Six-hour zonally symmetric tidal oscillations of the winter mesopause over the South Pole Station

Sivjee, G. G.; Walterscheid, R. L.

doi:10.1016/0032-0633(94)00085-9

Cited by 58 publications

(41 citation statements)

References 20 publications

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“…The most characteristic periods of the oscillations are found to be rather uniformly spread between about 7 h and 12 h. It is interesting to note that oscillations with periods close to those of di erent tidal modes are not dominant in our results. Also having in mind the fact that all of the observed oscillations have zonal wave number one, we may conclude that the pseudo-tide mechanism, proposed by Walterscheid et al (Walterscheid et al, 1986;Sivjee et al, 1994), even if possible, is not the main mechanism which gave rise to the observed oscillations.…”

Section: Hernandezmentioning

confidence: 73%

Intradiurnal wind variations observed in the lower thermosphere over the South Pole

et al. 2000

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Abstract. The ®rst meteor radar measurements of meridional winds in the lower thermosphere (about 95 5 km), along four azimuth directions: 0°, 90°E, 180°and 90°W; approximately 2°from the geographic South Pole were made during two observational campaigns: January 19, 1995±January 26, 1996, and November 21, 1996±January 27, 1997. Herein we report analyses of the measurement results, obtained during the ®rst campaign, which cover the whole one-year period, with particular emphasis on the transient nature and seasonal behavior of the main parameters of the intradiurnal wind oscillations. To analyze the data, two complementary methods are used: the well-known periodogram (FFT) technique and the S-transform technique. The most characteristic periods of the intradiurnal oscillations are found to be rather uniformly spread between about 7 h and 12 h. All of these oscillations are westward-propagating with zonal wave number s 1 and their usual duration is con®ned to several periods. During the austral winter season the oscillations with periods less than 12 h are the most intensive, while during summer season the 12-h oscillations dominate. Lamb waves and internal-gravity wave propagation, non-linear interaction of the short-period tides, excitation in situ of the short period waves may be considered as possible processes which are responsible for intradiurnal wind oscillations in the lower thermosphere over South Pole.

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Section: Hernandezmentioning

confidence: 73%

Intradiurnal wind variations observed in the lower thermosphere over the South Pole

et al. 2000

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“…The dynamics of the neutral upper mesosphere/lower thermosphere (MLT) region over the South Pole has previously been investigated using optical-based experimental methods (Collins et al, 1992;Hernandez et al, 1992aHernandez et al, , 1992bHernandez et al, , 1993Hernandez et al, , 1995Fraser et al, 1993;Sivjee and Walterscheid, 1994). These studies have revealed some basic characteristics of atmospheric motions close to the rotational poles; for example, the flow field possesses a zonal wavenumber one (s = 1) structure, while scalar variables (such as temperature and OH-emission rates) are characterized by s = 0 (i.e., zonal symmetry).…”

Section: Introductionmentioning

confidence: 99%

Dynamics of the lower thermosphere over South Pole from meteor radar wind measurements

et al. 2014

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Hourly wind measurements were obtained nearly continuously over these time periods, at an approximate altitude of 95 km and at about 2• latitude from South Pole along the longitude meridians 0• , 90• E, 90• W, and 180• . The scientific advances achieved to date through analyses of these data are presented, including updates to several of our previously published works. The findings addressed herein include the following: (1) Strong divergences of zonal-mean meridional winds occasionally occur over South Pole, implying extreme vertical winds; (2) The monthly mean zonally asymmetric (zonal wavenumber s = 1) wind component varies during the year in a manner consistent with migration of the center of the polar vortex with respect to the geographic (rotational) pole; (3) Strong (>15 m/s) westward-propagating migrating diurnal (s = 1) and non-migrating semidiurnal (s = 1) oscillations exist except during winter months; (4) Long-period (∼2-10 days) waves exist during winter months which are primarily eastward-propagating; (5) Intradiurnal (periods ∼6-11.5 hours) westward-propagating oscillations exist, which are thought to be gravitational normal modes, or "Lamb" waves.

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“…Most of them are restricted to the short-period (6 and 8 hours) tidal oscillations in the high-latitude mesopause region [Sivjee and Walterscheid, 1994;Oznovich et al, 1997;Walterscheid and Sivjee, 2001], or to the zonally symmetric 12-and 24-h tides observed at 95 km height in the wind measurements from the HRDI and WINDII on UARS [Forbes et al, 2003;Huang and Reber, 2004]. Sivjee and Walterscheid [2002], however, analysing the airglow brightness low-frequency variability measured at Eureka, Canada (80°N) and South Pole station found fairly broadband spectral features of the mesopause region centred approximately at 17, 23 and 45 days.…”

Section: Introductionmentioning

confidence: 99%

Zonally symmetric oscillations in the Northern Hemisphere stratosphere during the winter of 2003–2004

Pancheva

Mukhtarov

Andonov

2007

Geophysical Research Letters

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[1] The paper presents clear evidence of zonally symmetric planetary waves with very large amplitudes present in the UK Met Office zonal wind data of the Northern Hemisphere stratosphere in the winter of 2003 -2004. The spectral analysis reveals that three prevailing periods of $23, 17 and 11 days contribute to the observed zonally symmetric oscillations. These waves are extracted from the data and their amplitudes and phases are studied in detail depending on height and latitude. The wave amplitudes -particularly those of the 11-and the 17-day zonally symmetric wavesclearly indicate the presence of two latitudinal branches of amplifications centred at 50-60°N and 20-30°N. The phase analysis shows that these waves are vertically upward propagating waves and that the waves from the high-latitude and tropical branches are almost out of phase. A possible forcing mechanism is suggested. The zonally symmetric waves play an important role in coupling the dynamical regimes of the high-and low-latitude stratosphere particularly during the major stratwarm event in the

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Six-hour zonally symmetric tidal oscillations of the winter mesopause over the South Pole Station

Cited by 58 publications

References 20 publications

Intradiurnal wind variations observed in the lower thermosphere over the South Pole

Intradiurnal wind variations observed in the lower thermosphere over the South Pole

Dynamics of the lower thermosphere over South Pole from meteor radar wind measurements

Zonally symmetric oscillations in the Northern Hemisphere stratosphere during the winter of 2003–2004

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