An experimental study of the propagation and dispersion of internal atmospheric gravity waves.

Ballard, K. A.

doi:10.1349/ddlp.1548

Cited by 4 publications

(13 citation statements)

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“…The inversion process used in this paper requires k• to be computed at 5-km intervals. This is done by means of this dispersion relation and a height dependent atmospheric model which is described comprehensively by Ballard [1981] and briefly below.…”

Section: Discussionmentioning

confidence: 99%

“…Values of ion mass density are estimated from empirical measurements of relative ion composition made by Hoffman et al [1969] and from the experimental measurements of electron number density. These quantities are also employed in the computation of ion-neutral collisional frequency from an expression provided by Banks and Kockarts [1973] which has been generalized for a multicomponent gaseous atmosphere [see Ballard, 1981]. The results described in the test have been obtained assuming a stationary atmosphere.…”

Section: Discussionmentioning

confidence: 99%

“…Power spectra for a given 4-hour time series (pretreated to have a zero mean) are determined using an adaptation of the Blackman and Tukey [1958] method with the Hamming window being employed as a lag window. Cross-spectral techniques, which are also based on Blackman and Tukey [1958], are employed as elucidated in the general literature [e.g., Jenkins and Watts, 1968; Otnes and Enochson, 1972] and described comprehensively by Ballard [1981].…”

Section: Spectral Analysesmentioning

confidence: 99%

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The height dependence of TID and gravity wave parameters

Tedd¹,

Morgan²,

Ballard³

1984

J. Geophys. Res.

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The height dependence of amplitude and both horizontal and vertical phase trace speeds, for individual spectral components of F region TID's, are obtained for the first time by means of a three‐station network of rapid‐run ionosondes. The corresponding causative gravity wave parameters are derived using a previously developed inversion technique, which is extended by incorporating the effects of dissipation and ion diffusion. Reasonable agreement is achieved between the height variation of the real part of the vertical component of the gravity wave phase propagation vector, kzr, obtained from the inversion process, and solutions of a dissipative dispersion relation for kzr at different heights. Height dependent values of the imaginary part of the vertical component of the gravity wave phase propagation vector, kzi, which are required for the inversion, are computed from the dissipative dispersion relation. Values of kzi obtained from analytic formulae which assume an isothermal atmosphere and small dissipation yield erroneous results for the waves considered, suggesting that care should be exercised when interpreting previous theoretical results that have employed these assumptions.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Spectral Analysesmentioning

confidence: 99%

See 1 more Smart Citation

The height dependence of TID and gravity wave parameters

Tedd¹,

Morgan²,

Ballard³

1984

J. Geophys. Res.

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“…Thermospheric winds may reach velocities comparable to those of gravity waves and their accompanying TID's [Cho and Yeh, 1970]. Yeh and Liu [1974] and Ballard [1981] show that whereas a con- Whereas it is found that a source located near an upstream station can cause complete absorption of the ionosonde echoes at that station, it is commonly found that the sources between stations, whose separation is some 275 km, produce no significant absorption at either adjacent station. It is found that the TID's proceed northward from a source as well as southward with bearing almost exactly opposed.…”

Section: The Effect Of Windsmentioning

confidence: 99%

Locating TID sources with a north‐south chain of rapid‐run ionosondes in western Québec

Morgan¹

1983

Radio Science

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Three rapid‐run ionosondes placed mutually 150 km apart for determination of the vector motion of traveling ionospheric disturbances, near L = 3.3 in northern New Hampshire and Vermont, were augmented with three more ionosondes laid out northward near L = 4.0. 4.5, and 6.0 in western Québec along the predominant direction (north‐northwest) from which daytime TID's arrive at the New Hampshire‐Vermont network. Observations were made for the 3‐month period March, April, May 1982. In a preliminary analysis, records have been reduced by our “slit‐scanner” technique to produce continuous displays of virtual height at selected frequencies moderately below the F layer critical. These isofrequency waveforms show a high degree of correlation among the three network stations, with propagation time delays from which speed and direction of TID travel can be deduced. An example, from 1980 observations, is shown of remarkable correlation over many daytime hours of the waveforms obtained by the network stations with that obtained by a sounder placed 1500 km downstream in the predominant direction (south‐southeast) toward which the TID's go. On the other hand, sources have now been found to be located as little as 200 km upstream from the network. TID's and their causative gravity waves propagate northward from these sources as well as southward. The sources are evidently narrow in north‐south extent for they frequently exist between the stations, spaced some 275 km apart, without causing absorption of ionosonde signals at either adjacent station. However, when they are located at an ionosonde station, they cause complete loss of echoes, thereby confirming that they are zones of energetic particle precipitation. They are believed to be due to precipitation from the outer radiation belt.

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“…The first and last sets, respectively, were obtained from iso-frequency virtual height contours, and the second from iso-true height contours, produced by Calder6n [1971], at the height of maximum TID amplitude. Values at other heights, but not presented here, were also produced by Ballard [1981] from the true height contours. our data (an increase in V with an increase in T) is consistent with that obtained from theoretical treatments of freely propagating waves (quasi-periods greater than 20 min) that take into account dissipative mechanisms for daytime atmospheric conditions [Klosterrneyer, 1974;Shibata and Okuzawa, 1983].…”

Section: Horizontal Dispersionmentioning

confidence: 99%

The dispersion of traveling ionospheric disturbances

Morgan¹,

Tedd²

1983

J. Geophys. Res.

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The horizontal dispersion of relatively large daytime TID events seen by the Dartmouth rapid-run ionosonde network is found to conform, at least qualitatively, to that predicted by previous theoretical treatments of freely propagating gravity waves in the presence of dissipation. The availability of TID vertical trace speeds, in addition to horizontal speeds, has allowed a direct comparison with gravity wave dispersion relations and dissipative criteria. Good agreement is found with theory for waves measured at the height of maximum gravity wave amplitude, but rather less convincing results are found at greater heights. The latter may be explained in part by the fact that ion diffusion was neglected in the inversion technique employed to derive the vertical component of the phase propagation vector of the gravity wave from that of the TID. 10,253

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An experimental study of the propagation and dispersion of internal atmospheric gravity waves.

Cited by 4 publications

References 0 publications

The height dependence of TID and gravity wave parameters

The height dependence of TID and gravity wave parameters

Locating TID sources with a north‐south chain of rapid‐run ionosondes in western Québec

The dispersion of traveling ionospheric disturbances

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