Mesospheric standing waves near South Pole

Hernández, G.; Smith, Roger W.; Kelley, J. M.; Fraser, G. J.; Clark, K. C.

doi:10.1029/97gl01999

Cited by 15 publications

(32 citation statements)

References 14 publications

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“…The amplitude variation is systematic and can be described by a sinusoidal variation. A similar Hernandez et al (1997) which they attributed to a mesospheric standing oscillation. It appears that event 7 is consistent with the structure that Hernandez et al (1997) observed and may be considered a mesospheric standing oscillation.…”

Section: Identi®cation Of Wave Eventsmentioning

confidence: 71%

“…A similar Hernandez et al (1997) which they attributed to a mesospheric standing oscillation. It appears that event 7 is consistent with the structure that Hernandez et al (1997) observed and may be considered a mesospheric standing oscillation. Event 7 has a period close to 5.2 days (124 h), an amplitude of 8.9 AE 0.2 m s À1 and is propagating along the 121 E± 301 E AE 1.2 meridian.…”

Section: Identi®cation Of Wave Eventsmentioning

confidence: 71%

“…Event 7 has a period close to 5.2 days (124 h), an amplitude of 8.9 AE 0.2 m s À1 and is propagating along the 121 E± 301 E AE 1.2 meridian. During August 12±23, 1996 Hernandez et al (1997) identi®ed a mesospheric standing oscillation with an amplitude of 13 m s À1 , a period of 107 h propagating along the 119 E±299 E meridian. These two events would appear to be one and the same with the exception of a shift in time between them.…”

Section: Identi®cation Of Wave Eventsmentioning

confidence: 99%

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Transient eastward-propagating long-period waves observed over the South Pole

et al. 1998

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Abstract. Observations of the horizontal wind ®eld over the South Pole were made during 1995 using a meteor radar. These data have revealed the presence of a rich spectrum of waves over the South Pole with a distinct annual occurrence. Included in this spectrum are longperiod waves, whose periods are greater than one solar day, which are propagating eastward. These waves exhibit a distinct seasonal occurrence where the envelope of wave periods decreases from a period of 10 days near the fall equinox to a minimum of 2 days near the winter solstice and then progresses towards a period near 10 days at the spring equinox. Computation of the meridional gradient of quasi-geostrophic potential vorticity has revealed a region in the high-latitude upper mesosphere which could support an instability and serve as a source for these waves. Estimation of the wave periods which would be generated from an instability in this region closely resembles the observed seasonal variation in wave periods over the South Pole. These results are consistent with the hypothesis that the observed eastward propagating long-period waves over the South Pole are generated by an instability in the polar upper mesosphere. However, given our limited data set we cannot rule out a stratospheric source. Embedded in this spectrum of eastward propagating waves during the austral winter are a number of distinct wave events. Eight such wave events have been identi®ed and localized using a constant-®lter bank. The periods of these wave events ranges from 1.7 to 9.8 days and all exist for at least 3 wave periods. Least squares analysis has revealed that a number of these events are inconsistent with a wave propagating zonally around the geographic pole and could be related to waves propagating around a dynamical pole which is o set from the geographic pole. Additionally, one event which was observed appears to be a standing oscillation.

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Section: Identi®cation Of Wave Eventsmentioning

confidence: 71%

Section: Identi®cation Of Wave Eventsmentioning

confidence: 71%

Section: Identi®cation Of Wave Eventsmentioning

confidence: 99%

See 1 more Smart Citation

Transient eastward-propagating long-period waves observed over the South Pole

et al. 1998

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“…It can be easily seen that the selected oscillations reveal a very de®nite transient nature and are mainly separated by their time of appearance. Such transient behavior for the wind oscillations over the South Pole with periods of 11.6 h and 10 h has been noticed earlier (Hernandez et al, 1995;Hernandez et al, 1997). Usually each oscillation is signi®cant only for several periods of its existence.…”

Section: Frommentioning

confidence: 90%

“…They include di erences in the sampling statistics for di erent directions; frequency spectrum and background noise levels for di erent directions. In addition there are some background oscillations, perhaps as observed by Hernandez et al (1997) and Palo et al (1998), which may modulate the waves considered mainly in one direction and distort the spectrum.…”

Section: Frommentioning

confidence: 99%

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.

show abstract

Transient eastward-propagating long-period waves observed over the South Pole

et al. 1998

View full text Add to dashboard Cite

Observations of the horizontal wind ®eld over the South Pole were made during 1995 using a meteor radar. These data have revealed the presence of a rich spectrum of waves over the South Pole with a distinct annual occurrence. Included in this spectrum are longperiod waves, whose periods are greater than one solar day, which are propagating eastward. These waves exhibit a distinct seasonal occurrence where the envelope of wave periods decreases from a period of 10 days near the fall equinox to a minimum of 2 days near the winter solstice and then progresses towards a period near 10 days at the spring equinox. Computation of the meridional gradient of quasi-geostrophic potential vorticity has revealed a region in the high-latitude upper mesosphere which could support an instability and serve as a source for these waves. Estimation of the wave periods which would be generated from an instability in this region closely resembles the observed seasonal variation in wave periods over the South Pole. These results are consistent with the hypothesis that the observed eastward propagating long-period waves over the South Pole are generated by an instability in the polar upper mesosphere. However, given our limited data set we cannot rule out a stratospheric source. Embedded in this spectrum of eastward propagating waves during the austral winter are a number of distinct wave events. Eight such wave events have been identi®ed and localized using a constant-®lter bank. The periods of these wave events ranges from 1.7 to 9.8 days and all exist for at least 3 wave periods. Least squares analysis has revealed that a number of these events are inconsistent with a wave propagating zonally around the geographic pole and could be related to waves propagating around a dynamical pole which is oset from the geographic pole. Additionally, one event which was observed appears to be a standing oscillation.

show abstract

Mesospheric standing waves near South Pole

Cited by 15 publications

References 14 publications

Transient eastward-propagating long-period waves observed over the South Pole

Transient eastward-propagating long-period waves observed over the South Pole

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

Transient eastward-propagating long-period waves observed over the South Pole

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