On the spatial relationship of 1‐meter equatorial spread‐F irregularities and depletions in total electron content

Tsunoda, Roland T.; Towle, D. M.

doi:10.1029/gl006i011p00873

Cited by 45 publications

(27 citation statements)

References 18 publications

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“…This suggests that the micro variations are the manifestation of large-scale magnetic field-aligned structures like plasma bubbles which provide a platform for the generation of meter scale size plume structures. Earlier coordinated measurements (Tsunoda and Towle, 1979) revealing collocated large-scale bubble with meter scale size irregularities, provide support for the present observation. Owing to narrow band and narrow beam photometry, the plasma bubble and enhancement structures register micro variation in this type of photometry.…”

Section: Discussionsupporting

confidence: 73%

Characterization of VHF radar observations associated with equatorial Spread F by narrow-band optical measurements

et al. 2004

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Abstract. The VHF radars have been extensively used to investigate the structures and dynamics of equatorial Spread F (ESF) irregularities. However, unambiguous identification of the nature of the structures in terms of plasma depletion or enhancement requires another technique, as the return echo measured by VHF radar is proportional to the square of the electron density fluctuations. In order to address this issue, co-ordinated radar backscatter and thermospheric airglow intensity measurements were carried out during March 2003 from the MST radar site at Gadanki. Temporal variations of 630.0-nm and 777.4-nm emission intensities reveal smallscale ("micro") and large-scale ("macro") variations during the period of observation. The micro variations are absent on non-ESF nights while the macro variations are present on both ESF and non-ESF nights. In addition to the well-known anti-correlation between the base height of the F-region and the nocturnal variation of thermospheric airglow intensities, the variation of the base height of the F-layer, on occasion, is found to manifest as a bottomside wave-like structure, as seen by VHF radar on an ESF night. The micro variations in the airglow intensities are associated with large-scale irregular plasma structures and found to be in correspondence with the "plume" structures obtained by VHF radar. In addition to the commonly observed depletions with upward movement, the observation unequivocally reveals the presence of plasma enhancements which move downwards. The observation of enhancement in 777.4-nm airglow intensity, which is characterized as plasma enhancement, provides an experimental verification of the earlier prediction based on numerical modeling studies.

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Section: Discussionsupporting

confidence: 73%

Characterization of VHF radar observations associated with equatorial Spread F by narrow-band optical measurements

et al. 2004

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“…As plasma bubbles buoyantly rise upward, they become highly elongated in the vertical direction (Tsunoda and Towle, 1979), sometimes attaining very high altitudes (>1500 km) at the magnetic equator (Mendillo and Tyler, 1983;Sahai et al, 1994) and the depleted regions extend poleward in the flux tubes (Sales et al, 1996), reaching dip latitudes of over ±15 • (Rohrbaugh et al, 1989).…”

Section: Introductionmentioning

confidence: 99%

Generation of large-scale equatorial F-region plasma depletions during lowrange spread-F season

Sahai

Fagundes²,

Abalde³

et al. 2004

Ann. Geophys.

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“…This concept is supported by the work of Ossakow, et al (1979) where it is inferred that a bubble rising through the Flayer will bifurcate on its topside and produce shorter and shorter wavelength irregularities, either by a cascade or two-step mechanism. Experimental evidence to verify this position has come from an Altair radar experiment (Tsunoda, 1980a) which showed that backscatter maxima tend to occur at altitudes corresponding either to the electron density minima or the upper wall of the plasma depletion. More recently, Tsunoda (1980b) concluded that during the decay phase of meter scale backscatter plumes, the radar returns were maximum on the upper walls of the plasma depletions.…”

Section: Conclusion and Comparisons With Plumex Imentioning

confidence: 99%

Plumex II: A second set of coincident radar and rocket observations of equatorial spread‐F

Szuszczewicz¹,

Tsunoda²,

Narcisi³

et al. 1981

Geophysical Research Letters

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PLUMEX II, the second rocket in a two‐rocket operation that successfully executed coincident rocket and radar measurements of backscatter plumes and plasma depletions, was launched into the mid‐phase of well‐developed equatorial spread‐F. In contrast with the first operation, the PLUMEX II results show large scale F‐region irregularities only on the bottomside gradient with smaller scale irregularities (i.e., small scale structure imbedded in larger scale features) less intense than corresponding observations in PLUMEX I. The latter result could support current interpretations of east‐west plume asymmetry which suggests that during initial upwelling the western wall of a plume (the PLUMEX I case) is more unstable than its eastern counterpart (the PLUMEX II case). In addition, ion mass spectrometer results are found to provide further support for an ion transport model which "captures" bottomside ions in an upwelling bubble and transports them to high altitudes.

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On the spatial relationship of 1‐meter equatorial spread‐F irregularities and depletions in total electron content

Cited by 45 publications

References 18 publications

Characterization of VHF radar observations associated with equatorial Spread F by narrow-band optical measurements

Characterization of VHF radar observations associated with equatorial Spread F by narrow-band optical measurements

Generation of large-scale equatorial F-region plasma depletions during lowrange spread-F season

Plumex II: A second set of coincident radar and rocket observations of equatorial spread‐F

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