A Safari‐Eiscat comparison between the velocity of F region small‐scale irregularities and the ion drift

Villain, J. P.; Caudal, G.; Hanuise, C.

doi:10.1029/ja090ia09p08433

Cited by 92 publications

(80 citation statements)

References 25 publications

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“…The use of HF frequencies meant that the SuperDARN radars measured the Doppler velocity of F-region irregularity backscatter targets moving with the ambient plasma at the E Â B convection velocity (Ossakow and Chataverdi 1979;Tsunoda 1988). The equivalence of these velocities was first shown for HF radar backscatter by Villain et al (1985) and later by Ruohoniemi et al (1987) using Goose Bay data. Further larger-scale statistical studies using other Super-DARN radars confirmed this relationship (Davies et al 1999Milan et al 1999a;Xu et al 2001;Drayton et al 2005).…”

Section: Measuring Global Convectionmentioning

confidence: 99%

A decade of the Super Dual Auroral Radar Network (SuperDARN): scientific achievements, new techniques and future directions

et al. 2007

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The Super Dual Auroral Radar Network (SuperDARN) has been operating as an international co-operative organization for over 10 years. The network has now grown so that the fields of view of its 18 radars cover the majority of the northern and southern hemisphere polar ionospheres. SuperDARN has been successful in addressing a wide range of scientific questions concerning processes in the magnetosphere, ionosphere,

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Section: Measuring Global Convectionmentioning

confidence: 99%

A decade of the Super Dual Auroral Radar Network (SuperDARN): scientific achievements, new techniques and future directions

et al. 2007

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“…In this case, the velocity measured by the radar should be a true indication of the line-of-sight component of the plasma drift velocity V EÂB (Villain et al, 1985;Ruohoniemi et al, 1987). It is interesting to note that at¯ow angles outside the cone of instability of the two-stream instability (i.e.…”

Section: Instability Mechanismsmentioning

confidence: 99%

“…Such structures provide steep electron density gradients in which smaller-scale irregularities can grow. Previous studies indicate that F-region irregularities observed by HF radars propagate with the plasma drift speed, V EÂB , and are not velocity limited (Villain et al, 1985;Ruohoniemi et al, 1987), making them suitable tracers of the plasmā ow.…”

Section: Introductionmentioning

confidence: 99%

Simultaneous observations at different altitudes of ionospheric backscatter in the eastward electrojet

Milan

Lester

1998

Ann. Geophys.

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Abstract. A common feature of evening near-range ionospheric backscatter in the CUTLASS Iceland radar ®eld of view is two parallel, approximately L-shellaligned regions of westward¯ow which are attributed to irregularities in the auroral eastward electrojet region of the ionosphere. These backscatter channels are separated by approximately 100±200 km in range. The orientation of the CUTLASS Iceland radar beams and the zonally aligned nature of the¯ow allows an approximate determination of¯ow angle to be made without the necessity of bistatic measurements. The twō ow channels have di erent azimuthal variations in¯ow velocity and spectral width. The nearer of the two regions has two distinct spectral signatures. The eastern beams detect spectra with velocities which saturate at or near the ion-acoustic speed, and have low spectral widths (less than 100 m s À1 ), while the western beams detect lower velocities and higher spectral widths (above 200 m s À1 ). The more distant of the two channels has only one spectral signature with velocities above the ionacoustic speed and high spectral widths. The spectral characteristics of the backscatter are consistent with Eregion scatter in the nearer channel and upper-E-region or F-region scatter in the further channel. Temporal variations in the characteristics of both channels support current theories of E-region turbulent heating and previous observations of velocity-dependent backscatter cross-section. In future, observations of this nature will provide a powerful tool for the investigation of simultaneous E-and F-region irregularity generation under similar (nearly co-located or magnetically conjugate) electric ®eld conditions.

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“…In the high-latitude ionosphere, these ionospheric irregularities are often present (Tsunoda, 1988). The irregularities move with the background plasma drift at F-region altitudes (Villain et al, 1985;Ruohoniemi et al, 1987) and so provide information about large-scale convection-related processes in the radar ®eld-of-view. The SuperDARN radars are therefore a very good diagnostic tool for studies of magnetosphereionosphere coupling.…”

Section: Instrumentationmentioning

confidence: 99%

High-time resolution conjugate SuperDARN radar observations of the dayside convection response to changes in IMF B<sub>y</sub>

et al. 2000

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Abstract. We present data from conjugate SuperDARN radars describing the high-latitude ionosphere's response to changes in the direction of IMF B y during a period of steady IMF B z southward and B x positive. During this interval, the radars were operating in a special mode which gave high-time resolution data (30 s sampling period) on three adjacent beams with a full scan every 3 min. The location of the radars around magnetic local noon at the time of the event allowed detailed observations of the variations in the ionospheric convection patterns close to the cusp region as IMF B y varied. A signi®cant time delay was observed in the ionospheric response to the IMF B y changes between the two hemispheres. This is explained as being partially a consequence of the location of the dominant merging region on the magnetopause, which is $8±12R E closer to the northern ionosphere than to the southern ionosphere (along the magnetic ®eld line) due to the dipole tilt of the magnetosphere and the orientation of the IMF. This interpretation supports the anti-parallel merging hypothesis and highlights the importance of the IMF B x component in solar wind-magnetosphere coupling.

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A Safari‐Eiscat comparison between the velocity of F region small‐scale irregularities and the ion drift

Abstract: Simultaneous data were obtained bet-Various kinds of ground-based facilities also proween the SAFARI HF coherent radars and the EISCAT vide an access to the ionospheric electric field. incoherent scatter experiment in December 1953. Incoherent scatter radars measure most parameters

Cited by 92 publications

References 25 publications

A decade of the Super Dual Auroral Radar Network (SuperDARN): scientific achievements, new techniques and future directions

A decade of the Super Dual Auroral Radar Network (SuperDARN): scientific achievements, new techniques and future directions

Simultaneous observations at different altitudes of ionospheric backscatter in the eastward electrojet

High-time resolution conjugate SuperDARN radar observations of the dayside convection response to changes in IMF B<sub>y</sub>

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A Safari‐Eiscat comparison between the velocity of F region small‐scale irregularities and the ion drift

Abstract: Simultaneous data were obtained bet-Various kinds of ground-based facilities also proween the SAFARI HF coherent radars and the EISCAT vide an access to the ionospheric electric field. incoherent scatter experiment in December 1953. Incoherent scatter radars measure most parameters

Cited by 92 publications

References 25 publications

A decade of the Super Dual Auroral Radar Network (SuperDARN): scientific achievements, new techniques and future directions

A decade of the Super Dual Auroral Radar Network (SuperDARN): scientific achievements, new techniques and future directions

Simultaneous observations at different altitudes of ionospheric backscatter in the eastward electrojet

High-time resolution conjugate SuperDARN radar observations of the dayside convection response to changes in IMF B&lt;sub&gt;y&lt;/sub&gt;

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High-time resolution conjugate SuperDARN radar observations of the dayside convection response to changes in IMF B<sub>y</sub>