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Sources of the seasonal-trend behaviour and periodicity modulation of 7Be air concentration in the atmospheric surface layer observed in southeastern Spain

Journal article
Authors E. Chham
A. Milena-Pérez
Francisco Piñero-García
M. A. Hernández-Ceballos
J. A. G. Orza
E. Brattich
T. El Bardouni
M. A. Ferro-García
Published in Atmospheric Environment
Pages 148-158
ISSN 1352-2310
Publication year 2019
Published at Institute of Clinical Sciences, Department of Radiation Physics
Pages 148-158
Language en
Keywords 7Be, Atmospheric aerosols, Teleconnections indices, Time series decomposition, Wavelet analysis, Atmospheric thermodynamics, Behavioral research, Clouds, Solar energy, Time series, Time series analysis, Wavelet decomposition, Wind, Atlantic multidecadal oscillations, Atmospheric parameters, Atmospheric surface layers, Continuous wavelet transforms, Quasi-biennial oscillation, Teleconnections, ^7Be, Atmospheric humidity, aerosol, Atlantic Multidecadal Oscillation, beryllium isotope, concentration (composition), periodicity, seasonality, solar activity, solar cycle, teleconnection, trend analysis, article, continuous wavelet transform, decomposition, humidity, modulation, oscillation, precipitation, Spain, sun, wind speed, Granada [Nicaragua], Nicaragua
Subject categories Meteorology and Atmospheric Sciences, Climate Research


The components and the periodicity characterising airborne 7Be monthly concentration collected in Granada (SE Spain) between 2000 and 2018 are studied. These 19 years of measurements are particularly significant for the 7Be analysis as they cover the complete 24th solar cycle, 2008–2018. A Time Series Decomposition (TSD) technique has been applied to determine the different components present in the dataset: the trend, seasonal and irregular components. Then, the atmospheric parameters (Precipitation (Pp), Relative Humidity (RH), Temperature (Temp), Wind speed (WS), Total Cloudiness (TC), Low Cloudiness (LC)), teleconnection indices and the solar activity (Sun Spot Number, SSN) were used to justify the variability of each component. SSN and the teleconnection indices (Western Mediterranean Oscillation (WeMO), Atlantic Multidecadal Oscillation (AMO) and Quasi Biennial Oscillation (QBO)) are found to have a major impact on the trend component of 7Be. In turn, all the atmospheric parameters were found to have strong impact on the seasonal component. In order to observe the change in the impact of the parameters from the 24th solar cycle (from 2008 to 2018) to the complete time series (starting in 2000), the comparison between the two periods has been carried out. The results show that, over the 24th solar cycle, the SSN impacted predominantly on the trend component, whereas atmospheric parameters showed a slightly higher impact on the seasonal component. In addition, some atmospheric factors (Temp, RH, Pp, TC, LC) appeared to partially affect the irregular component. The analysis of the two phases of the 24th solar cycle shows that the influence of SSN is higher during the descending phase than during the ascending one. This behaviour is opposed to the one found for the 23rd solar cycle, which clarifies the special characteristics of the 24th cycle. Besides that, the Continuous Wavelet Transform (CWT) analysis was applied in order to extract the possible periodicities characterising 7Be data. The analysis revealed three sets of periodicities. Then, the Wavelet Coherence Analysis (WCA) method was particularly useful to study coherences between 7Be data and teleconnection indices. The 7Be concentrations in the large period (11–14 years) detected by CWT was found to be mainly modulated by WeMO, AMO and QBO, while the NAO modulates the smaller periods. © 2019 Elsevier Ltd

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