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  • Author or Editor: A. D. Belmont x
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G. D. Nastrom
and
A. D. Belmont

Abstract

The diurnal component in meridional wind is estimated for each season at twelve rocket stations. Amplitudes and phases are presented as a function of height-latitude or as vertical profiles. Many of the gross features of the tide persist throughout the year, but as they migrate in height and latitude the amplitude or phase at a given location may undergo large changes with season. Longitudinal variations in the diurnal tide are found in the mid-stratosphere, and it is suggested they are coupled with longitudinal variations in the tropospheric temperature structure.

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G. D. Nastrom
and
A. D. Belmont

Abstract

The 12-year mean temperature and the amplitude and phase of the quasi-biennial oscillation (QBO) and first three harmonies of the annual wave are presented on height-latitude sections, 20 to 65 km, 80°N to 30°S. New features include adjusting the long-term mean temperature for errors due to solar radiation effects and for biasing by the diurnal tide. Due to the longer period of record used here, the extratropical QBO differs from that reported previously in the literature. Amplitudes of the annual wave at 30°S are larger than those at 30°N at all levels; the amplitude ratio is greatest near 50 km. The largest amplitude (7°C) of the semiannual wave in the stratosphere or mesosphere is near 75°N at 32 km. The terannual wave's amplitude near 35 km at 55°N is as large as the amplitude of the semiannual wave there and is larger than the well-known tropical %semiannual wave. These thermal properties of the upper atmosphere require theoretical explanations, stratosphere modelers should be able to reproduce them, and continued observations are needed to describe their hemispheric differences at high latitudes and altitudes.

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A. D. Belmont
and
D. G. Dartt

Abstract

Height-time sections of mean monthly observed upper-air zonal winds at stations within 20 degrees of the equator show not only an almost biennial oscillation of the wind in the middle or upper stratosphere but that there is a relative wave, 180 degrees out of phase to the first, which occurs in the lower stratosphere. The two waves are merged near the equator; they are best distinguished from each other about 9N to 15N and, although still noticeable as separate occurrences of westerlies from 15N to 20N, the intensity of the westerlies is much reduced. Both waves occur at progressively higher levels from one biennium to the next. This observed double cycle is caused by the combination of the fundamental annual and biennial waves, and the upward progression appears due to the difference in phase lags with height of these two component waves.

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A. D. Belmont
,
D. G. Dartt
, and
M. S. Ulstad

Abstract

The 10.7-cm solar radio flux is considered to be highly correlated with solar extreme ultraviolet radiation, thermospheric temperatures, sunspots, and the 27-day and 11-year solar cycles. To investigate the possibility of ultraviolet radiation being a cause of the quasi-biennial oscillation in tropical stratospheric winds and temperatures, the daily values of 10.7-cm flux were subjected to a non-linear, curve-fitting analysis to determine the major component sinusoidal frequencies of the time series. No evidence was found for a period near 26 months; hence, to the extent that extended ultraviolet 10-cm flux relationship is valid, ultraviolet insolation does not appear to vary with a quasi-biennial oscillation.

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