Normalized wavenumber spectra of the diurnal tides (from De5 to Dw5) at 45, 65, 95 and 105 km during NH spring (A) and summer (B) from eCMAM30 (upper panel) and SABER observation (lower panel). Positive (negative) wavenumber denotes westward (eastward) propagating tidal component. The latitude range for SABER is 50°N-50°S. White dashed lines denote 50°N/S. The contour scale is from zero to unity with the interval of 0.1.