department of Earth Sciences, University of CoimbraCoimbraPortugal

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