Modeling the global magnetic field of the large‐scale Birkeland current systems

Tsyganenko, N. A.; Stern, David P.

doi:10.1029/96ja02735

Cited by 508 publications

(594 citation statements)

References 23 publications

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“…The detached arc was observed until $1620 UT, after which the emissions began to fade. An FUV image acquired on 18 June 2001 at 1530 UT and mapped to the GSM equatorial plane using the Tsyganenko and Stern [1996] magnetic field model is shown in Figure 1 (bottom). The detached proton arc is shown with an arrow in Figure 1 (left).…”

Section: Observationsmentioning

confidence: 99%

“…Figure 1, left) were observed in the 1500 -1700 MLT sector at $65°magnetic latitude (MLAT). The image is mapped to the Geocentric Solar Magnetospheric (GSM) equatorial plane using the Tsyganenko and Stern [1996] magnetic field model (Figure 1, right). In the equatorial plane, the detached arc extended between L $ 5 and L $ 8 in the afternoon sector.…”

Section: Observationsmentioning

confidence: 99%

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Modeling the electromagnetic ion cyclotron wave‐induced formation of detached subauroral proton arcs

2007

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[1] Detached dayside proton arcs have been recently observed at Earth with the IMAGE FUV instrument as subauroral arcs separated from the main oval and extending over several hours of local time in the afternoon sector. We investigate the mechanisms causing the proton precipitation during two subauroral arc events that occurred on 23 January 2001 and 18 June 2001. We employ our kinetic physics-based model coupled with a dynamic plasmasphere model and calculate the growth rate of electromagnetic ion cyclotron (EMIC) waves self-consistently with the evolving ring current H + , O + , and He + ion distributions. Modeled plasmaspheric densities agree well with in situ observations from geosynchronous LANL satellites and duskside plasmapause observations from IMAGE EUV but overestimate the drainage plume extent toward noon on 18 June. Global images of precipitating H + ions are obtained and compared with IMAGE observations of proton arcs. We find that EMIC waves are preferentially excited, and proton precipitation maximizes, within regions of spatial overlap of energetic ring current protons and dayside plasmaspheric plumes and along steep density gradients at the plasmapause. The model matches very well the temporal and spatial evolution of FUV observations on 23 January. The predicted location of the proton precipitation on 18 June extends a few hours westward of the observations, and an offset of 2 hours in the convection electric field is needed to reproduce well the evolution of the proton arc. This study indicates that cyclotron resonant wave-particle interactions are a viable mechanism for the generation of subauroral proton arcs.Citation: Jordanova, V. K., M. Spasojevic, and M. F. Thomsen (2007), Modeling the electromagnetic ion cyclotron wave-induced formation of detached subauroral proton arcs,

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Section: Observationsmentioning

confidence: 99%

Section: Observationsmentioning

confidence: 99%

Modeling the electromagnetic ion cyclotron wave‐induced formation of detached subauroral proton arcs

2007

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“…Figure 2 shows the position of the four Cluster spacecraft (true separations) and the Polar spacecraft during this interval in the GSM xz, xy and yz planes. The dotted lines show the model magnetic field lines using the Tsyganenko 1996 model (Tsyganenko and Stern, 1996) while the solid lines show the Cluster spacecraft paths, and the dashed lines show the Polar spacecraft's path. The Cluster spacecraft are all above the centre of the plasma sheet and in the post-midnight sector, and at −16 R E downtail at 18:00 UT (having later moved to −18 R E at 24:00 UT).…”

Section: Instrumentsmentioning

confidence: 99%

A joint Cluster and ground-based instruments study of two magnetospheric substorm events on 1 September 2002

et al. 2004

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Abstract. We present a coordinated ground-and spacebased multi-instrument study of two magnetospheric substorm events that occurred on 1 September 2002, during the interval from 18:00 UT to 24:00 UT. Data from the Cluster and Polar spacecraft are considered in combination with ground-based magnetometer and HF radar data. During the first substorm event the Cluster spacecraft, which were in the Northern Hemisphere lobe, are to the west of the main region affected by the expansion phase. Nevertheless, substorm signatures are seen by Cluster at 18:25 UT (just after the expansion phase onset as seen on the ground at 18:23 UT), despite the ∼5 R E distance of the spacecraft from the plasma sheet. The Cluster spacecraft then encounter an earthwardmoving diamagnetic cavity at 19:10 UT, having just entered the plasma sheet boundary layer. The second substorm expansion phase is preceded by pseudobreakups at 22:40 and 22:56 UT, at which time thinning of the near-Earth, L=6.6, plasma sheet occurs. The expansion phase onset at 23:05 UT is seen simultaneously in the ground magnetic field, in the magnetotail and at Polar's near-Earth position. The response in the ionospheric flows occurs one minute later. The second substorm better fits the near-Earth neutral line model for substorm onset than the cross-field current instability model.

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“…This indicates that the field line connected to the source region (i.e., BBF braking point) is located between ZYK and CHD, but closer to ZYK. From the T96 magnetic field model [Tsyganenko and Stern, 1996], the CHD and ZYK field lines map to X GSM $ À10.2 R E and X GSM $ À4.2 R E in the plasma sheet, respectively. The braking point in our case is closer to Earth than geocentric distances of 10 to 15 Re in the plasma sheet suggested by Shiokawa et al [1997].…”

Section: Mechanism For the Pi2 Pulsationmentioning

confidence: 99%

Pi2 pulsations in a small and strongly asymmetric plasmasphere

Kim¹

2005

J. Geophys. Res.

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[1] We study a Pi2 pulsation that occurred at $1520 UT on 29 August 2000. This Pi2 event was observed at ground stations from high (geomagnetic latitude $65°) to low latitudes ($17°) near midnight with an identical waveform and oscillated with a frequency of $11 mHz. During the event, a global image of the plasmasphere was obtained from the IMAGE satellite, and the location of the plasmapause was clearly identified. The plasmasphere was small and strongly asymmetric in longitude. The plasmapause was located at L $ 2.4, 3.8, and 3.3 near the duskside, midnight, and the dawnside, respectively. Using a magnetospheric mass density model constructed from the IMAGE satellite data and ground-based data, we examine whether the Pi2 pulsation observed inside the plasmasphere can be explained by a plasmaspheric cavity mode. We find that the frequency of 11 mHz is too low for a cavity mode in the plasmasphere. Thus the plasmaspheric cavity mode is not an appropriate model for our Pi2 event observed at midlatitudes and low latitudes. We discuss what determines its period and waveform inside such a small and asymmetric plasmasphere.Citation:

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Modeling the global magnetic field of the large‐scale Birkeland current systems

Cited by 508 publications

References 23 publications

Modeling the electromagnetic ion cyclotron wave‐induced formation of detached subauroral proton arcs

Modeling the electromagnetic ion cyclotron wave‐induced formation of detached subauroral proton arcs

A joint Cluster and ground-based instruments study of two magnetospheric substorm events on 1 September 2002

Pi2 pulsations in a small and strongly asymmetric plasmasphere

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