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Full-Text Articles in Physical Sciences and Mathematics
Relation Between The Occurrence Rate Of Esf And The Verticalplasma Drift Velocity At Sunset Derived Form Global Observations, C. Stolle, H. Luhr, Bela G. Fejer
Relation Between The Occurrence Rate Of Esf And The Verticalplasma Drift Velocity At Sunset Derived Form Global Observations, C. Stolle, H. Luhr, Bela G. Fejer
Bela G. Fejer
In this study, we investigate two global climatological data sets; the occurrence rate of Equatorial Spread- F (ESF), associated with equatorial plasma irregularities, at 400 km altitude obtained from CHAMP observations, and the evening equatorial vertical plasma drift, vz, from ROCSAT-1 measurements. First, as retrieved for a solar flux level of F10.7=150, the longitudinal variation of the two independently derived quantities correlates between 84% and 93% in the seasons December solstice, equinox and June solstice. The highest correlation is found for the solstice seasons when vz is integrated over local time around the prereversal enhancement (PRE) and displaced 6 towards …
Observationsof Inner-Plasmasphere Irregularities With A Satellite Beacon Interferometer Array, A. R. Jacobsen, G. Hogeveen, R. C. Carlos, G. Wu, Bela G. Fejer, M. C. Kelley
Observationsof Inner-Plasmasphere Irregularities With A Satellite Beacon Interferometer Array, A. R. Jacobsen, G. Hogeveen, R. C. Carlos, G. Wu, Bela G. Fejer, M. C. Kelley
Bela G. Fejer
A radio-interferometer array illuminated by 136-MHz beacons of several geosynchronous satellites has been used to study small (≥ 1013 m−2) transient disturbances in the total electron content along the lines of sight to the satellites. High-frequency (ƒ> 3 mHz) electron content oscillations are persistently observed, particularly during night and particularly during geomagnetically disturbed periods. The oscillations move across the array plane at speeds in the range 200–2000 m/s, with propagation azimuths that are strongly peaked in lobes toward the western half-plane. Detailed analysis of this azimuth behavior, involving comparison between observations on various satellite positions, indicates compellingly that the phase …
Long Wavelength Irregularities In The Equatorial Electrojet, E. Kudeki, D. T. Farley, Bela G. Fejer
Long Wavelength Irregularities In The Equatorial Electrojet, E. Kudeki, D. T. Farley, Bela G. Fejer
Bela G. Fejer
We have used the radar interferometer technique at Jicamarca to study in detail irregularities with wavelengths of a few kilometers generated in the unstable equatorial electrojet plasma during strong type 1 conditions. In-situ rocket observations of the same instability process are discussed in a companion paper. These large scale primary waves travel essentially horizontally and have large amplitudes. The vertical electron drift velocities driven by the horizontal wave electric fields reach or exceed the ion-acoustic velocity even though the horizontal phase velocity of the wave is considerably smaller. A straightforward extension to the long wavelength regime of the usual linear …
Reply (To "Comment On 'The Absolute Scattering Cross Section At50 Mhz Of Equatorial Electrojet Irregularities' By Farley Et Al." By N. D'Angelo), D. T. Farley, Bela G. Fejer
Reply (To "Comment On 'The Absolute Scattering Cross Section At50 Mhz Of Equatorial Electrojet Irregularities' By Farley Et Al." By N. D'Angelo), D. T. Farley, Bela G. Fejer
Bela G. Fejer
No abstract provided.
The Absolute Scattering Cross Section At 50 Mhz Ofequatorial Electrojet Irregularities, D. T. Farley, H. M. Ierkic, Bela G. Fejer
The Absolute Scattering Cross Section At 50 Mhz Ofequatorial Electrojet Irregularities, D. T. Farley, H. M. Ierkic, Bela G. Fejer
Bela G. Fejer
We have made carefully calibrated radar scattering measurements by using the large 50-MHz Jicamarca antenna. Typical results from the altitudes of maximum echo power for the vertically directed beam are σradar ∼1–2 × 10−10 m−1 for strong daytime electrojet conditions with type 1 irregularities present, with values a factor of 10 or so smaller during moderate conditions when only type 2 are observed. These cross sections, which are very large in comparison with those for incoherent scatter (σradar ≃5 × 10−18 m−1 for an electron density of 1011 m−3), are not nearly large enough, however, to cause pseudo-absorption events on …
Interferometer Studies Of Equatorial Fregion Irregularities And Drifts, E. Kudeki, Bela G. Fejer, D. T. Farley, H. M. Ierkic
Interferometer Studies Of Equatorial Fregion Irregularities And Drifts, E. Kudeki, Bela G. Fejer, D. T. Farley, H. M. Ierkic
Bela G. Fejer
A radar interferometer technique developed at Jicamarca, Peru and first used to study electrojet irregularities has now been used successfully to study plasma turbulence in the equatorial F region. Our first results have shown that the most ‘turbulent’ echoes appear to come from a region that extends for tens of kilometers in altitude but for only a kilometer or less in the east-west direction. This slab may very well be the wall of a depleted region, a plasma ‘bubble’. Sometimes the irregularities can be tracked as they move eastward or westward. Velocity profiles for the evening period obtained in this …
Ionospheric Irregularities, Bela G. Fejer, M. C. Kelley
Ionospheric Irregularities, Bela G. Fejer, M. C. Kelley
Bela G. Fejer
Extensive experimental and theoretical research has been performed in the last decade to study ionospheric irregularities. These studies have shown that plasma instabilities play a major role in the generation of the irregularities. In this work we describe in detail the recent experimental studies of the E and F region irregularities and also the extensive work on plasma instability theories developed to explain them. We also describe both radio wave and spacecraft-borne experimental techniques to allow a common ground for the understanding of the data from ground-based and in situ experiments. To date, theoretical work has been mostly concentrated on …
The Effect Of The Gradient-Drift Term On Type I Electrojet Irregularities, D. T. Farley, Bela G. Fejer
The Effect Of The Gradient-Drift Term On Type I Electrojet Irregularities, D. T. Farley, Bela G. Fejer
Bela G. Fejer
We hypothesize that type 1 VHF radar echoes can only be observed when the electrojet plasma is linearly unstable at half the radar wavelength and that further, for reasons not yet understood, the phase velocity of the unstable waves always corresponds to the threshold conditions for instability, even when the destabilizing forces (electron drift and plasma density gradient) exceed the threshold. This phase velocity, which produces the Doppler shift of the radar echoes, is usually close to the ion acoustic velocity of the medium but can differ from it to some extent because of the effect of the density gradient. …