Nonlinear wave-wave interactions related to gravity wave reflection in the auroral upper F-region observed with the EISCAT radar

Y., S.; Schlegel, K.

doi:10.1016/0021-9169(93)90016-r

Cited by 8 publications

(6 citation statements)

References 37 publications

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“…Harmonic structure of gravity wave spectra has been reported previously using incoherent scatter radar data of vertical electron density profiles [ Yeh et al, 1979;Ma and Schlegel, 1993;Lanchester et al, 1993]. This is the first report of harmonic structure in the spectra of HF radar data.…”

Section: Discussionsupporting

confidence: 57%

Multiradar observations of medium‐scale acoustic gravity waves using the Super Dual Auroral Radar Network

Bristow¹,

Greenwald²

1996

J. Geophys. Res.

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Observations of medium‐scale acoustic gravity waves in the thermosphere, using multiple HF radars, are presented. Examples of waves from a magnetically quiet interval and a more magnetically active interval are examined along with statistics of gravity wave occurrence. It is shown that during quiet intervals gravity wave phase fronts may extend longitudinally for more than 3400 km. During the more active interval, the level of wave activity is elevated to the point that it is difficult to distinguish individual wave packets. Also, power spectra from the active period showed evidence of a harmonic sequence, indicating the possibility of some nonlinear process acting as the gravity waves propagate. Statistics of occurrence showed that high‐latitude medium‐scale gravity waves are more likely in the winter than in the summer and that the probability of observing waves on multiple radars is essentially the same as observing waves on any one radar.

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Section: Discussionsupporting

confidence: 57%

Multiradar observations of medium‐scale acoustic gravity waves using the Super Dual Auroral Radar Network

Bristow¹,

Greenwald²

1996

J. Geophys. Res.

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“…Day-to-day tidal variability is more dicult to be explained and is probably a result of several dierent mechanisms. Recent studies have revealed that strong wave-wave nonlinear interaction processes of gravity waves, tides and planetary waves in the MLT region play an important role in the dynamics of the middle atmosphere and certainly contribute signi®cantly to the short-term tidal variability (Fritts and Vincent, 1987;Manson and Meek, 1990;Huuskonen et al, 1991;Cevolani and Kingsley, 1992;RuÈ ster, 1992RuÈ ster, , 1994Ma and Schlegel, 1993;Pancheva and Mukhtarov, 1994;Mitchell et al, 1996;Kamalabadi et al, 1997). The theoretical studies of nonlinear wave-wave interaction (Teitelbaum et al, 1989;Teitelbaum and Vial, 1991) proposed that two primary waves can interact through the nonlinear advection terms of the momentum equation and produce, among others, two secondary waves whose frequencies, wave numbers and phases are the sum and dierence of the frequencies, wave number and phases of the primary waves.…”

Section: Introductionmentioning

confidence: 99%

Wavelet analysis on transient behaviour of tidal amplitude fluctuations observed by meteor radar in the lower thermosphere above Bulgaria

Pancheva

Mukhtarov

2000

Ann. Geophys.

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Abstract. On the basis of bispectral analysis applied to the hourly data set of neutral wind measured by meteor radar in the MLT region above Bulgaria it was demonstrated that nonlinear processes are frequently and regularly acting in the mesopause region. They contribute significantly to the short-term tidal variability and are apparently responsible for the observed complicated behavior of the tidal characteristics. A Morlet wavelet transform is proposed as a technique for studying nonstationary signals. By simulated data it was revealed that the Morlet wavelet transform is especially convenient for analyzing signals with: (1) a wide range of dominant frequencies which are localized in different time intervals; (2) amplitude and frequency modulated spectral components, and (3) singular, wave-like events, observed in the neutral wind of the MLT region and connected mainly with large-scale disturbances propagated from below. By applying a Morlet wavelet transform to the hourly values of the amplitudes of diurnal and semidiurnal tides the basic oscillations with periods of planetary waves (1.5-20 days), as well as their development in time, are obtained. A cross-wavelet analysis is used to clarify the relation between the tidal and mean neutral wind variability. The results of bispectral analysis indicate which planetary waves participated in the nonlinear coupling with the atmospheric tides, while the results of cross-wavelet analysis outline their time intervals if these interactions are local.Key words: Meteorology and atmospheric dynamics (middle atmosphere dynamics; waves and tides) - Radio science (nonlinear phenomena)

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“…Particularly the incoherent scatter technique provides a versatile tool for studying not only the wave frequencies and vertical wave numbers (e.g., Hearn and Yeh, 1977;Bertin et al, 1983;Schlegel, 1986;Sheen and Liu, 1988;Rice et al, 1988;Natorf et al, 1992;Ma and Schlegel, 1993;Lanchester et al, 1993;Wuttke, 1994), but also details of the fractional variations of various ionospheric plasma parameters such as the electron density, the electron temperature, the ion drift and the ion temperature which constitute the TID (Ma and Schlegel, 1992;Hocke, 1994;. The inter-relations between the measured TIDs and the AGWs causing them have been explored in detail with suitable models (e.g., the GIFTS Model, Kirchengast 1996a, b;Kirchengast et al, 1992Kirchengast et al, , 1995Kirchengast et al, , 1996.…”

Section: Introductionmentioning

confidence: 99%

Case studies of the propagation characteristics of auroral TIDS with EISCAT CP2 data using maximum entropy cross-spectral analysis

Schlegel

1998

Ann Geophysicae

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Abstract. In this paper case studies of propagation characteristics of two TIDs are presented which are induced by atmospheric gravity waves in the auroral F-region on a magnetic quiet day. By means of maximum entropy cross-spectral analysis of EISCAT CP2 data, apparent full wave-number vectors of the TIDs are obtained as a function of height. The analysis results show that the two events considered can be classi®ed as moderately large-scale TID and mediumscale TID, respectively. One exhibits a dominant period of about 72 min, a mean horizontal phase speed of about 180 m/s (corresponding to a horizontal wavelength of about 780 km) directed south-eastwards and a vertical phase speed of 55 m/s for a height of about 300 km. The other example shows a dominant period of 44 min, a mean horizontal phase velocity of about 160 m/s (corresponding to a horizontal wavelength of about 420 km directed southwestwards, and a vertical phase velocity of about 50 m/s at 250 km altitude.

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Nonlinear wave-wave interactions related to gravity wave reflection in the auroral upper F-region observed with the EISCAT radar

Cited by 8 publications

References 37 publications

Multiradar observations of medium‐scale acoustic gravity waves using the Super Dual Auroral Radar Network

Multiradar observations of medium‐scale acoustic gravity waves using the Super Dual Auroral Radar Network

Wavelet analysis on transient behaviour of tidal amplitude fluctuations observed by meteor radar in the lower thermosphere above Bulgaria

Case studies of the propagation characteristics of auroral TIDS with EISCAT CP2 data using maximum entropy cross-spectral analysis

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