Red Shift Phenomena revealed in the Zonal Winds Oscillations Probably Induced by the Sunspot Cycle

By inter-comparing exhaustively the results of wavelet analysis of the sunspot cycles and apparently associated oscillations in the time series of the zonal winds over the tropics, we found convincing evidences of the frequency shift of the oscillations, especially in the lower troposphere. The frequency of the oscillations forced by sunspot cycle decreased considerably in the lower troposphere, which is an analogue of the gravitational red shift or the doppler red shift even though their mechanisms are obviously different for each shift. The red shift revealed in our analysis may be explained with the framework of a damped harmonic oscillator forced by the oscillatory forcing due to the variation of sunspot number in time. However, the forcing is not so strong or effective that it could not drive continuously the observed oscillations in the atmosphere. By examining the frequency change of a sinusoid which has been modulated in frequency, we showed a probable functioning of red shift in the time series of the sunspot-induced oscillations in the lower troposphere. The implications of our finding of the ‘red shift’ phenomenon are fundamental for investigating and understanding of the atmospheric wave phenomena and their possible connections to the remote forcing and/or the induced motions in distant place of the atmosphere. The conventional analysis method using the coefficients of correlation or their sophisticated derivatives would be very sensitive to the data time period in investigating any connections between the oscillations manifesting frequency shift. The value of the correlations between the oscillations involved in frequency modulation will go to zero in general when increasing the data period for analysis, as evident from the coefficient of correlation between the two sinusoids with different periodicity.