Triggering of substorm expansion by the IMF directional discontinuities: Time delay analysis

Сергеев, В. А.; Dmitrieva, N. P.; Barkova, E. S.

doi:10.1016/0032-0633(86)90023-1

Cited by 42 publications

(29 citation statements)

References 21 publications

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“…These observational results, consistent with the early study by Glassmeier et al (1988), also suggest that the magnetic enhancements at geostationary orbit and on the ground can be caused by the SCW formation. According to Shiokawa et al (1998), the SCW formation can be due to braking of fast flows or bursty bulk flows resulting from magnetic reconnection in the near-Earth magnetotail. Recently, Kepko et al (2004) showed that the onsets of both nightside Pi2 pulsations and magnetic bay variations were simultaneous with auroral brightening.…”

Section: Discussionmentioning

confidence: 99%

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THEMIS observations of double-onset substorms and their association with IMF variations

et al. 2011

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Abstract. On 16 July 2008, two pairs of consecutive bursts of Pi2 pulsations were recorded simultaneously across the THEMIS ground-based observatory system. Wavelet transformation reveals that for each high-latitude pair, the dominant frequency of the first burst is higher than that of the second. But at low latitudes, the dominant frequency does not change. It is suggested that both pairs result from fast magnetospheric cavity waves with the second burst also containing shear Alfvén waves. INTERMAGNET magnetograms at auroral latitudes showed magnetic variations affected by two recurrent electrojets for each pair. The ground-based magnetometers and those at geostationary orbit sensed magnetic perturbations consistent with the formation of the substorm current wedge. Four consecutive enhancements of energetic electron and ion fluxes detected by the THEMIS probes in the dayside magnetosphere appeared in the later afternoon and then in the early afternoon. The horizontal magnetic variation vectors had vortex patterns similar to those induced by the upward and downward field-aligned currents during substorm times. The hodogram at mid-L stations had a polarization pattern similar to the one induced by the substorm current wedge for each Pi2 burst. The mapping of ground Pi2 onset timing to the interplanetary magnetic field (IMF) observations shows that they appear under two cycles of north-to-south and then north variation. CLUSTER 4 in the south lobe observed wave-like magnetic fluctuations, probably driven by near-Earth reconnection, similar to those on the ground. These two observations are consistent with the link of double-onset substorms to magnetotail reconnection externally triggered by IMF variations.

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Section: Discussionmentioning

confidence: 99%

“…On the other hand, earlier studies (Caan et al, 1975;McPherron et al, 1986;Sergeev et al, 1986) reported that substorm onsets are associated with northward turning of the IMF. Subsequent work (e.g.…”

Section: Introductionmentioning

confidence: 87%

THEMIS observations of double-onset substorms and their association with IMF variations

et al. 2011

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“…Spontaneous (Henderson et al 1996) onsets and externally triggered (McPherron et al 1986;Lyons 1996) onsets (stimulated by sudden impulses, northward turnings or rotational discontinuities (Sergeev et al 1990)) may exhibit different destabilization scenarios (Lyons 1995). It is possible, e.g., that external triggers result in an NENL-like path to substorm onset, whereas spontaneous onset substorms follow the CD paradigm prescription.…”

Section: Primary Objective: Substorm Causalitymentioning

confidence: 97%

The THEMIS Mission

2008

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The Time History of Events and Macroscale Interactions during Substorms (THEMIS) mission is the fifth NASA Medium-class Explorer (MIDEX), launched on February 17, 2007 to determine the trigger and large-scale evolution of substorms. The mission employs five identical micro-satellites (hereafter termed "probes") which line up along the Earth's magnetotail to track the motion of particles, plasma and waves from one point to another and for the first time resolve space-time ambiguities in key regions of the magnetosphere on a global scale. The probes are equipped with comprehensive in-situ particles and fields instruments that measure the thermal and super-thermal ions and electrons, and electromagnetic fields from DC to beyond the electron cyclotron frequency in the regions of interest. The primary goal of THEMIS, which drove the mission design, is to elucidate which magnetotail process is responsible for substorm onset at the region where substorm auroras map (∼10 R E ): (i) a local disruption of the plasma sheet current (current disruption) or (ii) the interaction of the current sheet with the rapid influx of plasma emanating from reconnection at ∼25 R E . However, the probes also traverse the radiation belts and the dayside magnetosphere, allowing THEMIS to address additional baseline objectives, namely: how the radiation belts are energized on time scales of 2-4 hours during the recovery phase of storms, and how the pristine solar wind's interaction with upstream beams, waves and the bow shock affects Sun-Earth coupling. THEMIS's open data policy, platform-independent dataset, open-source analysis software, automated plotting and dissemination of data within hours of receipt, dedicated ground-based observatory network and strong links to ancillary space-based and ground-based programs. promote a grass-roots integration of relevant NASA, NSF and international assets in the context of an international Heliophysics Observatory over the next decade. The mission has demonstrated spacecraft and mission design strategies ideal for Constellation-class missions and its science is complementary to Cluster and MMS. THEMIS, the first NASA micro-satellite constellation, is a technological pathfinder for future Sun-Earth Connections missions and a stepping stone towards understanding Space Weather.V. Angelopoulos ( ) IGPP/ESS UCLA,

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“…In doing so, we took into account the time lag r due to the separation between the solar wind (SW) monitor and the magnetospheric (MS) spacecraft. Another inherent simplification of (1) is that it ignores possible effects of oblique disturbance boundaries in the solar wind, which can lead to significant errors in the calculated delay times, especially when the solar wind monitoring spacecraft is far from the Sun-Earth line [e.g., Sergeev et al, 1986]. However, with only one spacecraft in the solar wind, there exist no simple operational method of taking that effect into account, so that using the simplest procedure based on (1) appears to be the only feasible choice.…”

Section: Solar Wind Datamentioning

confidence: 99%

Global configuration of the magnetotail current sheet as derived from Geotail, Wind, IMP 8 and ISEE 1/2 data

Tsyganenko¹,

Karlsson²,

Kokubun³

et al. 1998

J. Geophys. Res.

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Triggering of substorm expansion by the IMF directional discontinuities: Time delay analysis

Cited by 42 publications

References 21 publications

THEMIS observations of double-onset substorms and their association with IMF variations

THEMIS observations of double-onset substorms and their association with IMF variations

The THEMIS Mission

Global configuration of the magnetotail current sheet as derived from Geotail, Wind, IMP 8 and ISEE 1/2 data

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