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

Nishida, A.; Nagayama, N.

doi:10.1029/ja078i019p03782

Cited by 177 publications

(96 citation statements)

References 22 publications

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“…Nishida and Nagayama (1973) offer further statistical evidence that the tail-lobe B increase propagates down the tail, appearing at later times as the moon's orbit is approached.…”

Section: Tail-lobe Magnetic Variationsmentioning

confidence: 74%

“…The study of Nishida and Nagayama (1973) indicates that a macroscopic neutral line is formed within 10 minutes of the low-latitude positivebay onset in the neutral sheet at distances of 15 to 25 RE down the tail. producing an 0-type neutral line at greater distances down the tail (Akasofu and Chapman, 1961;, and this has not been observed by Nishida and Nagayama (1973) to occur at the time of low-latitude onset.…”

Section: Plasma and Magnetic Behavior Near The Neutral Sheetmentioning

confidence: 96%

“…Such adjustments of large-scale magnetospheric flow patterns often can be inferred from phenomena such as ground magnetic variations at polar-cap and equatorial latitudes (Nishida and Kokubun, 1971;, variations in tail-lobe magnetic energy density (Aubry and McPherron, 1971;Nishida and Nagayama, 1973;Meng and Colburn, 1973), and latitudinal shifts of dayside auroras and the associated F-layer irregularity.zones or FLIZ . Quantitative studies of such phenomena as they -14 -respond to changes in the strength and direction of .the INF are beginning to yield important new information on the nature of the interaction between the interplanetary and geomagnetic fields.…”

Section: The Interplanetary Magnetic Field and Magnetospheric Convectionmentioning

confidence: 99%

“…A very detailed study of magnetic and plasma variations occurring near the neutral sheet (where the gradual thinning is not clearly apparent) has, however, been conducted by Nishida and Nagayama (1973) and Nishida and Hones (1973). The use of the low-latitude positive-bay onset as an ordering parameter in these two studies has resulted in an important clarification of the relationship of the formation of macroscopic X-type neutral lines in the tail to substorm temporal development, a relationship suggested by Camidge and Rostoker (1970) and discussed further by Rostoker and Camidge (1971).…”

Section: Plasma and Magnetic Behavior Near The Neutral Sheetmentioning

confidence: 99%

“…The use of the low-latitude positive-bay onset as an ordering parameter in these two studies has resulted in an important clarification of the relationship of the formation of macroscopic X-type neutral lines in the tail to substorm temporal development, a relationship suggested by Camidge and Rostoker (1970) and discussed further by Rostoker and Camidge (1971). The study of Nishida and Nagayama (1973) indicates that a macroscopic neutral line is formed within 10 minutes of the low-latitude positivebay onset in the neutral sheet at distances of 15 to 25 RE down the tail. producing an 0-type neutral line at greater distances down the tail (Akasofu and Chapman, 1961;, and this has not been observed by Nishida and Nagayama (1973) to occur at the time of low-latitude onset.…”

Section: Plasma and Magnetic Behavior Near The Neutral Sheetmentioning

confidence: 99%

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Observations of interactions between interplanetary and geomagnetic fields

Burch¹

1974

Reviews of Geophysics

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Magnetospheric effects associated with variations of the north‐south component of the interplanetary magnetic field (IMF) are examined in light of recent experimental and theoretical results. Although the occurrence of magnetospheric substorms is statistically related to periods of southward IMF, the details of the interaction are not understood. In particular, attempts to separate effects resulting directly from the interaction between interplanetary and geomagnetic fields from those associated with substorms have produced conflicting results. One can, however, say with some assurance that the transfer of magnetic flux from the day side to the night side magnetosphere, as evidenced by equatorward motion of the polar cusp and increases of the magnetic energy density in the lobes of the geomagnetic tail, is a direct consequence of the southward IMF. On the other hand, the formation of a macroscopic X‐type neutral line at tail distances less than 35 RE appears to be a substorm phenomenon. Although other plasma and field phenomena in the outer magnetosphere and at low altitudes may be directly associated with the southward IMF, the evidence is less convincing. The quantitative results that have been obtained are compared with current theoretical models of the reconnection process.

