The energetic ion substorm injection boundary

López, Ramón; Sibeck, D. G.; McEntire, R. W.; Krimigis, S. M.

doi:10.1029/ja095ia01p00109

Cited by 109 publications

(93 citation statements)

References 38 publications

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“…The sudden increase in the particle flux following a slow decrease near local midnight at geosynchronous orbit is normally described as particle injection and is a typical signature of the magnetospheric substorm. For a satellite located inside the injection region the particle injection for all energy channels is observed to occur almost simultaneously which is called a dispersionless injection (Lopez et al, 1990). For sawtooth events, the dispersionless particle injection is observed with a wider local time range than that of a typical isolated substorm which is confined to near local midnight only.…”

Section: Introductionmentioning

confidence: 95%

Statistical analysis of ionospheric potential patterns for isolated substorms and sawtooth events

2006

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Abstract. We present here results which contrast isolated substorms with individual sawtooth events. Sawtooth events are defined as quasi-periodic, large-amplitude oscillations in the energetic particle flux with a periodicity of 2-4 h observed at the geosynchronous orbit. Sawtooth events have several similarities to isolated substorms leading therefore, to different opinions about whether sawtooth events are just an intense periodic form of substorms or if they deserve a category of their own. To help resolve this, we examine the ionospheric potential patterns in the northern polar region for isolated substorms and sawtooth events using the assimilative mapping of ionospheric electrodynamics (AMIE) technique. First we show a statistical analysis of isolated substorm potential patterns. In order to examine the seasonal variation, isolated substorms are identified by mid-latitude positive bay in the north-south geomagnetic perturbation in each season, respectively. Superposed epoch analysis (SEA) is applied to obtain the typical polar potential patterns for each season. By examining the time evolution of the potential patterns and cross polar cap potential (CPCP) for isolated substorms during each season, we find only subtle seasonal variations in the results obtained using the AMIE analysis. This provides a basis for comparison with sawtooth events in the next step. From the averaged potential patterns of 213 isolated substorms and those of 184 individual sawtooth events, we find the sawtooth events show signatures similar to subtorms: the DP 1 potential pattern develops and dominates the polar region after the onset. However, the DP 1 potential cell of sawtooth events encompasses a larger area than that of isolated substorms. Moreover, the CPCP of sawtooth is stronger than that of isolated substorms. It is also shown that the sawtooth events displays greater variability between individual events than isolated substorms. We conclude that in terms of ionospheric electrodynamics, the sawtoothe events have features that are similar to those of isolates substorms, though larger in spatial extent and in magnitude.

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Section: Introductionmentioning

confidence: 95%

Statistical analysis of ionospheric potential patterns for isolated substorms and sawtooth events

2006

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“…the premidnight sector [Lopez et al, 1990], where auroral breakups most frequently occur [Craven and Frank, 1991;Liou et a/.,this issue, and are associated with the formation of substorm current wedge, which also frequently takes place in the premidnight sector [Lopez et al, 1990]. This close association of the substorm injections with many substorm onset signatures has made the injections one of the most reliable substorm onset indicators.…”

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confidence: 99%

Particle injections with auroral expansions

Liou¹,

Meng²,

Newell³

et al. 2001

J. Geophys. Res.

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“…(b) innermost limit of substorm-related magnetic field changes and particle injection resulting from disruption of the cross-tail current sheet (Lopez et al, 1990); (c) narrow MLT channels of enhanced electric field in the nightside magnetosphere (probably related to the dipolarization process) along which particles rapidly penetrate down to low L-shells (Li et al, 1998);…”

Section: Introductionmentioning

confidence: 99%

Two types of ion spectral gaps in the quiet inner magnetosphere: Interball-2 observations and modeling

et al. 2002

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Abstract. We analyse measurements of ion spectral gaps (ISGs) observed by the ION particle spectrometer on board the Interball-2 satellite. The ISG represents a sharp decrease in H + flux at a particular narrow energy range. ISGs are practically always observed in the inner magnetosphere in a wide MLT range during quiet times. Clear examples of ISG in the morning, dayside, evening and nightside sectors of the magnetosphere are selected for detailed analysis and modeling. To obtain a model ISG, the trajectories of ions drifting in the equatorial plane from their nightside source to the observation point were computed for the energy range 0.1-15 keV. Three global convection models (McIlwain, 1972(McIlwain, , 1986Volland, 1973;Stern, 1975) were tested to reproduce the observed ISGs in all MLT sectors. Qualitative agreement is obtained for all three models, but the better agreement for quiet times is reached with the McIlwain (1972) convection model. It is shown that the ISGs observed by the ION spectrometer throughout the inner magnetosphere are the result of superposition of the two effects, already described in the literature (e.g. McIlwain, 1972;Shirai et al., 1997), but acting under different conditions. Also, the role of particle source location on the model gaps is investigated. It may be concluded that despite the evidence of large amplitude and directional local fluctuations of electric fields in the inner magnetosphere (Quinn et al., 1999), the existence of a stationary average convection pattern is confirmed by this modeling. This fact directly follows from observations of ISGs and from a good agreement of observations with modeled gaps calculated in the frames of adiabatic theory for a stationary (average) convection pattern.

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The energetic ion substorm injection boundary

Cited by 109 publications

References 38 publications

Statistical analysis of ionospheric potential patterns for isolated substorms and sawtooth events

Statistical analysis of ionospheric potential patterns for isolated substorms and sawtooth events

Particle injections with auroral expansions

Two types of ion spectral gaps in the quiet inner magnetosphere: Interball-2 observations and modeling

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