Simultaneous HF measurements of E- and F-region Doppler velocities at large flow angles

Makarevitch, R. A.; Honary, F.; Koustov, A. V.

doi:10.5194/angeo-22-1177-2004

Cited by 25 publications

(46 citation statements)

References 23 publications

(35 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…6d), therefore, HF Doppler velocity limited in magnitude is unlikely to be caused by the small electric field intensity. The Doppler velocity at HF was featured recently in another study (Makarevitch et al, 2004), where the same conclusion was reached on the basis of the simultaneous Fand E-region CUTLASS observations during the event when the DMSP drift-meter measurements did not show any significant latitudinal variation of the convection component. Therefore, we will not discuss this issue any further, but note that the simultaneous HF/VHF observations provide yet another argument in support of this conclusion.…”

Section: Irregularity Doppler Velocity and Electrojet Directionsupporting

confidence: 53%

Meridional motions of the afternoon radar aurora, auroral electrojets, and absorption patches under variable IMF conditions

et al. 2004

Self Cite

View full text Add to dashboard Cite

Abstract. The meridional motions of the CUTLASS HF and STARE VHF coherent echoes, IMAGE equivalent electrojet currents, and IRIS absorption patches during the postnoon/early-evening event of 14 February 2000 are presented. The motions were found to be synchronous, to a first approximation, for all instruments. The temporal correlation between motions in the radar and magnetometer data was exceptionally good, although spatially the areas with the Eregion backscatter and most intense equivalent currents were not coincident, with the HF (VHF) echoes being shifted 100-200 km (20-50 km) equatorward (poleward). The meridional motions of the radar echoes and electrojet currents appeared to be controlled by the IMF B z changes; the meridional propagation direction was equatorward (poleward) during the intervals when the IMF was southward (northward), with one exception when the poleward progression continued after the IMF southward turning. We relate the observed meridional motion patterns to the polar cap expansion/contraction during variable IMF conditions and discuss the relative importance of two types of processes: the dayside reconnection and IMF-triggered substorms. We also investigate the irregularity Doppler velocity for the STARE (144 MHz) and CUTLASS (12 MHz) observations at large flow angles in the context of the eastward and westward electrojet systems. We show that the 144-MHz Doppler velocity is determined by a combination of two factors: the sense of electrojet currents and the aspect angle conditions within the STARE field of view. Finally, the behavior of small dayside enhancements of the IRIS absorption (up to 0.5 dB at 38.2 MHz) accompanying the radar echoes and electrojet currents is examined. Since the velocity of the meridional displacements was close to that of the poleward/equatorward progressing intense currents, it is suggested that the absorption patches observed during the event were related to the heating of the E-region plasma by the unstable plasma waves in the regions of enhanced electric fields.Correspondence to: R. A. Makarevitch (r.makarevitch@lancaster.ac.uk)

show abstract

Section: Irregularity Doppler Velocity and Electrojet Directionsupporting

confidence: 53%

Meridional motions of the afternoon radar aurora, auroral electrojets, and absorption patches under variable IMF conditions

et al. 2004

Self Cite

View full text Add to dashboard Cite

show abstract

“…Several studies showed that the SuperDARN E region velocity is well below the E×B component along the radar beam (e.g., Makarevitch et al, 2004;Koustov et al, 2005). However, usually, the amount of E-region echoes is not large enough to strongly affect the CPCP estimates.…”

Section: Discussionmentioning

confidence: 99%

On the SuperDARN cross polar cap potential saturation effect

et al. 2009

Self Cite

View full text Add to dashboard Cite

Abstract. Variation of the cross polar cap potential (CPCP) with the interplanetary electric field (IEF), the merging electric field E KL , the Polar Cap North (PCN) magnetic index, and the solar wind-magnetosphere coupling function E C of Newell et al. (2007) is investigated by considering convection data collected by the Super Dual Auroral Radar Network (SuperDARN) in the Northern Hemisphere. Winter and summer observations are considered separately. All variations considered show close to linear trend at small values of the parameters and tendency for the saturation at large values. The threshold values starting from which the non-linearity was evident were estimated to be IEF*∼E * KL ∼3 mV/m, PCN*∼3-4, and E * C ∼1.5×10 4 . The data indicate that saturation starts at larger values of the above parameters and reaches larger (up to 10 kV) saturation levels during summer. Conclusions are supported by a limited data set of simultaneous SuperDARN observations in the Northern (summer) and Southern (winter) Hemispheres. It is argued that the SuperDARN CPCP saturation levels and the thresholds for the non-linearity to be seen are affected by the method of the CPCP estimates.

show abstract

“…• Population ii echoes have u los values which appear proportional to v los (that is, a flow angle behaviour that is roughly a cosine dependence) with a constant of proportionality close to *0.2 (Milan et al 2003a;Makarevitch et al 2004;Koustov et al 2005). …”

Section: E-region Ionospheric Irregularitiesmentioning

confidence: 99%

“…This usually has to be inferred, with wide margins of uncertainty. In an attempt to overcome this, effort has been made to compare echo characteristics with F-region backscatter (Milan and Lester 1998;Makarevitch et al 2004), incoherent scatter radar measurements (Makarevitch et al 2006), or low-altitude spacecraft measurements . In addition, there has been comparison of echo characteristics at widely differing frequencies, for instance in the HF and VHF bands (e.g.…”

Section: E-region Ionospheric Irregularitiesmentioning

confidence: 99%

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

et al. 2007

View full text Add to dashboard Cite

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,

show abstract

Simultaneous HF measurements of E- and F-region Doppler velocities at large flow angles

Cited by 25 publications

References 23 publications

Meridional motions of the afternoon radar aurora, auroral electrojets, and absorption patches under variable IMF conditions

Meridional motions of the afternoon radar aurora, auroral electrojets, and absorption patches under variable IMF conditions

On the SuperDARN cross polar cap potential saturation effect

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

Contact Info

Product

Resources

About