Seasonal variation in equatorial mesospheric temperatures observed by SME

Near the equator, seasonal variability is dominated by a strong semiannual oscillation (SAO) whose amplitude increases from about 3 K in the lower mesosphere to 7.3 K near 80 km. Above 80 km, the amplitude of the oscillation decreases to a minimum at 83 km, but increases again sharply above that level, reaching 16.6 K at 90 km, the highest level observed. The structure of the temperature SAO is consistent with previous observations of the SAOs in temperature and zonal wind, although the very large amplitude at 90 km may be due in part to contamination by the diurnal tide. Just below 80 km, temperatures are wam (cold) near the solstices (equinoxes), implying westerly (easterly) accelerations above; the behavior at 58.5 km lags that at 80 km by about 2 months. -from Authors