Dynamical behavior of various periodicities observed in the northern hemisphere using wavelet power spectra for the monthly sunspot number time series data obtained from the model with fluctuations in all the parameters of the Babcock–Leighton process with a tilt scatter of σ_δ = 15°. Panel (a): Morlet wavelet spectra used to identify short-term periods (Rieger-type). Panel (b) Global power spectra for short-term periods (Rieger-type). The dotted red line represents a 95% confidence level. Panel (c): Similar to panel (a), but for the QBOs and long-range periods including the cycle corresponding to the 11 year solar cycle. Panel (d): Similar to panel (b), but for the study of QBOs and long periods.