Aliasing can also take place between stationary planetary waves (SPW) and non-migrating tides; for example, the stationary planetary wave of wavenumber one (SPW1) can alias into DS0 and DW2 [14; 30]. Other satellites such as Formosa Satellite-3/Constellation Observing System for Meteorology, Ionosphere and Climate (FORMOSAT-3/COSMIC) with a different sampling pattern are capable of addressing this aliasing problem and extracting short-term tidal variability in the Earth's atmosphere [14]. A shorter window size (\(\pm\)10 days) in analysing data helps to reduce the aliasing problem, but it still exists. Using numerical simulations, [PERSON] et al. [14] showed that non-stationary SPW1 variability causes more aliasing while a constant SPW1 variability results in zero aliasing. The theory of tidal variability in the stratosphere is discussed in several papers [1; 2; 3], and non-migrating tidal characteristics were identified in the stratosphere from ground-based measurements [7; 8; 31], satellite observations of TIMED Doppler Interferometer (TIDI)and SABER [28], UARS [32], the microwave limb sounder (MLS) [33], models [18], and reanalysis data [34]. Additionally, non-linear wave-wave interactions can also generate non-migrating tides [30]. SPW1 can interact non-linearly with DW1 and produce two child waves: DS0 and DW2 [12; 19; 35]. Observations show that the amplitudes of the non-migrating tides are very small in the high-latitude stratosphere and are believed to be produced due to such non-linear interactions between SPW1 and DW1 [24]. However, the amplitudes reported in this study using SABER data are unusually high. During the arctic winter of 2003-2004, DS0 and DW2 amplitudes were observed to range between 1 K and 3 K at 50 km over mid-latitudes [36]. DS0 and DW2 components in the wind field are found to vary from 5 to 15 m/s at 95 km in the Middle Atmosphere Circulation Model from Kyushu University (MACMKU), UARS, and Global Scale Wave Model (GSWM) data [30]. Recent numerical experiments show that non-linear interactions may not be an important source of the non-migrating tides in the high latitude stratosphere, as thought earlier [14], and are observed in SABER data due to aliasing [13; 14; 20]. Many studies also support the important role played by non-linear interactions in the generation of the non-migrating tides in the equatorial mesosphere. Over mid-latitudes, SPW1 is found to propagate upward and equator-ward and to generate DW2 via non-linear interaction with DW1 in the equatorial mesosphere [37]. [PERSON] et al. [19] calculated the correlation between SPW1 and DW2 for the winter of 2009-2010 and found this to be 0.55. Their results also show significant correlations between SPW1 and DW2 amplitudes during 20 winters in 31 years from the period 1979-2010. There is still a significant gap in understanding short-term variability in the middle atmosphere, particularly that of the non-migrating tides in the stratosphere, which cannot be addressed separately by satellite datasets due to the asynoptic nature of the measurements and associated aliasing problems. Thereby, models and reanalysis datasets have to be included for a better opportunity to investigate the tidal features in the atmosphere. With this motivation, non-migrating tides, DS0 and DW2, are investigated using data from CMAM30 and ERA-interim data in the stratosphere and compared with those obtained from COSMIC observations. The objective is to investigate their short-term variability and the importance of non-linear interactions in (1) the high-latitude stratosphere and (2) equatorial MLT region. Section 2 briefly describes the three datasets and the methodology, Section 3 describes the tidal characteristics determined, and Section 4 discusses the short term variability of the non-migrating diurnal tides including wavelet analysis and summarizes the results.