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Waters JE, Jackman CM, Whiter DK, Forsyth C, Fogg AR, Lamy L, Cecconi B, Bonnin X, Issautier K. A Perspective on Substorm Dynamics Using 10 Years of Auroral Kilometric Radiation Observations From Wind. JOURNAL OF GEOPHYSICAL RESEARCH. SPACE PHYSICS 2022; 127:e2022JA030449. [PMID: 36245707 PMCID: PMC9540659 DOI: 10.1029/2022ja030449] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Revised: 08/19/2022] [Accepted: 08/23/2022] [Indexed: 06/16/2023]
Abstract
We study 10 years (1995-2004 inclusive) of auroral kilometric radiation (AKR) radio emission data from the Wind spacecraft to examine the link between AKR and terrestrial substorms. We use substorm lists based on parameters including ground magnetometer signatures and geosynchronous particle injections as a basis for superposed epoch analyses of the AKR data. The results for each list show a similar, clear response of the AKR power around substorm onset. For nearly all event lists, the average response shows that the AKR power begins to increase around 20 min prior to expansion phase onset, as defined by the respective lists. The analysis of the spectral parameters of AKR bursts show that this increase in power is due to an extension of the source region to higher altitudes, which also precedes expansion phase onset by 20 min. Our observations show that the minimum frequency channel that observes AKR at this time, on average, is 60 kHz. AKR visibility is highly sensitive to observing spacecraft location, and the biggest radio response to substorm onset is seen in the 21:00-03:00 hr local time sector.
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Affiliation(s)
- J. E. Waters
- Space Environment Physics GroupSchool of Physics and AstronomyUniversity of SouthamptonSouthamptonUK
| | - C. M. Jackman
- DIAS Dunsink ObservatorySchool of Cosmic PhysicsDublin Institute for Advanced StudiesDublinIreland
| | - D. K. Whiter
- Space Environment Physics GroupSchool of Physics and AstronomyUniversity of SouthamptonSouthamptonUK
| | - C. Forsyth
- Department of Space and Climate PhysicsMSSLUCLDorkingUK
| | - A. R. Fogg
- DIAS Dunsink ObservatorySchool of Cosmic PhysicsDublin Institute for Advanced StudiesDublinIreland
| | - L. Lamy
- Observatoire de ParisLESIAPSL Research UniversityCNRSSorbonne UniversitéUniversity of ParisMeudonFrance
- LAMPythéasAix Marseille UniversitéCNRSCNESMarseilleFrance
| | - B. Cecconi
- Observatoire de ParisLESIAPSL Research UniversityCNRSSorbonne UniversitéUniversity of ParisMeudonFrance
| | - X. Bonnin
- Observatoire de ParisLESIAPSL Research UniversityCNRSSorbonne UniversitéUniversity of ParisMeudonFrance
| | - K. Issautier
- Observatoire de ParisLESIAPSL Research UniversityCNRSSorbonne UniversitéUniversity of ParisMeudonFrance
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2
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Ohtani S, Motoba T, Gjerloev JW, Frey HU, Mann IR, Chi PJ, Korth H. New Insights Into the Substorm Initiation Sequence From the Spatio-Temporal Development of Auroral Electrojets. JOURNAL OF GEOPHYSICAL RESEARCH. SPACE PHYSICS 2022; 127:e2021JA030114. [PMID: 35864908 PMCID: PMC9286795 DOI: 10.1029/2021ja030114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Revised: 04/04/2022] [Accepted: 05/14/2022] [Indexed: 06/15/2023]
Abstract
In the present study we examine three substorm events, Events 1-3, focusing on the spatio-temporal development of auroral electrojets (AEJs) before auroral breakup. In Events 1 and 2, auroral breakup was preceded by the equatorward motion of an auroral form, and the ground magnetic field changed northward and southward in the west and east of the expected equatorward flow, respectively. Provided that these magnetic disturbances were caused by local ionospheric Hall currents, this feature suggests that the equatorward flow turned both eastward and westward as it reached the equatorward part of the auroral oval. The auroral breakup took place at the eastward-turning and westward-turning branches in Events 1 and 2, respectively, and after the auroral breakup, the westward AEJ enhanced only on the same side of the flow demarcation meridian. The zonal flow divergence is considered as an ionospheric manifestation of the braking of an earthward flow burst in the near-Earth plasma sheet and subsequent dawnward and duskward turning. Therefore, in Events 1 and 2, the auroral breakup presumably mapped to the dawnward and duskward flow branches, respectively. Moreover, for Event 3, we do not find any pre-onset auroral or magnetic features that can be associated with an equatorward flow. These findings suggest that the braking of a pre-onset earthward flow burst itself is not the direct cause of substorm onset, and therefore, the wedge current system that forms at substorm onset is distinct from the one that is considered to form as a consequence of the flow braking.
