## 4 Discussion
This shows that the non-migrating tides could have been produced by the basic physical processes considered by the classical tidal theory. At a higher altitude of 0.0007 hPa (Figure 7), SPW1 amplitudes reduce and show peaks with amplitudes of 4-5 K over the winter high latitudes and over the equator the amplitudes are in the range of 2-3 K. Simultaneously, DS0 and DW2 tides show maxima with amplitudes of 4-5 K during boreal summer and winter, respectively. Additionally, the variability of DS0 is weaker and distorted during winters, while that of DW2 during summers is almost negligible. For bothtides, the band over the equator is strongest. All amplitudes show significant short-term variabilities of the order of a month. We perform a wavelet analysis using CWT with a Morlet wavelet of degree 6, i.e., \(\omega_{0}=6\)[44], to investigate these variabilities among the different waves. Figure 9 shows the wavelet power spectrum of the average amplitude of DW2 over \(\pm 20^{\circ}\) at (a) 0.0007 hPa, (b) 1 hPa, and (c) 10 hPa, along with (d) that of SPW1 amplitude over \(65^{\circ}\) at 10 hPa from CMAM30 temperature data. The black contours show the wavelet power at a confidence level of 99% with respect to a white noise background [44]. In all panels, the periods at 50 and 100 days are highlighted using horizontal dashed lines to aid the eye. The SPW1 amplitude in the high-latitude stratosphere shows significant variabilities during boreal winters at periods of 70 days in 2006-2007, 100 days in 2007-2008, 60 days in 2008-2009, and 70 days in 2009-2010. Apart from these, there is a prominent annual variation, which is expected due to the high amplitudes observed every winter. Amplitudes of DW2 over the  
Figure 8: Latitude versus time variation of amplitudes of DS0, DW2, and SPW1 tide at 0.0007 hPa (\(\sim\)95 km, in the **top** three panels) and 2 hPa (\(\sim\)40 km, in the **bottom** three panels) from CMAM30 temperature data. equatorial region, particularly in the higher altitudes, show similar periods during boreal winters and at other times, and there is no correlation with SPW1 variability. At 10 hPa, a weak semi-annual variation and a strong annual variation are observed. Our interest is in periods less than 100 days. A small island of statistically significant power is seen in January 2007 at 30 days. Periods of 70-80 days are observed from mid-2007 to mid-2008, and those from 50 to 100 days are observed during the winter of 2008-2009. More small islands are seen at 50 days in September-October of 2008 and 40 days in November-December 2009. During the winter of 2009-2010, 100-day variability is also seen. At 1 hPa, a 50-day variation is seen from mid-2006 to almost the end of 2007, followed by 100-day variability from September-October of 2008 to September-October of 2009, and a 50-day period is once again indicated during the winter of 2009-2010. Further up at 0.0007 hPa (\(\sim\)95 km), the situation is more complex, with dominant periods increasing from 50 days to 100 days from mid-2006 to mid-2008. From mid-2008 onwards, the semi-annual and \(\sim\)70 days become prominent. Early 2010 also sees a \(\sim\)70-day period. Comparison between high-latitude stratospheric SPW1 amplitudes and high-latitude equatorial DW2 amplitudes shows that similar periods exist in both these waves, mostly during boreal winters, and there is no similarity during other epochs. Figure 9: Wavelet power spectrum of average amplitude of DW2 over \(\pm\)20\({}^{\circ}\) at **(a)** 0.0007 hPa, **(b)** 1 hPa and **(c)** 10 hPa, **(d)** wavelet power spectrum of SPW1 amplitude over 65\({}^{\circ}\) N at 10 hPa extracted from CMAM30 temperature data. Similar analysis is also performed for the amplitude of DS0. Figure 10 shows the wavelet power spectrum of the average amplitude of DS0 over \(\pm 20^{\circ}\) at (a) 0.0007 hPa, (b) 1 hPa, and (c) 10 hPa, along with (d) that of the SPW1 amplitude over 65\({}^{\circ}\) N at 10 hPa from CMAM30 temperature data (similar to last panel in Figure 9).