| Abstract : | To study the solar rotational oscillation during daily averaged time series of solar activity proxies: sunspot numbers, modified coronal index, solar flare index, and cosmic ray intensity are subjected to Lomb/Scargle periodogram, Robper periodogram, and continuous wavelet transform. All three spectral analysis techniques are carried out to study the behavior of 27-days and its time scale of the synodic period and to follow their evolution throughout the epoch 2012 to 2015. The correlation coefficients and time lags between the rotational periods of cosmic ray intensity and solar activity indicators are also presented. It is noted that the ~27-day period of solar activity parameters and cosmic ray is much prominent during the examined period, moreover, sunspot number, modified coronal index, and solar flare index are lagged by 161, 152, and 40 days respectively with the intensity of the cosmic rays during 2012-2014. |
