## 4 Discussion  
It is very difficult to extract all tidal features from satellite measurements with accuracy and no aliasing due to the asynoptic nature of measurements, particularly over mid and high-latitudes. Hence, simultaneous investigations of models is essential to correctly determine the tidal characteristics. The current study aimed to extract the short-term tidal variability along with an attempt to avoid aliasing by using multiple datasets from satellite, model, and reanalysis. The non-migrating tidal variability in the stratosphere from CMAM30 and ERA seen in the current study matches very well both in terms of amplitude and phase. Variability in COSMIC, however, differs, particularly in the high latitudes. These regions are significantly affected by aliasing problems in the analysis of satellite datasets [13; 14; 20; 30]. [PERSON] et al. [14] showed that using a shorter time window length using COSMIC data, the aliasing is significantly reduced, but still exists. The non-migrating tides, DS0 and DW2, are particularly affected by the non-stationarity in the amplitude of SPW1. [PERSON] [37] showed that SPW1 amplitudes in SABER and COSMIC temperatures show a variability of 30 to 120 days in the high-latitude stratosphere. The smaller period variabilities were seen in COSMIC using a window size of 21 days and thus clearly indicate that SPW1 is non-stationary. Thereby, it can impact the accurate deduction of DS0 and DW2 variabilities. It is thereby concluded that there is high probability that the high DS0 and DW2 amplitudes observed in the high-latitude stratosphere in COSMIC could be due to aliasing. This argument is further strengthened by the results from CMAM30 and ERA that do not suffer from aliasing problems and do not show any significant DS0 and DW2 amplitudes in the high-latitude stratosphere. Many studies showed that the non-migrating tides, DS0 and DW2, can be generated in the middle atmosphere via non-linear interactions between DW1 and SPW1 [24; 30]. However, the amplitudes of DS0 and DW2 deduced from SABER/TIMED are highly overestimated [24], largely owing to aliasing issues [14; 20]. These latter studies established significant doubt on the process of generation of DS0 and DW2 via non-linear interactions, as such large amplitudes or variabilities are not observed in the current study using CMAM30 or ERA data. In another study by [PERSON] [35] using SABER/TIMED data, DW2 variability in the MLT region over the equator was found to be very similar to that of SPW1 over the high-latitude stratosphere. It was inferred that the high-latitude SPW1 in the stratosphere propagates upward and equator-ward, where it interacts non-linearly with the DW1 tide and generates DW2. DS0 was not observed. In the current study, DS0 and DW2 variabilities are investigated using CMAM30 data to identify similarities with that of SPW1 (ERA and COSMIC data are not available in the MLT region and hence not investigated further). Figure 8 shows the latitude-time variabilities of amplitudes of DS0, DW2, and SPW1 at 0.0007 hPa (in the top three panels) and 2 hPa (in the bottom three panels), respectively, from CMAM30 data using a 21-day window. DS0 and DW2 amplitudes at 2 hPa are slightly larger and shifted northward in comparison to those seen at 10 hPa in Figure 7. The central band of DS0 over the equator dominates, with larger values during boreal summer, and the structure appears slightly distorted in winter. In DW2, both bands become prominent, with larger values during boreal winter, and the structure appears to be distorted during boreal summers. Simultaneously, SPW1 at 2 hPa dominates the winter high latitudes with amplitudes ranging from 10 to 20 K and is stronger in the Northern Hemisphere. It is very clearly seen that at the stratospheric altitudes over the low-latitude region, DS0 and DW2 amplitudes are significant and there is no one-to-one correlation with SPW1 in the higher latitudes.