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Affiliation(s)
- S. Ohtani
- Johns Hopkins University Applied Physics LaboratoryLaurelMDUSA
| | - T. Motoba
- Johns Hopkins University Applied Physics LaboratoryLaurelMDUSA
| | - J. W. Gjerloev
- Johns Hopkins University Applied Physics LaboratoryLaurelMDUSA
| | - H. U. Frey
- Space Sciences LaboratoryUniversity of CaliforniaBerkeleyCAUSA
| | | | - P. J. Chi
- Department of Earth and Space SciencesUniversity of CaliforniaLos AngelesCAUSA
| | - H. Korth
- Johns Hopkins University Applied Physics LaboratoryLaurelMDUSA
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3
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Orr L, Chapman SC, Gjerloev JW, Guo W. Network community structure of substorms using SuperMAG magnetometers. Nat Commun 2021; 12:1842. [PMID: 33758181 PMCID: PMC7988152 DOI: 10.1038/s41467-021-22112-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Accepted: 02/26/2021] [Indexed: 11/25/2022] Open
Abstract
Geomagnetic substorms are a global magnetospheric reconfiguration, during which energy is abruptly transported to the ionosphere. Central to this are the auroral electrojets, large-scale ionospheric currents that are part of a larger three-dimensional system, the substorm current wedge. Many, often conflicting, magnetospheric reconfiguration scenarios have been proposed to describe the substorm current wedge evolution and structure. SuperMAG is a worldwide collaboration providing easy access to ground based magnetometer data. Here we show application of techniques from network science to analyze data from 137 SuperMAG ground-based magnetometers. We calculate a time-varying directed network and perform community detection on the network, identifying locally dense groups of connections. Analysis of 41 substorms exhibit robust structural change from many small, uncorrelated current systems before substorm onset, to a large spatially-extended coherent system, approximately 10 minutes after onset. We interpret this as strong indication that the auroral electrojet system during substorm expansions is inherently a large-scale phenomenon and is not solely due to many meso-scale wedgelets.
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Affiliation(s)
- L Orr
- Centre for Fusion, Space and Astrophysics, University of Warwick, Coventry, UK.
| | - S C Chapman
- Centre for Fusion, Space and Astrophysics, University of Warwick, Coventry, UK
| | - J W Gjerloev
- Applied Physics Laboratory-John Hopkins University, Laurel, MD, USA
- Birkeland Centre, University of Bergen, Bergen, Norway
| | - W Guo
- School of Aerospace, Cranfield University, Cranfield, UK
- Alan Turing Institute, London, UK
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4
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Guineva V, Despirak I, Werner R, Bojilova R, Raykova L. Mid-latitude effects of “expanded” geomagnetic substorms: a case study. EPJ WEB OF CONFERENCES 2021. [DOI: 10.1051/epjconf/202125401004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The goal of this work is to examine the effects of the “expanded” or “high-latitude” substorms at mid-latitudes. These substorms are generated at auroral latitudes and propagate up to geomagnetic latitudes above ∼70° GMLat. They are usually observed during reccurent high-speed streams (HSS) from coronal holes. To identify the substorm activity, data from the networks IMAGE, SuperMAG and INTERMAGNET, and data from the all-sky cameras in Lovozero were used. To verify the interplanetary and geomagnetic conditions, data from the CDAWeb OMNI and from the WDC for geomagnetism at Kyoto were taken. We analyzed one substorm event on 20 February 2017 at ∼18:40 UT, it developed during HSS, in non-storm conditions. Some features of mid-latitude positive bays (MPB) at the European and Asian stations, and in particular at the Scandinavian meridian have been studied: the bay sign conversion from negative to positive values, the longitudinal and latitudinal extent of the MPB. The central meridian of the substorm was determined.
