## 3 Tidal Characteristics of DS0 and DW2
### Altitude-Latitude Variations  
Monthly means of amplitudes and phases of the DS0 tide as a function of altitude and latitude from COSMIC, CMAM30, and ERA temperature data are shown in Figure 5, in the three columns, respectively. The first and second rows correspond to amplitudes and phases, respectively, during August 2008, representing boreal summer, and the third and fourth rows correspond to those during February 2009, representing boreal winter. The DS0 tide shows an amplitude of 1 K at 35 km over 5\({}^{\circ}\) N and 15\({}^{\circ}\) S during the summer of 2008 from COSMIC observations. Beyond 40 km, the amplitudes are negligible. This feature is not reliable due to the lower quality of COSMIC data above 40-45 km. The corresponding phase plot from COSMIC data shows that the two maxima are out of phase and anti-symmetric with respect to the equator. The vertical wavelength is approximately 20 km. In CMAM30 temperature data, DS0 shows an amplitude of 1 K at 1 hPa over 5\({}^{\circ}\) N and an amplitude of 0.6 K over 15\({}^{\circ}\) S during the summer of 2008. Amplitudes extend up from 10 hPa and above over the sub-tropical latitudes. DS0 shows secondary peaks with an amplitude of 0.6 K over \(\pm\)35\({}^{\circ}\) latitudes in both hemispheres, from altitudes of 3 hPa and above. Phases of DS0 indicate that the two maxima over the tropical latitudes are out of phase and anti-symmetric with respect to the equator with a vertical wavelength of 20 km, and those of the secondary peaks are in phase. In ERA temperature data, The DS0 tide shows slightly larger amplitudes of 1.5 K at 1 hPa over 5\({}^{\circ}\) N and 15\({}^{\circ}\) S during the summer of 2008. DS0 also shows second peaks with an amplitude of 0.6 to 1 K over 35\({}^{\circ}\) N and 40\({}^{\circ}\) S during the summer of 2008. These amplitudes are significant above 5 hPa. The phase of DS0 indicates that the two maxima over the tropical latitudes are out of phase and anti-symmetric with respect to the equator within a range of \(\pm\)30\({}^{\circ}\) latitudes and in phase over \(\pm\)40\({}^{\circ}\) latitudes. Vertical wavelengths are also similar to that of CMAM30. During winter, the amplitude of DS0 over these sub-tropical latitudes becomes negligible, and large amplitudes are observed in COSMIC in the high latitudes of the Northern Hemisphere. The vertical wavelength of this component is much larger. In CMAM30, the DS0 tide shows a peak with an amplitude of 0.6 K over the equator from CMAM30 data, and similar amplitudes are observed in the high latitudes of the Northern Hemisphere. The phase of DS0 is symmetric in nature with respect to the equator within the range of \(\pm\)40\({}^{\circ}\), and the vertical wavelength over the equator is approximately \(\sim\)30 km. In ERA temperature data, winter DS0 variability is slightly different. It shows a broad peak with an amplitude of 0.6 K over \(\pm\)20\({}^{\circ}\) latitudes. The phase plot is similar to CMAM30 and symmetric with respect to the equator. The vertical wavelength is approximately 30 km in CMAM30 and ERA-Interim during winter. The vertical and global structures of the DW2 tide showing the altitude-latitude variability during the summer of 2008 and winter of 2008/09 are shown in Figure 6. DW2 amplitudes are relatively smaller with an amplitude of 0.6 to 0.8 K at 35 km over 25\({}^{\circ}\) S in the Southern Hemisphere during the summer of 2008. A much smaller and negligible peak is observed over 5\({}^{\circ}\) N in the Northern Hemisphere. These two maxima are also anti-symmetric with respect to the equator. In CMAM30 temperature data, the DW2 amplitude is relatively smaller with values reaching 0.6 K over the equator during summer of 2008. In ERA-interim temperature data, DW2 shows a peak with an amplitude of 0.8 K over 5\({}^{\circ}\) S at 1 hPa. The phases are anti-symmetric with respect to the equator in both datasets, and the vertical wavelengths are approximately 25 km.