Excitation of short‐scale density structures by drift waves during ionospheric heating

Antani, S. N.; Guzdar, P. N.

doi:10.1029/1999gl003603

Cited by 2 publications

(4 citation statements)

References 4 publications

(5 reference statements)

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“…Lower aspect-sensitivity could result from a considerable amount of additional small-scale structure along the magnetic field. Theoretical work (Antani and Guzdar, 1999;Borisov, 2004) suggests that drift waves would be excited by the high temperature and density gradients associated with the artificial irregularities. These drift waves have already been suggested as a source of very small-scale fieldtransverse structure observed in in-situ measurements (Kelley et al, 1995;Kelley, 2004), although this is probably too weak to make a significant contribution to HF radar backscatter.…”

Section: Tid Effect On Hf Radar Observations Of the Artificial Irregumentioning

confidence: 99%

“…The saturation of the instability probably depends on a number of factors such as anomalous absorption of the pump wave (Robinson, 1989), the nonlinear increase in field-parallel thermal conductivity with electron temperature (Gurevich et al, 1995) and possibly destruction due to drift waves excited by the steep temperature and density gradients associated with the irregularities (Antani and Guzdar, 1999;Borisov, 2004).…”

Section: Introductionmentioning

confidence: 99%

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Effects of high-latitude atmospheric gravity wave disturbances on artificial HF radar backscatter

et al. 2006

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Abstract.Observations of HF radar backscatter from artificial field-aligned irregularities in an ionosphere perturbed by travelling disturbances due to atmospheric gravity waves are presented. Some features of the spatio-temporal structure of the artificial radar backscatter can be explained in terms of the distortion of the ionosphere resulting from the travelling disturbances. The distorted ionosphere can allow the HF pump wave to access upper-hybrid resonance at larger distances from the transmitter than are normally observed and can also prevent the pump wave reaching this resonance at close distances. The variation in altitude of the irregularities sometimes results in a significant variation in the elevation angle of arrival of the backscattered signal at the radar implying that the radar "sees" a target moving in altitude. We suggest that this may be evidence of off-orthogonal scattering from the irregularities.

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Section: Tid Effect On Hf Radar Observations Of the Artificial Irregumentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effects of high-latitude atmospheric gravity wave disturbances on artificial HF radar backscatter

et al. 2006

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“… Franz et al [1999] were the first to speculate that small‐scale structures might be inside the needles and showed that the scattering strength predicted by the PSD was in good agreement with the radar data. This speculation inspired Antani and Guzdar [1999] to calculate the drift wave growth rate based on the rocket data. They used the density depletion and temperature enhancement, both of which act to promote instability, and found that the most unstable waves have a mode number of 3, corresponding roughly to 10 m scale, and a spectral distribution of the form k −2 .…”

Section: Discussionmentioning

confidence: 99%

“…inspired Antani and Guzdar [1999] to calculate the drift wave growth rate based on the rocket data. They used the density depletion and temperature enhancement, both of which act to promote instability, and found that the most unstable waves have a mode number of 3, corresponding roughly to 10 m scale, and a spectral distribution of the form k À2 .…”

Section: Discussionmentioning

confidence: 99%

Evidence for drift waves in ionospheric heating experiments

Kelley

2004

Geophysical Research Letters

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Universal Drift Wave instabilities commonly occur in laboratory plasmas and yet have not been detected in space experiments. Meter‐scale waves occurring in convective ionospheric storms, also known as equatorial spread F conditions, were long thought, erroneously, to be caused by drift waves, even though laboratory simulations of the Rayleigh‐Taylor instability seem to result in drift modes. Most space‐based instabilities occur at such large scales that the gradients required to support drift waves are simply too weak. The results of a laboratory‐like experiment, performed in space using high power radiowaves, are then revisited. Such experiments produce modest density depletions having very short scales across the magnetic field. Here, wavelets are used to parse the signal into a deterministic structure—the needle‐like irregularities—and a noise‐like signal corresponding to waves trapped in the depletions, which are very likely lower hybrid drift waves. Recent space experiments have revealed natural phenomena with similar characteristics.

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Excitation of short‐scale density structures by drift waves during ionospheric heating

Abstract: Abstract.In this paper we investigate the role of dissipative drift instability in exciting "needle-like" short scale density structures recently observed during

Cited by 2 publications

References 4 publications

Effects of high-latitude atmospheric gravity wave disturbances on artificial HF radar backscatter

Effects of high-latitude atmospheric gravity wave disturbances on artificial HF radar backscatter

Evidence for drift waves in ionospheric heating experiments

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