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Motoba T, Ohtani S, Claudepierre SG, Reeves GD, Ukhorskiy AY, Lanzerotti LJ. Dynamic Properties of Particle Injections Inside Geosynchronous Orbit: A Multisatellite Case Study. JOURNAL OF GEOPHYSICAL RESEARCH. SPACE PHYSICS 2020; 125:e2020JA028215. [PMID: 33282620 PMCID: PMC7685150 DOI: 10.1029/2020ja028215] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 07/28/2020] [Accepted: 08/29/2020] [Indexed: 06/12/2023]
Abstract
Four closely located satellites at and inside geosynchronous orbit (GEO) provided a great opportunity to study the dynamical evolution and spatial scale of premidnight energetic particle injections inside GEO during a moderate substorm on 23 December 2016. Just following the substorm onset, the four spacecraft, a LANL satellite at GEO, the two Van Allen Probes (also called "RBSP") at ~5.8 R E, and a THEMIS satellite at ~5.3 R E, observed substorm-related particle injections and local dipolarizations near the central meridian (~22 MLT) of a wedge-like current system. The large-scale evolution of the electron and ion (H, He, and O) injections was almost identical at the two RBSP spacecraft with ~0.5 R E apart. However, the initial short-timescale particle injections exhibited a striking difference between RBSP-A and -B: RBSP-B observed an energy dispersionless injection which occurred concurrently with a transient, strong dipolarization front (DF) with a peak-to-peak amplitude of ~25 nT over ~25 s; RBSP-A measured a dispersed/weaker injection with no corresponding DF. The spatiotemporally localized DF was accompanied by an impulsive, westward electric field (~20 mV m-1). The fast, impulsive E × B drift caused the radial transport of the electron and ion injection regions from GEO to ~5.8 R E. The penetrating DF fields significantly altered the rapid energy- and pitch angle-dependent flux changes of the electrons and the H and He ions inside GEO. Such flux distributions could reflect the transient DF-related particle acceleration and/or transport processes occurring inside GEO. In contrast, O ions were little affected by the DF fields.
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Affiliation(s)
- T. Motoba
- The Johns Hopkins University Applied Physics LaboratoryLaurelMDUSA
| | - S. Ohtani
- The Johns Hopkins University Applied Physics LaboratoryLaurelMDUSA
| | - S. G. Claudepierre
- Space Sciences DepartmentAerospace CorporationLos AngelesCAUSA
- Department of Atmospheric and Oceanic SciencesUniversity of CaliforniaLos AngelesCAUSA
| | | | - A. Y. Ukhorskiy
- The Johns Hopkins University Applied Physics LaboratoryLaurelMDUSA
| | - L. J. Lanzerotti
- Center for Solar‐Terrestrial ResearchNew Jersey Institute of TechnologyNewarkNJUSA
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Nishimura Y, Lyons LR, Gabrielse C, Weygand JM, Donovan EF, Angelopoulos V. Relative contributions of large-scale and wedgelet currents in the substorm current wedge. EARTH, PLANETS, AND SPACE : EPS 2020; 72:106. [PMID: 32728343 PMCID: PMC7373217 DOI: 10.1186/s40623-020-01234-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Accepted: 07/14/2020] [Indexed: 06/11/2023]
Abstract
We examined how much large-scale and localized upward and downward currents contribute to the substorm current wedge (SCW), and how they evolve over time, using the THEMIS all-sky imagers (ASIs) and ground magnetometers. One type of events is dominated by a single large-scale wedge, with upward currents over the surge and broad downward currents poleward-eastward of the surge. The other type of events is a composite of large-scale wedge and wedgelets associated with streamers, with each wedgelet having comparable intensity to the large-scale wedge currents. Among 17 auroral substorms with wide ASI coverage, the composite current type is more frequent than the single large-scale wedge type. The dawn-dusk size of each wedgelet is ~ 600 km in the ionosphere (~ 3.2 R E in the magnetotail, comparable to the flow channel size). We suggest that substorms have more than one type of SCW, and the composite current type is more frequent.
