Relationship between PC index and magnetospheric substorms observed under conditions of northward IMF

Трошичев, О. А.; Podorozhkina, Nataly; Janzhura, Alexander

doi:10.1016/j.jastp.2011.08.003

Cited by 7 publications

(9 citation statements)

References 19 publications

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“…This may also contribute to injection of ring current particles as proposed by Kuznetsova and Laptukhov [] and Troshichev et al . [, ].…”

Section: Discussionmentioning

confidence: 99%

“…On the other hand, Kuznetsova and Laptukhov [] and Troshichev et al . [, ] regarded the storm on 21–22 January 2005 as a usual phenomenon since it occurred under the influence of a large interplanetary electric field E m. The unusual Dst dynamics was explained by a great enhancement of the geoeffective E m with the initial input from the southward IMF B z and the succeeding input from the azimuthal IMF B y component against the background of the very high solar wind speed ( V sw > 800 km/s). In addition, McKenna‐Lawlor et al .…”

Section: Introductionmentioning

confidence: 99%

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Anomalous dynamics of the extremely compressed magnetosphere during 21 January 2005 magnetic storm

et al. 2014

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The dayside magnetosphere and proton radiation belt were analyzed during unusual magnetic storm on 21 January 2005. We have found that from 1712 to 2400 UT, the subsolar magnetopause was continuously located inside geosynchronous orbit due to strong compression. The compression was extremely strong from 1846 to 2035 UT when the dense plasma of fast erupting filament produced the solar wind dynamic pressure that peaked up to > 100 nPa, and during the first time, the upstream solar wind was observed at geosynchronous orbit for almost 2 h. Under the extreme compression, the outer magnetosphere at L > 5 was pushed inward, and the outer radiation belt particles moved earthward, became adiabatically accelerated, and accumulated in the inner magnetosphere at L < 4 that produced the intensified ring current with an exceptionally long lifetime. The observations were compared with predictions of various empirical and first-principles models. All the models failed to predict the magnetospheric dynamics under the extreme compression when the minimal magnetopause distance was estimated to be~3 RE. The inconsistencies might result from distortions of plasma measurements by extreme heliospheric conditions consisting in very fast solar wind streams and intense fluxes of solar energetic particles. We speculated that anomalous dynamics of the magnetosphere could be well described by the models if the He abundance in the solar wind was assumed to be > 20%, which is well appropriate for erupting filaments and which is in agreement with the upper 27% threshold for the He/H ratio obtained from Cluster measurements.

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“…This may also contribute to injection of ring current particles as proposed by Kuznetsova and Laptukhov [] and Troshichev et al . [, ].…”

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Anomalous dynamics of the extremely compressed magnetosphere during 21 January 2005 magnetic storm

et al. 2014

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“…The conclusion was made that occurrence of such substorms implies a large amount of energy remained in the tail even under northward IMF impact on the magnetosphere. Troshichev et al (2011) tested the substorms examined by Lee et al (2010) in their relation to interplanetary electric field E KL and the PC index. It turned out that values E KL and PC in all cases were in excess of the threshold level~1.5 mV/m, which is required for the ordinary substorm development.…”

Section: Discussionmentioning

confidence: 99%

“…As this takes place, the PC index, characterizing the polar cap magnetic activity affected by E KL , demonstrates the evident relation to the substorm onset. The conclusion was made by Troshichev et al (2011) that substorms considered by Lee et al (2010), as exclusive events, turn out to be a quite ordinary phenomena, if the proper coupling function E KL and the corresponding PC index are taken into examination.…”

Section: Discussionmentioning

confidence: 99%

PC index as a proxy of the solar wind energy that entered into the magnetosphere: 2. Relation to the interplanetary electric field E KL before substorm onset

Troshichev

Sormakov

2015

Earth Planet Sp

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This paper (the second of a series) presents the results of statistical investigation of relationship between the interplanetary electric field E KL and the Polar Cap (PC) index in case of magnetic substorms (1998)(1999)(2000)(2001), which have been analyzed in Troshichev et al. (J. Geophys. Res. Space Physics, 119, 2014). The PC index is directly related to the E KL field variations on interval preceding the substorm sudden onset (SO): correlation R > 0.5 is typical of more than 90 % of isolated substorms, 80 % of expanded substorms, and 99 % of events with coordinated E KL and PC jumps. The low or negative correlation observing in~10 % of examined substorms suggests that the solar wind flow measured by the Advanced Composition Explorer (ACE) spacecraft in the Lagrange point L1 did not encounter the magnetosphere in these cases. Examination of the delay times ΔT in the response of PC index to E KL variations provides the following results: (1) delay times do not depend on separate solar wind parameters, such as solar wind speed V X and interplanetary magnetic field (IMF) B Z component, contrary to general conviction, (2) the ΔT value is best controlled by the E KL field growth rate (dE KL /dt), (3) the lower ΔT limit (5-7 min is attained under conditions of the higher E KL growth rate, and (4) the PC index provides the possibility to verify the solar wind flow transportation time from ACE position (where the solar wind speed is estimated) to magnetosphere. These results, in combination with data testifying that the substorm onsets are related to the PC precursors, demonstrate that the PC index is an adequate ground-based indicator of the solar wind energy incoming into the magnetosphere.

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“…Used in: Frank‐Kamenetsky and Troshichev [], Troshichev [], Troshichev and Janzhura [, ], Troshichev et al . [, , , , ]. 5.…”

Section: Pc Index Proceduresmentioning

confidence: 99%

The Polar Cap index: A critical review of methods and a new approach

Stauning

2013

JGR Space Physics

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[1] The Polar Cap (PC) index introduced by Troshichev and Andrezen (1985) is derived from polar magnetic variations and is mainly a measure of the intensity of the transpolar ionospheric currents. These currents relate to the polar cap antisunward ionospheric plasma convection driven by the dawn-dusk electric fields, which in turn are generated by the interaction of the solar wind with the Earth's magnetosphere. Coefficients to calculate PCN and PCS index values from polar magnetic variations recorded at Thule and Vostok, respectively, have been derived by several different procedures in the past. The PCN index is found in seven different versions while the PCS index is found in five different versions in past publications. Recent publications (in 2011 and 2012) still convey three different PCN and two different PCS indices. The presentation here discusses the principal differences between the various PC index procedures and provides comparisons between coefficient and index values derived using the different procedures. Finally, a new approach to define a simplified PC index procedure is outlined.

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Relationship between PC index and magnetospheric substorms observed under conditions of northward IMF

Cited by 7 publications

References 19 publications

Anomalous dynamics of the extremely compressed magnetosphere during 21 January 2005 magnetic storm

Anomalous dynamics of the extremely compressed magnetosphere during 21 January 2005 magnetic storm

PC index as a proxy of the solar wind energy that entered into the magnetosphere: 2. Relation to the interplanetary electric field E KL before substorm onset

The Polar Cap index: A critical review of methods and a new approach

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