Observations of auroral E-region plasma waves and electron heating with EISCAT and a VHF radar interferometer

Providakes, J.; Farley, D. T.; Fejer, Bela G.; Sahr, John D.; Swartz, Wesley E.; Häggström, Ingemar; Hedberg, Å.; Nordling, J. A.

doi:10.1016/0021-9169(88)90019-0

Cited by 65 publications

(47 citation statements)

References 32 publications

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“…For observations along the electrojet (inside the FB instability cone), this question has been studied in a number of papers (e.g. Providakes et al, 1988;Haldoupis and Schlegel, 1990). There has not been so much focus on ob- servations outside the FB instability cone.…”

Section: Is Stare Velocity a Cosine Component Of Convection?mentioning

confidence: 99%

Velocities of auroral coherent echoes at 12 and 144 MHz

et al. 2002

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Abstract. Two Doppler coherent radar systems are currently working at Hankasalmi, Finland, the STARE and CUTLASS radars operating at ∼ 144 MHz and ∼ 12 MHz, respectively. The STARE beam 3 is nearly co-located with the CUTLASS beam 5, providing an opportunity for echo velocity comparison along the same direction but at significantly different radar frequencies. In this study we consider an event when STARE radar echoes are detected at the same ranges as CUT-LASS radar echoes. The observations are complemented by EISCAT measurements of the ionospheric electric field and electron density behaviour at one range of 900 km. Two separate situations are studied; for the first one, CUTLASS observed F-region echoes (including the range of the EIS-CAT measurements), while for the second one CUTLASS observed E-region echoes. In both cases STARE E-region measurements were available. We show that F-region CUT-LASS velocities agree well with the convection component along the CUTLASS radar beam, while STARE velocities are typically smaller by a factor of 2-3. For the second case, STARE velocities are found to be either smaller or larger than CUTLASS velocities, depending on the range. Plasma physics of E-and F-region irregularities is discussed in attempt to explain the inferred relationship between various velocities. Special attention is paid to ionospheric refraction that is important for the detection of 12-MHz echoes.

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Section: Is Stare Velocity a Cosine Component Of Convection?mentioning

confidence: 99%

Velocities of auroral coherent echoes at 12 and 144 MHz

et al. 2002

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“…Since usual auroral radars provide no height resolution of the backscattered power, unless interferometer techniques are used (Providakes et al, 1983(Providakes et al, , 1988, it is interesting to study the 300-m resolution data of the ALOMAR SOUSY radar in more detail. Figure 3 (upper panel) shows ®ve successive height pro®les of the backscattered power.…”

Section: Height Pro®lesmentioning

confidence: 99%

“…We apply a radar equation suitable for volume backscatter (Farley et al, 1981): The line styles corresponding to the dierent beam directions, indicated in the lower panel, apply to all three panels r t g 2 sk 2 q 32p 2 r 2 r (where r , t is received and transmitted echo power, g is antenna eciency, s is transmitter pulse width, k is radar wave length, G is receiver antenna gain, r is distance to the scattering volume, and r is volume backscatter cross section) to two dierent radars of comparable operating wavelength: our radar and the CUPRI radar of the Cornell group which was widely used for auroral studies (e.g. Providakes et al, 1988, additional information has been provided by J. Sahr, private communication).…”

Section: Backscattered Powermentioning

confidence: 99%

Non-magnetic aspect sensitive auroral echoes from the lower E region observed at 50 MHz

Rüster

Schlegel

1999

Ann. Geophys.

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Abstract.Backscatter from E-region irregularities was observed at aspect angles close to 90°(almost parallel to the direction of the magnetic ®eld) using the ALOMAR SOUSY radar at Andoya/Norway. Strong electric ®elds and increased E-region electron temperatures simultaneously measured with the incoherent scatter facility EISCAT proved that the Farley-Buneman plasma instability was excited. In addition, strong particle precipitation was present as inferred from EISCAT electron densities indicating that the gradient drift instability may have been active, too. Backscatter at such large aspect angles was not expected and has not been observed before. The characteristics of the observed echoes, however, are in many aspects completely dierent from usual auroral radar results: the Doppler velocities are only of the order of 10 m/s, the half-width of the spectra is around 5 m/s, the echoes originate at altitudes well below 100 km, and they seem to be not aspect-sensitive with respect to the magnetic ®eld direction. We, therefore, conclude that the corresponding irregularities are not caused by the mentioned instabilities and that other mechanism have to be invoked.

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“…[2] For some twenty years numerous radar observations demonstrate an intriguing effect of dramatically elevated electron temperature, up to three thousand Kelvin, in the auroral or subauroral (polarization) electrojets during magnetic storms [Schlegel and St.-Maurice, 1981;Providakes et al, 1988;Stauning and Olesen, 1989;Williams et al, 1992;Foster and Erickson, 2000]. Strong electron heating always correlates with a strong convection electric field E C .…”

Section: Introductionmentioning

confidence: 99%

“…, cannot heat electrons significantly more than the convection electric field E C itself and hence cannot account for the observed extreme values of the electron temperature T e . It is small components of the turbulent electric field parallel to the magnetic field, dE || , that play a crucial role in anomalous heating of electrons [St.-Maurice and Laher, 1985;Providakes et al, 1988;Milikh et al, 2001].…”

Section: Introductionmentioning

confidence: 99%

Kinetic model of electron heating by turbulent electric field in the E region

Milikh

Dimant

2002

Geophysical Research Letters

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[1] Numerous radar observations demonstrate anomalously strong electron heating in polar electrojets during magnetic storms. The effect correlates with strong convection electric field. Anomalous heating of electrons is caused by turbulent electric fields developing in the E region due to the Farley-Buneman instability. A quantitative model of the effect is proposed. Numerical computations are based on a kinetic code. A good agreement of the theoretical results with the existing observations supports the physical ideas underlying the model.

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Observations of auroral E-region plasma waves and electron heating with EISCAT and a VHF radar interferometer

Cited by 65 publications

References 32 publications

Velocities of auroral coherent echoes at 12 and 144 MHz

Velocities of auroral coherent echoes at 12 and 144 MHz

Non-magnetic aspect sensitive auroral echoes from the lower E region observed at 50 MHz

Kinetic model of electron heating by turbulent electric field in the E region

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