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Affiliation(s)
- Y. Nishimura
- Department of Electrical and Computer Engineering and Center for Space Physics, Boston University, Boston, MA USA
| | - L. R. Lyons
- Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, CA USA
| | | | - J. M. Weygand
- Department of Earth, Planetary and Space Sciences, University of California, Los Angeles, CA USA
| | - E. F. Donovan
- Department of Physics and Astronomy, University of Calgary, Calgary, AB Canada
| | - V. Angelopoulos
- Department of Earth, Planetary and Space Sciences, University of California, Los Angeles, CA USA
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7
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Fletcher LN, de Pater I, Orton GS, Hofstadter MD, Irwin PGJ, Roman MT, Toledo D. Ice Giant Circulation Patterns: Implications for Atmospheric Probes. SPACE SCIENCE REVIEWS 2020. [PMID: 32165773 DOI: 10.1007/s11214-019-0619-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Atmospheric circulation patterns derived from multi-spectral remote sensing can serve as a guide for choosing a suitable entry location for a future in situ probe mission to the Ice Giants. Since the Voyager-2 flybys in the 1980s, three decades of observations from ground- and space-based observatories have generated a picture of Ice Giant circulation that is complex, perplexing, and altogether unlike that seen on the Gas Giants. This review seeks to reconcile the various competing circulation patterns from an observational perspective, accounting for spatially-resolved measurements of: zonal albedo contrasts and banded appearances; cloud-tracked zonal winds; temperature and para-H2 measurements above the condensate clouds; and equator-to-pole contrasts in condensable volatiles (methane, ammonia, and hydrogen sulphide) in the deeper troposphere. These observations identify three distinct latitude domains: an equatorial domain of deep upwelling and upper-tropospheric subsidence, potentially bounded by peaks in the retrograde zonal jet and analogous to Jovian cyclonic belts; a mid-latitude transitional domain of upper-tropospheric upwelling, vigorous cloud activity, analogous to Jovian anticyclonic zones; and a polar domain of strong subsidence, volatile depletion, and small-scale (and potentially seasonally-variable) convective activity. Taken together, the multi-wavelength observations suggest a tiered structure of stacked circulation cells (at least two in the troposphere and one in the stratosphere), potentially separated in the vertical by (i) strong molecular weight gradients associated with cloud condensation, and by (ii) transitions from a thermally-direct circulation regime at depth to a wave- and radiative-driven circulation regime at high altitude. The inferred circulation can be tested in the coming decade by 3D numerical simulations of the atmosphere, and by observations from future world-class facilities. The carrier spacecraft for any probe entry mission must ultimately carry a suite of remote-sensing instruments capable of fully constraining the atmospheric motions at the probe descent location.
