Development of shoulders and plumes in the frame of the interchange instability mechanism for plasmapause formation

Pierrard, V.; Lemaire, J.

doi:10.1029/2003gl018919

Cited by 59 publications

(84 citation statements)

References 14 publications

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“…These are now termed plasmaspheric plumes (Elphic et al, 1996;Goldstein et al, 2003). The plasmaspheric plume was successfully reproduced in previous simulation studies (Grebowsky, 1970;Chen and Wolf, 1972;Pierrard and Lemaire, 2004).…”

Section: Introductionmentioning

confidence: 59%

Multi-spacecraft observations of small-scale fluctuations in density and fields in plasmaspheric plumes

et al. 2012

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Abstract. In this event study, small-scale fluctuations in plasmaspheric plumes with time scales of ∼10 s to minutes in the spacecraft frame are examined. In one event, plasmaspheric plumes are observed by Cluster, while IMAGE measured density enhancement at a similar location. Fluctuations in density exist in plumes as detected by Cluster and are accompanied by fluctuations in magnetic fields and electric fields. Magnetic fluctuations are transverse and along the direction of the plumes. The E/B ratio is smaller than the Alfvén velocity. Another similar event is briefly presented. We then consider physical properties of the fluctuations. Alfvén mode modulated by the feedback instability is one possibility, although non-local generation is likely. It is hard to show that the fluctuations represent a fast mode. Interchange motion is possible due to the consistency between measurements and expectations. The energy source could be a pressure or density gradient in plasmaspheric plumes. When more events are accumulated so that statistical analysis becomes feasible, this type of study will be useful to understand the time evolution of plumes.

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Section: Introductionmentioning

confidence: 59%

Multi-spacecraft observations of small-scale fluctuations in density and fields in plasmaspheric plumes

et al. 2012

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“…Recently, dynamical simulations based on this mechanism have been developed (Pierrard and Lemaire, 2004) and compared with recent observations of the plasmasphere by AURORAL PROBE, CLUSTER and IMAGE (Bezrukikh et al, 2003;Dandouras et al, 2005;Pierrard and Cabrera, 2005). In the present paper, some typical results of the dynamical simulations are presented and compared with the observations of EUV/IMAGE during quiet periods, when the plasmasphere is quite extended, and during geomagnetic substorms, when plumes are generated.…”

Section: Introductionmentioning

confidence: 94%

“…Moreover, due to the differential rotation, a plume is formed later in the afternoon or dusk region. The mechanism is described in details by Pierrard and Lemaire (2004).…”

Section: Plasmapause Formationmentioning

confidence: 99%

Dynamical Simulations of Plasmapause Deformations

Pierrard

Cabrera

2006

Space Sci Rev

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Abstract. Dynamical simulations have been developed at IASB-BIRA to model the deformations of the plasmasphere during geomagnetic substorms and other variations in the level of geomagnetic activity. The simulations are based on the mechanism of plasma instability and use the empirical Kp-dependent electric field E5D. The results of the simulations are compared with IMAGE observations that provide the first global comprehensive images of the Earth's plasmasphere. The predicted plasmapause positions correspond generally rather satisfactorily with the EUV observations. The plasmasphere is rather extended in all MLT sectors during quiet periods. During or just after geomagnetic substorms, the plasmaspause is sharper and becomes closer to the Earth in the night sector. Periods of enhanced geomagnetic activity are associated to the formation of plumes that rotate with the plasmasphere. The simulations reproduce the formation and the motion of these plumes, as well as the development of other structures like shoulders observed at the plasmapause by EUV on IMAGE.

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“…In order to fit this scenario with the observed ray path orientation in the X-Y plane (toward the night-dusk sector), we propose that a shoulder could have been formed at the start of the active period, together with particle injections triggering the NTC radiation. Shoulders are indeed known to form in the dawn sector (Pierrard and Lemaire, 2004). The ray path orientation in the Y -Z plane (toward south) would fit emission from medium latitudes of a plasmapause L shell surface elongated near the equator.…”

Section: Morphologymentioning

confidence: 99%

Remote sensing of a NTC radio source from a Cluster tilted spacecraft pair

Décréau¹,

Kougblénou²,

Lointier³

et al. 2013

Ann. Geophys.

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Abstract. The Cluster mission operated a "tilt campaign" during the month of May 2008. Two of the four identical Cluster spacecraft were placed at a close distance (∼ 50 km) from each other and the spin axis of one of the spacecraft pair was tilted by an angle of ∼ 46 • . This gave the opportunity, for the first time in space, to measure global characteristics of AC electric field, at the sensitivity available with long boom (88 m) antennas, simultaneously from the specific configuration of the tilted pair of satellites and from the available base of three satellites placed at a large characteristic separation (∼ 1 R E ). This paper describes how global characteristics of radio waves, in this case the configuration of the electric field polarization ellipse in 3-D-space, are identified from in situ measurements of spin modulation features by the tilted pair, validating a novel experimental concept. In the event selected for analysis, non-thermal continuum (NTC) waves in the 15-25 kHz frequency range are observed from the Cluster constellation placed above the polar cap. The observed intensity variations with spin angle are those of plane waves, with an electric field polarization close to circular, at an ellipticity ratio e = 0.87. We derive the source position in 3-D by two different methods. The first one uses ray path orientation (measured by the tilted pair) combined with spectral signature of magnetic field magnitude at source. The second one is obtained via triangulation from the three spacecraft baseline, using estimation of directivity angles under assumption of circular polarization. The two results are not compatible, placing sources widely apart. We present a general study of the level of systematic errors due to the assumption of circular polarization, linked to the second approach, and show how this approach can lead to poor triangulation and wrong source positioning. The estimation derived from the first method places the NTC source region in the dawn sector, at a large L value (L ∼ 10) and a medium geomagnetic latitude (35 • S). We discuss these untypical results within the frame of the geophysical conditions prevailing that day, i.e. a particularly quiet long time interval, followed by a short increase of magnetic activity.

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Development of shoulders and plumes in the frame of the interchange instability mechanism for plasmapause formation

Cited by 59 publications

References 14 publications

Multi-spacecraft observations of small-scale fluctuations in density and fields in plasmaspheric plumes

Multi-spacecraft observations of small-scale fluctuations in density and fields in plasmaspheric plumes

Dynamical Simulations of Plasmapause Deformations

Remote sensing of a NTC radio source from a Cluster tilted spacecraft pair

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