The behavior of low-energy particles during substorms

Sharp, R. D.; Johnson, R. G.

doi:10.1016/0032-0633(72)90049-9

Cited by 15 publications

(3 citation statements)

References 19 publications

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“…There have been numerous previous experimental studies of substorm-injected particle fluxes, and in most cases a near-midnight injection region has been deduced [for example, Konradi, 1967;Freeman and Maguire, 1967;Parks and Winckler, 1968;DeForest and Mcllwain, 1971;Shelley et al, 1971;Parks et al, 1972;Sharp and Johnson, 1972;Konradi et al, 1973;Williams et al, 1974;Smith and Hoffman, 1974]. The azimuthal extent of the injection region is difficult to determine from satellite measurements, since orbital constraints result in either poor time resolution with good latitude coverage (low-altitude polar satellites) or poor latitude resolution and good time resolution (synchronous satellites); time resolution in this context refers to the ability to follow substorm development.…”

Section: Discussionmentioning

confidence: 99%

Plasma Injection at Synchronous Orbit and Spatial and Temporal Auroral Morphology

Eather¹,

Mende²,

Judge³

1976

J. Geophys. Res.

104

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Analysis of ATS 5 particle spectrograms and simultaneous meridian‐scanning photometer data (keograms) obtained at the base of the ATS field line has revealed systematic relationships between temporal and spatial auroral morphology and particle injection events. The details of these relationships depend on previous injection events, the local time of the observatory with respect to current injection events, and the extent and magnitude of current injections. A persistent zone of weak aurora is related to steady plasma sheet drizzle, and the equatorward edge of this aurora delineates field lines threading the inner edge of the plasma sheet. Auroras associated with injection events superimpose on this preexisting pattern, with the lowest latitude of new precipitation (the injection boundary) depending on local time. In general, plasma energization is not required between the equatorial plane and the ionosphere to account for observed auroral intensities, although there are examples when such energization probably occurs. The data also indicate occasional occurrence of enhanced loss cone fluxes, a fact suggesting low‐altitude field‐aligned acceleration. A summary figure shows how various characteristic auroral precipitation regions are related to the shape, extent, and orientation of the substorm injection boundary and to subsequent drift paths of injected plasma.

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Section: Discussionmentioning

confidence: 99%

Plasma Injection at Synchronous Orbit and Spatial and Temporal Auroral Morphology

Eather¹,

Mende²,

Judge³

1976

J. Geophys. Res.

104

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“…It has been suggested sometimes that the sudden loss of the intruding plasma caused by the explosive rise in the precipitation rate due to the cyclotron instability leads to the collapse of the field lines extended to the magnetotail. The plasma observations at the synchronous altitude, however, have revealed that the plasma flux is enhanced, instead of being depleted, at the onset of the expansion phase of the substorm[Sharp and Johnson, 1972]. Thus it is not certain that the precipitation loss plays an essential role in starting the expansion phase of the substorm.…”

mentioning

confidence: 99%

Synoptic survey for the neutral line in the magnetotail during the substorm expansion phase

Nishida¹,

Nagayama²

1973

J. Geophys. Res.

177

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The magnetic structure of the magnetotail during the expansion phase of the substorm is examined by summarizing observations made at more than fifty different locations scattered over the (solar magnetospheric) range of 0 ≳ x ≳ −65 RE, 20 ≳ y ≳ −20 RE, and 30 ≳ |z| ≥ 0 RE. It is found that all across the local‐time sector of |y| ≲ 15 RE, the neutral line is formed somewhere between x = −10 and −30 RE within ∼10 min of the onset of the substorm expansion phase. This is due to the severe weakening or disruption of the tail current inside x ≃ −20 RE. The neutral line continues to exist for about 1 hour, and its disappearance occurs almost as quickly as its formation. The role of the neutral line on the substorm process is discussed in the light of the above observation.

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“…Their work is based on the early work of Roux and Solomon [1971] (also see Sendrin [1972] Sharp and Johnson [1972]. Hcllwain [1972] analyzes the local-tine variations of particle distributions which can be produced by the sudden enhancement of a cross-tail electric field; paper (b l re-examines the deviation of a particle from its dipole magnetic drift shell in the presence of an electric field (see Stern [1971] for earlier work); and (c) analyzes the convection boundaries associated with the enhanced crossmagnetospheric electric fields occurring during the early stages of magnetic storms and substorms and was effectively used in the analysis of some Explorer-US data.…”

Section: The Inner Beltmentioning

confidence: 99%