Compressional Pc5 type pulsations in the morningside plasma sheet

Vaivads, A.; Baumjohann, W.; Haerendel, G.; Nakamura, R.; Kucharek, H.; Klecker, B.; Lessard, M.; Kistler, L. M.; Mukai, T.; Nishida, A.

doi:10.5194/angeo-19-311-2001

Cited by 23 publications

(60 citation statements)

References 31 publications

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“…At dusk they occur during geomagnetically disturbed intervals, are associated with plasma injections, and propagate westward (sunward) at the 10-20 km s −1 gradient-curvature drift velocities expected for 10-30 keV ions (Barfield and McPherron, 1972;Takahashi et al, 1985). At dawn they occur during quiet intervals and move eastward (sunward) with phase velocities close to the plasma convection velocity (Vaivads et al, 2001). Wave periods may (Baumjohann et al, 1987;Constantinescu et al, 2009) or may not (Woch et al, 1990) increase with increasing radial distance, corresponding to decreasing magnetic field strength.…”

Section: Introductionmentioning

confidence: 99%

“…Compressional pulsations with periods ranging from 100 to more than 600 s are common in the equatorial morning and afternoon magnetosphere at distances beyond L=8 (e.g., Baumjohann et al, 1987;Takahashi et al, 1990a;Anderson et al, 1990;Zhu and Kivelson, 1991;Vaivads et al, 2000Vaivads et al, , 2001 when the plasma β is large (Zhu and Kivelson, 1994;Rae et al, 2007). At dusk they occur during geomagnetically disturbed intervals, are associated with plasma injections, and propagate westward (sunward) at the 10-20 km s −1 gradient-curvature drift velocities expected for 10-30 keV ions (Barfield and McPherron, 1972;Takahashi et al, 1985).…”

Section: Introductionmentioning

confidence: 99%

“…Case and statistical studies reveal that the waves typically exhibit wavelengths from 2000 to 7000 km and therefore wave 3726 G. I. Korotova et al: THEMIS observations of compressional pulsations in the dawn-side magnetosphere numbers m from 15 to 120 (e.g., Takahashi et al, 1985Takahashi et al, , 1990aZhu and Kivelson, 1991;Lessard et al, 1999;Vaivads et al, 2001).…”

Section: Introductionmentioning

confidence: 99%

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THEMIS observations of compressional pulsations in the dawn-side magnetosphere: a case study

et al. 2009

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Abstract. We present THEMIS-A low-and high-energy plasma, magnetic field, and energetic particle observations of long period (11-36 min) irregular compressional pulsations in the dawnside magnetosphere from 08:00 to 12:24 UT on 7 November 2007. We demonstrate that the pulsations maintain thermal and magnetic pressure balance, then employ finite gyroradius techniques to determine wave properties from the gyrophase distributions of 5-10 keV ions. The waves generally move sunward at velocities ∼10 km s −1 with the background plasma convection flow. Wavelengths range from 6700 to 23 300 km, corresponding to azimuthal wavenumbers m from 18 to 76. Wave periods decrease with increasing radial distance. Having determined the parameters describing the waves, we consider three previously proposed explanations: generation by substorm injection, generation by bounce or drift-bounce instabilities, and generation by the drift-mirror instability. The interval was quiet geomagnetically, arguing against any relationship to substorm injections. We found that ions with low energies of 69-628 eV or high energies of 28-615 keV would have been required to account for drift-bounce resonance during this interval, but inspection reveals ion fluxes at these energies near background levels during the time period considered. On the other hand, the criteria for the drift mirror instability are marginally satisfied. As predicted for the drift mirror instability, particle distributions peak more sharply near 90 • pitch angles during magnetic field strength enhancements than during strength depressions. At this point we therefore interpret the compressional pulsations observed by THEMIS A in terms of the drift mirror instability.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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THEMIS observations of compressional pulsations in the dawn-side magnetosphere: a case study

et al. 2009

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“…Among these waves, compressional pulsations with periods from 3 to 15 min play a prominent role in both the dawn and dusk magnetospheres at distances beyond L = 8 [e.g., Baumjohann et al, 1987;Takahashi et al, 1990;Anderson et al, 1990;Zhu and Kivelson, 1991;Vaivads et al, 2000Vaivads et al, , 2001 where the plasma β is large [Zhu and Kivelson, 1994;Rae et al, 2007].…”

Section: Introductionmentioning

confidence: 99%

“…Case and statistical studies reveal that the waves typically exhibit azimuthal wavelengths from 2000 to 7000 km and therefore azimuthal wave numbers from 15 to 120 [e. g., Takahashi et al, 1985Takahashi et al, , 1990Zhu and Kivelson, 1991;Lessard et al, 1999;Vaivads et al, 2001].…”

Section: Introductionmentioning

confidence: 99%

THEMIS observations of compressional poloidal pulsations in the dawnside magnetosphere: A case study

et al. 2013

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[1] We present results from a case study of compressional poloidal pulsations with periods ranging from 5 to 12 min in the dawn magnetosphere from 1630 to 2000 UT on 27 February 2011. However, we employ THEMIS (Time History of Events and Macroscale Interactions during Substorms) magnetic field, plasma, and energetic particle observations to determine azimuthal wavelengths (7000-27,000 km) and velocities (9-28 km/s) consistent with previous work. We then apply a new method invoking the north to south motion of the THEMIS spacecraft and the fact that the equatorial node exhibited north-south oscillations to derive the meridional structure of the wave in great detail. We determined that the amplitude of the meridional motion of the equatorial node was~0.8 R E , and that the meridional wave length exceeded 3 R E .

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Conjugate observation of auroral finger‐like structures by ground‐based all‐sky cameras and THEMIS satellites

2017

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In this study, we analyze the first conjugate observation of auroral finger‐like structures using ground‐based all‐sky cameras and the Time History of Events and Macroscale Interactions during Substorms (THEMIS) satellites and investigated associated physical processes that are a cause of auroral fragmentation into patches. Two events are reported: one is a conjugate event, and the other is a nearly conjugate event. The conjugate event was observed at Narsarsuaq (magnetic latitude: 65.3°N), Greenland, at 0720–0820 UT (0506–0606 LT) on 17 February 2012. Analysis of the event revealed the following observational facts: (1) variation of parallel electron energy fluxes observed by THEMIS‐E shows a correspondence to the auroral intensity variation, (2) plasma pressure and magnetic pressure fluctuate in antiphase with time scales of 5–20 min, and (3) perpendicular ion velocity is very small (less than 50 km/s). In the latter event, observed at Gakona, Alaska, on 2 February 2008, the THEMIS‐D satellite passed across higher latitudes of finger‐like structures. The data from THEMIS‐D also showed the antiphase fluctuation between plasma pressure and magnetic pressure and the small perpendicular ion velocity. From these observations, we suggest that the finger‐like structures are caused by a pressure‐driven instability in the balance of plasma and magnetic pressures in the magnetosphere.

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Compressional Pc5 type pulsations in the morningside plasma sheet

Cited by 23 publications

References 31 publications

THEMIS observations of compressional pulsations in the dawn-side magnetosphere: a case study

THEMIS observations of compressional pulsations in the dawn-side magnetosphere: a case study

THEMIS observations of compressional poloidal pulsations in the dawnside magnetosphere: A case study

Conjugate observation of auroral finger‐like structures by ground‐based all‐sky cameras and THEMIS satellites

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