E cyclical component, because of the fact that the analysed periods of time are lower than a year, can be studied, and also the autocorrelation total and partial would be the tools for this study. For the autocorrelations, the delay is indicated around the X-axis, and the correlation value is indicated on the Y-axis (among -1 and 1). Both correlations show a specific correlation in between the observed values (represented in blue)having a time delay of k = 52 weeks, which allows us to affirm the presence of a seasonal component in the time series (Ibuprofen alcohol Epigenetic Reader Domain Figure 5).six ofAtmosphere 2021, 12, x FOR PEER REVIEW7 ofThe existence of this dominant seasonal and cyclical behaviour in Bilbao is statistically justified by the periodogram calculated and shown in Figure six. The X-axis represents frequency, plus the Y-axis represents the spectrum. When the initial peak represents a oneyear period beta activity concentration activity (frequency 1.93 10-2 week-1, i.e., 52 weeks), the second peak (frequencies three.9 10-2 week-1, i.e., 25 weeks) may be the a single representing the intra-annual variability. Additionally, the Grubbs test was employed to study the existence of Figure 5. (a) Total autocorrelation and (b) partial autocorrelation of beta activity activity concentraFigure five. outliers autocorrelation and (b) partial autocorrelation of weeklyweekly beta concentra- inside the pre(a) Total amongst the registered values and concluded that there have been no outliers tions over the period 2014018 in Bilbao. The correlation lines are represented in black as well as the tions over theset of data becausein Bilbao.G-critcorrelation lines are represented in black along with the sent period 2014018 in blue. The using a 99 Cephapirin Benzathine Formula confidence interval around the p-value. G-crit correlation values for the delays are correlation values for the delays are in blue. elements of the alpha activity concentration identiThese results agree with all the fied and analyzed in preceding research at the similar web site [16]. In this sense, a constructive correThe existence of this dominant seasonal andwas identified, which is usually explained by the prinlation among alpha and gross beta (0.67) cyclical behaviour in Bilbao is statistically justifiedcipalthe periodogram calculated and shown in Figure six. The X-axis being precisely the same by supply term of each the airborne alpha and gross beta concentration represents frequency,normal situations.represents the spectrum. ratio was calculated for every week. The in plus the Y-axis Additionally, the alpha/beta Whilst the first peak represents a – -1 one-year periodwas 0.138, that is close for the standard ratio of 0.11.93as nicely 2as to otheri.e., average beta activity concentration activity (frequency [3] 10 week , values -2 week-1 , i.e., 25 weeks) could be the a single 52 weeks), the second peak (frequencies 3.9 10 obtained in Spain (0.14 in Salamanca (west) [11]; 0.1 in Malaga (south) [9]; 0.two in the CarepresentingIslands (south) [13]; and close to 0.1 in Valencia Grubbs test was employed to study the nary the intra-annual variability. Furthermore, the (east) [8]). Nevertheless, in spite of the existence of the 7Be values show seasonality and annual periodicity, the correlation with the fact that outliers among the registered values and concluded that there have been no outliers beta activity values is negligible, with acorrelation value99 confidenceis related around the within the present set of information mainly because G-crit G-crit with a of 0.16, which interval to value the p-value. obtained in the Canary Islands (0.16) [13].Figure 6.Figure six. Periodogram of weekly beta activity.