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“…Nishida and Nagayama (1973) offer further statistical evidence that the tail-lobe B increase propagates down the tail, appearing at later times as the moon's orbit is approached.…”

Section: Tail-lobe Magnetic Variationsmentioning

confidence: 74%

Section: Plasma and Magnetic Behavior Near The Neutral Sheetmentioning

confidence: 96%

Section: The Interplanetary Magnetic Field and Magnetospheric Convectionmentioning

confidence: 99%

Section: Plasma and Magnetic Behavior Near The Neutral Sheetmentioning

confidence: 99%

Section: Plasma and Magnetic Behavior Near The Neutral Sheetmentioning

confidence: 99%

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Observations of interactions between interplanetary and geomagnetic fields

Burch¹

1974

Reviews of Geophysics

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Substorm simulation: Insight into the mechanisms of initial brightening

2015

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Initial brightening of the aurora is an optical manifestation of the beginning of a substorm expansion and is accompanied by large‐amplitude upward field‐aligned currents (FACs). Based on global magnetohydrodynamic simulation, we suggest the possible generation mechanism of the upward FAC that may manifest the initial brightening. (1) A formation of the near‐Earth neutral line (NENL) releases the tension force that accelerates plasma earthward. (2) The earthward (perpendicular) flow is converted to a field‐aligned flow when flow braking takes place. (3) A high‐pressure region propagates earthward along a field line. (4) The off‐equatorial high‐pressure region pulls in and discharges ambient plasma, which generates a flow vorticity around it. (5) Region 1‐sense FAC is generated in the upper part of the off‐equatorial high‐pressure region. (6) The upward FAC is connected with the ionosphere in the center of the Harang discontinuity, causing the initial brightening. Additional dynamo is generated in the near‐Earth region, which transmits electromagnetic energy. Upward FAC that manifests the initial brightening seems to be necessarily originated in the near‐Earth off‐equatorial region where the magnitude of the perpendicular (diamagnetic) current is relatively small in comparison with that of the FAC. Near the equatorial plane, the perpendicular current is comparable to or larger than FAC so that a current line is diverted from a magnetic field line and that the FAC generated near the equatorial plane is not necessarily connected with the ionosphere. The proposed mechanism occurs regardless of the location of the NENL and may explain some of auroral forms.

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The dawn‐dusk length of the X line in the near‐Earth magnetotail: Geotail survey in 1994–2014

2015

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The dawn‐dusk length of the X line is investigated for magnetic reconnection in association with substorms in the near‐Earth magnetotail on the basis of the 21 year Geotail plasma sheet observations. The X line is identified as a simultaneous plasma flow Vx and magnetic field Bz reversal inside the ion‐electron decoupling region of magnetic reconnection. Forty‐four X lines can be found at XGSM = −20 to −31 RE in the magnetotail. The X line length is estimated on the basis of occurrence of magnetic reconnection. Characteristics of flows and fields are investigated for magnetic reconnection and tailward flow events to verify the obtained X line length. The dawn‐dusk length of the X line is most likely 6 RE with its center in the premidnight sector for moderate substorms. Hence, the magnetic reconnection site is mapped to approximately 1 h local time sector in the auroral ionosphere. The dawn‐dusk length of the X line is extended mainly dawnward for larger substorms.

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

Cited by 177 publications

References 22 publications

Observations of interactions between interplanetary and geomagnetic fields

Observations of interactions between interplanetary and geomagnetic fields

Substorm simulation: Insight into the mechanisms of initial brightening

The dawn‐dusk length of the X line in the near‐Earth magnetotail: Geotail survey in 1994–2014

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