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

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