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We present the zonal mean temperature variations for thequasi-biennial oscillation (QBO) and the semiannual oscillation (SAO) basedon data from SABER on the TIMED spacecraft (years 2002 to 2004) and from MLSon the UARS mission (1992 to 1994). The SABER measurements provide the rareopportunity to analyze data from one instrument over a wide altitude range(15 to 95 km), while MLS data were taken in the 16 to 55 km altitude range adecade earlier. The results are presented for latitudes from 48° S to48° N. New results are obtained for the QBO, especially in the upperstratosphere and mesosphere, and at mid-latitudes. At Equatorial latitudes,the QBO amplitudes show local peaks, albeit small, that occur at differentaltitudes. From about 20 to 40 km, and within about 15° of the Equator,the amplitudes can approach 3.5° K for the stratospheric QBO (SQBO). Forthe mesospheric QBO (MQBO), we find peaks near 70 km, with temperatureamplitudes reaching 3.5° K, and near 85 km, the amplitudes approach2.5° K. Morphologically, the amplitude and phase variations derived fromthe SABER and MLS measurements are in qualitative agreement. As a functionof latitude, the QBO amplitudes tend to peak at the Equator but thenincrease again pole-ward of about 15° to 20°. The phase progressionwith altitude varies more gradually at the Equator than at mid-latitudes.Many of the SAO results presented are also new, in part because measurementswere not previously available or were more limited in nature. At loweraltitudes near 45 km, within about 15° of the Equator, the temperatureamplitudes for the stratospheric SAO (SSAO) reveal a local maximum of about5° K. At higher altitudes close to the Equator, our results show separatepeaks of about 7° K near 75 and 90 km for the mesospheric SAO (MSAO). Inthe SAO results, significant inter-annual differences are evident, with theamplitudes being largest in 2002 relative to 2003 and 2004. As in the casefor the QBO, the SAO temperature amplitudes go through minima away from theEquator, and then increase towards mid latitudes, especially at altitudesabove 55 km. We compare our findings with previously published empiricalresults, and with corresponding results from the numerical spectral model(NSM). Although not a focus of this study, we also show results for theinter-annual variations (which appear to be generated at least in part bythe QBO) of the migrating diurnal tide. In the upper mesosphere, theiramplitudes can approach 20° K, and they are derived jointly with thezonal-mean components

annales geophysicae

Stratospheric and mesospheric temperature variations for the quasi-biennial and semiannual (QBO and SAO) oscillations based on measurements from SABER (TIMED) and MLS (UARS)