Parametric decay of beam-driven Langmuir wave and enhanced ion-acoustic fluctuations in the ionosphere: a weak turbulence approach

Forme, F.

doi:10.1007/s005850050842

Cited by 30 publications

(48 citation statements)

References 10 publications

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“…The Parametric decay model describes the decay of beam driven Langmuir waves into ion-acoustic waves for the high-latitude homogeneous ionosphere [Forme, 1999]. It solves the Zakharov equations using the weak turbulence approximation, a statistical theory that de- …”

Section: Parametric Decay Of Beam-driven Langmuir Waves In a Large Scmentioning

confidence: 99%

Naturally enhanced ion acoustic fluctuations seen at different wavelengths

Forme¹,

Ogawa²,

Buchert³

2001

J. Geophys. Res.

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Abstract. We present European Incoherent Scatter (EISCAT) Svalbard Radar observations of enhanced incoherent scatter ion-acoustic spectra with transmitted frequencies slightly shifted relative to the radar central frequency. This study confirms the initial findings that (1) the nat•xrally enhanced ion acoustic lines sometimes show asymmetric power profiles and (2) the amplitude enhancement of upgoing and downgoing ion-acoustic waves occurs at somewhat different altitudes and different power levels. These observational facts are modeled using the parametric decay of beam driven Langmuir wave in an inhomogeneous medium. It is shown that the density gradient with altitude as well as the collisions contribute to an altitude variation of ion-acoustic spectra and may account for the observed signatures. It is also responsible for the transition from upshifted to downshifted enhanced ion lines. Our model shows that the power radiated by enhanced spectra varies with the wavelength and that the power difference between two wavelengths varies with altitude.

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Section: Parametric Decay Of Beam-driven Langmuir Waves In a Large Scmentioning

confidence: 99%

Naturally enhanced ion acoustic fluctuations seen at different wavelengths

Forme¹,

Ogawa²,

Buchert³

2001

J. Geophys. Res.

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“…This model was later refined (Forme, 1999) to explain the altitude dependence of spectral signatures, in particular cases where both shoulders are enhanced.…”

Section: Introductionmentioning

confidence: 99%

Ion-acoustic solitary waves and spectrally uniform scattering cross section enhancements

et al. 2010

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Abstract. Spectra measured by incoherent scatter radars are formed predominantly by scattering of the incident signal off ion-acoustic and Langmuir waves in the ionosphere. Occasionally, the upshifted and/or downshifted lines produced by the ion-acoustic waves are enhanced well above thermal levels and referred to as naturally enhanced ion-acoustic lines. In this paper, we study another kind of enhancement, which is spectrally uniform over the whole ion-line, i.e. the upand downshifted shoulder and the spectral valley in between. Based on observations made with the EISCAT Svalbard radar (ESR) facility, we investigate the transient and spectrally uniform power enhancements, which can be explained by ionacoustic solitary waves. We use a theory of nonlinear waves in a magnetized plasma to determine the properties of such waves and evaluate their effects on scattered signals measured by ESR. We suggest a new mechanism that can explain backscattered power enhancements by one order of magnitude above the thermal level and show that it is consistent with observations.

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“…Wahlund et al, 1992b) and iii) nonlinear wave-wave interaction, the parametric decay of Langmuir waves (e.g. Forme, 1993Forme, , 1999.…”

Section: Introductionmentioning

confidence: 99%

Particle precipitation during NEIAL events: simultaneous ground based nighttime observations at Svalbard

2009

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Abstract. In this paper we present Naturally Enhanced Ion Acoustic Lines (NEIALs) observed with the EISCAT Svalbard Radar (ESR) together with auroral emissions observed with the Meridian Scanning Photometer (MSP). This is the first report of NEIALs observed during nighttime at Svalbard. Previously, NEIALs have been associated with a strong red line intensity (>10 kR), which exceeds the green line intensities. The high intensity in the red line emission is a sign of abundant low energy electron precipitation. In our observations, one of the NEIAL events was accompanied by the red line emissions far below the previously reported intensities. This happened when the green line intensity exceeds the red line intensity. In this work we discuss the behaviour of electron precipitation characteristics and optical emissions during NEIAL events on the nightside, and we suggest that intensity enhancements in the 844.6 nm emission line could be a better candidate than the 630.0 nm emission as an optical signature for NEIALs.

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Parametric decay of beam-driven Langmuir wave and enhanced ion-acoustic fluctuations in the ionosphere: a weak turbulence approach

Cited by 30 publications

References 10 publications

Naturally enhanced ion acoustic fluctuations seen at different wavelengths

Naturally enhanced ion acoustic fluctuations seen at different wavelengths

Ion-acoustic solitary waves and spectrally uniform scattering cross section enhancements

Particle precipitation during NEIAL events: simultaneous ground based nighttime observations at Svalbard

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