27 August 2001 substorm: Preonset phenomena, two main onsets, field‐aligned current systems, and plasma flow channels in the ionosphere and in the magnetosphere

Мишин, В. М.; Lunyushkin, S. B.; Wang, J. Y.; Моисеев, А. В.

doi:10.1002/2017ja023915

Cited by 14 publications

(7 citation statements)

References 134 publications

(200 reference statements)

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“…4). This location corresponds to the ionospheric projection of the mantle (Newell and Meng, 1992). This increase in antisunward convection might be caused by the enhancement of the dayside reconnection under negative IMF Bz.…”

Section: Preonset Phenomena In the Data Of Ground-based Observationsmentioning

confidence: 73%

Polar substorm on 7 December 2015: preonset phenomena and features of auroral breakup

Safargaleev

Kozlovsky²,

Mitrofanov

2020

Ann. Geophys.

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Abstract. Comprehensive analysis of a moderate 600 nT substorm was performed using simultaneous optical observations inside the auroral oval and in the polar cap, combined with data from satellites, radars, and ground magnetometers. The onset took place near the poleward boundary of the auroral oval that is not typical for classical substorms. The substorm onset was preceded by two negative excursions of the interplanetary magnetic field (IMF) Bz component, with a 1 min interval between them, two enhancements of the antisunward convection in the polar cap with the same time interval, and 15 min oscillations in the geomagnetic H component in the auroral zone. The distribution of the pulsation intensity along meridian has two local maxima, namely at the equatorial and poleward boundaries of the auroral oval, where pulsations occurred in the out-of-phase mode resembling the field line resonance. At the initial stage, the auroral breakup developed as the auroral torch stretched and expanded poleward along the meridian. Later it took the form of the large-scale coiling structure that also distinguishes the considered substorm from the classical one. Magnetic, radar, and the Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE) satellite data show that, before the collapse, the coiling structure was located between two field-aligned currents, namely downward at the poleward boundary of structure and upward at the equatorial boundary. The set of GEOTAIL satellites and ground data fit to the near-tail current disruption scenario of the substorm onset. We suggest that the 15 min oscillations might play a role in the substorm initiation.

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Section: Preonset Phenomena In the Data Of Ground-based Observationsmentioning

confidence: 73%

Polar substorm on 7 December 2015: preonset phenomena and features of auroral breakup

Safargaleev

Kozlovsky²,

Mitrofanov

2020

Ann. Geophys.

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“…phase was observed by Mishin et al (2017). The patch in the ESR data was associated with a southward displacement of the poleward boundary of the westward electrojet (Fig.2b).…”

mentioning

confidence: 83%

Polar substorm on 7 December 2015: pre-onset phenomena and features of auroral breakup

Safargaleev¹,

Kozlovsky²,

Mitrofanov³

2019

Preprint

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Abstract. Comprehensive analysis of a moderate 600-nT substorm was performed with using simultaneous optical observations inside the auroral oval and in the polar cap, combined with data from satellites, radars, and ground magnetometers. The onset took place near the poleward boundary of the auroral oval that is not typical for classical substorms. The substorm onset was preceded by two negative excursions of the IMF Bz component with 15-min interval between them, two enhancements of the antisunward convection in the polar cap with the same repetition period, and 15-minute oscillations in geomagnetic H-component in the auroral zone. The distribution of the pulsation intensity along meridian has two local maxima – at equatorial and poleward boundaries of the auroral oval where pulsations occurred in the out-of-phase mode resembling the field-line resonance. At initial stage, the auroral breakup developed as auroral torch stretching and expanding poleward along the meridian. Some later it took a form of the large-scale coiling structure that also distinguishes the considered substorm from classical one. Magnetic, radar and AMPERE satellite data show that before the collapse the coiling structure was located between two field-aligned currents: downward at poleward boundary of structure and upward at equatorial boundary. The set of GEOTAIL satellite and ground data fits to the near-tail current disruption scenario of the substorm onset. We suggest that the 15-min oscillations might play a role in the substorm initiation.

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“…Those are not resolved in the data of pulsations with periods about and greater than the time interval, τ , between the two onsets. For example, at the start of the 27 August 2001 substorm (Baker et al, 2002; Mishin et al, 2013, 2017), this interval was τ = 2 min. The onsets could be specified using the short‐period ( Т < 10 s) component of Pi1B with a shorter duration.…”

Section: Introductionmentioning

confidence: 99%

“…The EP onset or simply onset, also known as substorm breakup, features the dipolarization, the geomagnetic tail contraction related to the release of the magnetic energy accumulated during the growth phase, and the fast decrease in the polar cap magnetic flux. These processes result in rapidly growing field‐aligned currents (FACs) and the intensified auroral activity (Mishin et al, 2017; Stephens et al, 2019). The EP onset is normally determined by observing the start of the geomagnetic pulsation (Pi2) train at high and middle latitudes, as well as by the auroral intensification (Kangas, 1998; Pudovkin et al, 1976; Troitskaya & Guglielmi, 1967).…”

Section: Introductionmentioning

confidence: 99%

Burst Geomagnetic Pulsations as Indicators of Substorm Expansion Onsets During Storms

et al. 2020

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We report on the dynamics of field-aligned currents (FACs), broadband geomagnetic pulsations, and airglow obtained from the Irkutsk (IRK), Mondy (MND), and Borok (BOX) midlatitude geomagnetic observatories and the Tory (TOR) optical observatory during storm substorms. For the first time, using the short duration, Δt < 0.5 min, high-frequency component of the burst pulsations (Pi1B), we determined the substorm double expansion phase (EP) onsets <5 min apart, which is hardly possible by means of the low-frequency (periods of 2-5 min) Psc/PiB pulsations. We argue that the observed burst pulsations are the result of prompt changes in the solar wind dynamic pressure and/or the current circuit related to the westward electrojet. Each pulsed source can excite short bursts of broadband electromagnetic modes of the ionospheric Alfvén resonator in the range of short-period pulsations with a periodic resonance structure of the spectrum characteristic of the observed Pi1B/Psc pulsations. Plain Language Summary We explored geomagnetic and optical midlatitude observations during storms. In addition to the common low-frequency (periods of 2-5 min) Psc/PiB pulsations, we used the short-period part (Pi1B) of burst pulsations with T < 10 s that allowed us to determine not only isolated substorm expansion onsets but also double substorm onsets and series of onsets of short substorm activations or pseudobreakups during storms. This is hardly possible with the commonly used long-period pulsations (Pi2, Pi3) that are problematic due to their long duration.

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27 August 2001 substorm: Preonset phenomena, two main onsets, field‐aligned current systems, and plasma flow channels in the ionosphere and in the magnetosphere

Cited by 14 publications

References 134 publications

Polar substorm on 7 December 2015: preonset phenomena and features of auroral breakup

Polar substorm on 7 December 2015: preonset phenomena and features of auroral breakup

Polar substorm on 7 December 2015: pre-onset phenomena and features of auroral breakup

Burst Geomagnetic Pulsations as Indicators of Substorm Expansion Onsets During Storms

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