Plasma flow bursts in the nightside auroral zone ionosphere and their relation to geomagnetic activity

Morelli, J. P.; Bunting, R. J.; Cowley, S. W. H.; Farrugia, C. J.; Freeman, M. P.; Friis‐Christensen, E.; Jones, G. O. L.; Lester, M.; Lewis, R. V.; Lühr, H.; Orr, D.; Pinnock, M.; Reeves, G. D.; Williams, P. J. S.; Yeoman, T. K.

doi:10.1016/0273-1177(93)90325-6

Cited by 5 publications

(3 citation statements)

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“…Since the advent of in situ measurements of the magnetospheric plasma by spacecraft instrumentation, it has been established that an enhancement ("injection") of energetic particle flux (both electrons and protons) at geostationary orbit is also a characteristic feature of the substorm expansion phase [e.g., Lanzerotti We study here a subset of the available instrumentation, but over the whole time span. Ten days (240 hours) were selected on the basis that at some time during them flow bursts [Williams et al, , 1992Lewis et al, 1993;Morelli et al, 1993] had been observed in the European Incoherent Scatter (EISCAT) radar IRishbeth and Williams, 1985] CP 2 programme data. Such a data interval represents an interval of higher than average magnetic activity.…”

Section: Introduction Motivation and Instrumentationmentioning

confidence: 99%

A comparison of midlatitude Pi 2 pulsations and geostationary orbit particle injections as substorm indicators

Yeoman¹,

Freeman²,

Reeves³

et al. 1994

J. Geophys. Res.

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Both the injection of energetic particles at geostationary orbit and ground magnetic observations of Pi 2 wave activity are characteristic indicators of the onset of the substorm expansion phase. Occurrence statistics for the appearance of electron and proton particle injection at three geostationary spacecraft and for the detection of midlatitude magnetic Pi 2 pulsations in a 3‐hour local time sector have been compiled from 240 hours of data. Throughout this interval a signature was detected on one or more of the instruments on average every 65 min. It is demonstrated that the detection of geostationary orbit particle injections and the detection of ground‐based Pi 2 pulsations are correlated at a very high significance level, and that both appear to be effective substorm indicators. However, a small percentage of events (∼10% in each case) may be identified as a Pi 2 event but not as an injection event or viceversa, without any obvious explanation, such as the local time of the observing instrumentation. A number of possible explanations for the discrepancies between the two data sets are discussed.

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Section: Introduction Motivation and Instrumentationmentioning

confidence: 99%

A comparison of midlatitude Pi 2 pulsations and geostationary orbit particle injections as substorm indicators

Yeoman¹,

Freeman²,

Reeves³

et al. 1994

J. Geophys. Res.

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“…The vertical line is drawn at 1844 UT which is coincident with the arrival of the north-south structure in the equatorward part of the bulge.From the electron data at 1984-037 and 1984-129, we can see that the substorm produced an injection of parti-more difficult to interpret since it can result from real dispersionless particle injections or local magnetic field perturbations or a combination of the two. This type of long duration, highly structured injection is not typical but has been associated with large, highly localized ionospheric flows[Morelli et al, 1993] and may be a characteristic signature of a BBF actually reaching geosynchronous orbit instead of being diverted at higher values of L. The primary thing to note from figure 3b is the clear dis-in a different plasma environment because either; a) changes in the magnetic field changed the flux tube that the spacecraft was on, b) a different plasma population arrived at the spacecraft independent of field perturbations, or c) both of these things occurred.…”

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Are north‐south aligned auroral structures an ionospheric manifestation of bursty bulk flows?

Henderson

Reeves

Murphree

1998

Geophysical Research Letters

198

195

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Abstract. Bursty Bulk Flow (BBF) events axe an important means of plasma transport in the Eaxth's magnetotail during substorms. While several studies have been performed using in-situ plasma and field data to determine the chaxacteristics of BBFs, remarkably little attention has been paid to the question of whether or not these events also manifest themselves in the auroral ionosphere. In this paper, we present observations from the Viking UV imager, and the Los Alamos National Laboratory geosynchronous energetic particle detectors that strongly suggest that the north-south aligned structures formed impulsively and repetitively during the expansion phase of substorms may be an ionospheric manifestation of BBFs.

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“…This agrees with the concept of substorm onset occurring in the near-Earth central plasma sheet (CPS) location, such that the boundary plasma sheet (BPS) and plasma sheet boundary layer (PSBL) remain unaffected for at least for the first ten minutes of the expansion phase after onset (see Persson et al, 1994a, b;Gazey et al, 1995). Radar data also indicate that the conductivity they produce can be so large as to initially reduce the local ionospheric electric field to almost zero (Morelli et al,1993). A similar suppression ofthe electric field in the high conductivity region of the main substorm expansion has been demonstrated by Weimer et al (1994).…”

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Opportunities for Magnetospheric Research Using EISCAT/ESR and Cluster.

Lockwood

Opgenoorth

1995

J. geomagn. geoelec

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The four Cluster spacecraft offer a unique opportunity to study structure and dynamics in the magnetosphere and we discuss four general ways in which ground-based remote-sensing observations of the ionosphere can be used to support the in-situ measurements. The ionosphere over the Svalbard islands will be studied in particular detail, not only by the ESR and EISCAT incoherent scatter radars, but also by optical instruments, magnetometers, imaging riometers and the CUTLASS bistatic HF radar. We present an on-line procedure to plan coordinated measurements by the Cluster spacecraft with these combined ground-based systems. We illustrate the philosophy of the method, using two important examples of the many possible configurations between the Cluster satellites and the ground-based instruments.

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Plasma flow bursts in the nightside auroral zone ionosphere and their relation to geomagnetic activity

Cited by 5 publications

References 4 publications

A comparison of midlatitude Pi 2 pulsations and geostationary orbit particle injections as substorm indicators

A comparison of midlatitude Pi 2 pulsations and geostationary orbit particle injections as substorm indicators

Are north‐south aligned auroral structures an ionospheric manifestation of bursty bulk flows?

Opportunities for Magnetospheric Research Using EISCAT/ESR and Cluster.

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