Temperature diurnal variations (migrating tides) in the stratosphere and lower mesosphere based on measurements from SABER on TIMED

Derived diurnal variations of temperature (diurnal migrating tides) in the stratosphere and lower mesosphere based on satellite measurements from SABER on TIMED are presented. They complement earlier studies by us and by others that concentrated on higher altitudes. The amplitudes range from less than 1°K to a few °K, compared to those in the upper mesosphere, which can reach 20°K. They are important to the understanding of the dynamics and energetics and can be of additional value when used with previous measurements that have records spanning decades but which do not provide adequate information to estimate diurnal variations. We compare with results by others based on satellite and ground‐based measurements. At low altitudes (∼25–12 hPa), the comparisons are generally quite good, even for magnitudes of 1° or less. With increasing altitude, the diurnal amplitudes display asymmetry with respect to the equator on latitude versus day coordinates up to about 1 hPa (∼48 km), where a transition begins, and the morphology becomes reminiscent of the first symmetric propagating mode of the migrating tide. A transition also appears in the diurnal phase gradient with respect to altitude, where the regular progression of the diurnal phase becomes significantly smaller at altitudes from about 2.8 to 0.22 hPa. The seasonal variations can show significant semiannual behavior that peak near equinox but are less obvious at lower altitudes below ∼10 hPa. Interannual variations in the upper stratosphere are qualitatively consistent with those found previously at higher altitudes by us.