On the power‐velocity relationship for 12‐ and 50‐MHz auroral coherent echoes

Makarevitch, R. A.; Ogawa, T.; Igarashi, K.; Koustov, A. V.; Sato, Natsuo; Ohtaka, Kazuhiro; Yamagishi, Hisakazu; Yukimatu, A. S.

doi:10.1029/2000ja000330

Cited by 12 publications

(25 citation statements)

References 28 publications

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“…This result agrees with our finding. Koustov et al (2001) and Makarevitch et al (2001) also reported smaller HF velocities as compared to 50-MHz velocities for large flow angles. They typically had the situation with HF/VHF data overlapped at far HF ranges (in the present study for such a situation we also had smaller HF velocities).…”

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

confidence: 98%

“…The neutral wind might affect both the HF and VHF velocity. Since at the range of HF echo power maxima the aspect angles of VHF echoes are worse, the neutral wind is expected to affect VHF velocities the strongest, since the neutral wind effect in velocity is significant for irregularities propagating/observed at large aspect angles (Makarevitch et al, 2001). For the period 14:00-15:00 UT in our event the predominantly westward neutral wind of ∼ 80 m/s was observed at the electrojet heights of ∼ 106 km (C. Meek, personal communication, MF radar observations at Tromsø).…”

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

confidence: 99%

“…Recently, attempts have been made to combine HF (12 MHz) and VHF (50 MHz) observations for studies of E-region high-latitude irregularities Makarevitch et al, 2001). These measurements showed differences in properties of meter and decameter irregularities.…”

Section: Introductionmentioning

confidence: 99%

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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: 98%

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

confidence: 99%

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Velocities of auroral coherent echoes at 12 and 144 MHz

et al. 2002

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“…In addition, there has been comparison of echo characteristics at widely differing frequencies, for instance in the HF and VHF bands (e.g. Koustov et al 2001Koustov et al , 2002Makarevitch et al 2001). However, in general, such approaches suffer from poor radar geometries and/or conflicting spatial and temporal resolutions.…”

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

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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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“…Over the last decade, the HF coherent radar studies of the plasma waves in the auroral E region have been extremely successful in identifying fundamental differences between irregularity properties at decameter scales as compared to meter-scale irregularities observed with VHF radars (Milan and Lester, 1998, 1999Jayachandran et al, 2000;Uspensky et al, 2001;Koustov et al, 2001Koustov et al, , 2002Koustov et al, , 2005Makarevitch et al, 2001Makarevitch et al, , 2002bMakarevitch et al, ,a, 2004Milan et al, 2003Milan et al, , 2004Makarevich, 2008;Carter and Makarevich, 2009). In particular, the HF echoes have been found to exhibit a wider Correspondence to: R. A.…”

Section: Introductionmentioning

confidence: 99%

HF echo types revisited: aspect angle attenuation effects

Makarevich

Carter

2009

Ann. Geophys.

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Abstract. The high-spatial-resolution observations of the auroral E-region echoes by the Super Dual Auroral Radar Network (SuperDARN) HF radar at Pykkvibaer, Iceland considered in a previous study are re-examined. Both the spectral power and Doppler velocity of the E-region HF echoes exhibit strong dependence on the slant range and expected off-perpendicular magnetic aspect angle (aspect angle attenuation). We consider the aspect angle attenuation effects in identification of spectral HF echo types. It is argued that echoes with Doppler velocities close to the nominal value of the ion-acoustic speed C s (∼350 m/s) and echoes with velocities greatly exceeding the C s (up to 600 m/s) are more related in their generation mechanisms than previously thought. It is proposed to treat the echoes near the C s as aspect-angle-attenuated counterparts of the high-velocity echoes and that both types are generated directly by the modified two-stream instability with aspect angle attenuation resulting in the preferential phase velocity saturation at the C s .

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On the power‐velocity relationship for 12‐ and 50‐MHz auroral coherent echoes

Cited by 12 publications

References 28 publications

Velocities of auroral coherent echoes at 12 and 144 MHz

Velocities of auroral coherent echoes at 12 and 144 MHz

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

HF echo types revisited: aspect angle attenuation effects

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