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Affiliation(s)
- Leigh N Fletcher
- 1School of Physics and Astronomy, University of Leicester, University Road, Leicester, LE1 7RH UK
| | - Imke de Pater
- 3Department of Astronomy, University of California, 501 Campbell Hall, Berkeley, CA 94720 USA
| | - Glenn S Orton
- 2Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109 USA
| | - Mark D Hofstadter
- 2Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109 USA
| | - Patrick G J Irwin
- 4Atmospheric, Oceanic and Planetary Physics, University of Oxford, Parks Road, Oxford, OX1 3PU UK
| | - Michael T Roman
- 1School of Physics and Astronomy, University of Leicester, University Road, Leicester, LE1 7RH UK
| | - Daniel Toledo
- 4Atmospheric, Oceanic and Planetary Physics, University of Oxford, Parks Road, Oxford, OX1 3PU UK
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8
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Liou K, Sotirelis T, Mitchell EJ. North-South Asymmetry in the Geographic Location of Auroral Substorms correlated with Ionospheric Effects. Sci Rep 2018; 8:17230. [PMID: 30467409 PMCID: PMC6250675 DOI: 10.1038/s41598-018-35091-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Accepted: 10/19/2018] [Indexed: 12/03/2022] Open
Abstract
Energetic particles of magnetospheric origin constantly strike the Earth’s upper atmosphere in the polar regions, producing optical emissions known as the aurora. The most spectacular auroral displays are associated with recurrent events called magnetospheric substorms (aka auroral substorms). Substorms are initiated in the nightside magnetosphere on closed magnetic field lines. As a consequence, it is generally thought that auroral substorms should occur in both hemispheres on the same field line (i.e., magnetically conjugated). However, such a hypothesis has not been verified statistically. Here, by analyzing 2659 auroral substorms acquired by the Ultraviolet Imager on board the NASA satellite “Polar”, we have discovered surprising evidence that the averaged location for substorm onsets is not conjugate but shows a geographic preference that cannot be easily explained by current substorm theories. In the Northern Hemisphere (NH) the auroral substorms occur most frequently in Churchill, Canada (~90°W) and Khatanga, Siberia (~100°E), up to three times as often as in Iceland (~22°W). In the Southern Hemisphere (SH), substorms occur more frequently over a location in the Antarctic ocean (~120°E), up to ~4 times more than over the Antarctic Continent. Such a large difference in the longitudinal distribution of north and south onset defies the common belief that substorms in the NH and SH should be magnetically conjugated. A further analysis indicates that these substorm events occurred more frequently when more of the ionosphere was dark. These geographic areas also coincide with regions where the Earth’s magnetic field is largest. These facts suggest that auroral substorms occur more frequently, and perhaps more intensely, when the ionospheric conductivity is lower. With much of the magnetotail energy coming from the solar wind through merging of the interplanetary and Earth’s magnetic field, it is generally thought that the occurrence of substorms is externally controlled by the solar wind and plasma instability in the magnetotail. The present study results provide a strong argument that the ionosphere plays a more active role in the occurrence of substorms.
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Affiliation(s)
- Kan Liou
- The Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland, 20723, USA.
| | - Thomas Sotirelis
- The Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland, 20723, USA
| | - Elizabeth J Mitchell
- The Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland, 20723, USA
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Lui ATY. Frozen-in condition for ions and electrons: implication on magnetic flux transport by dipolarizing flux bundles. GEOSCIENCE LETTERS 2018; 5:5. [PMID: 32215240 PMCID: PMC7081771 DOI: 10.1186/s40562-018-0104-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Accepted: 02/05/2018] [Indexed: 06/10/2023]
Abstract
The ability of dipolarizing flux bundles (DFBs) in transporting magnetic flux from the mid-tail reconnection site for near-Earth dipolarization is evaluated by two methods: the generalized Ohm's law and the concept of flux preserving and line preserving. From the generalized Ohm's law, the breakdown of the frozen-in condition (FIC) for ions is shown to be intimately related to that for electrons. When FIC is not satisfied for the ion fluid associated with energy conversion, it also implies the same for the electron fluid. When FIC holds, the plasma has the flux preserving property. It further guarantees that charged particles on a given magnetic field line will stay together on a magnetic field line at later times, i.e., line preserving. Conversely, when line preserving does not hold, flux preserving does not hold also. Previous detailed examination on the FIC for DFBs revealed that the majority of DFBs associated with energy conversion violate the FIC for the ion fluid. This implies that FIC does not hold for the electron fluid also. Furthermore, plasmas in substorm injections come from vastly different locations, violating the line preserving property and implying that FIC is broken for the magnetic flux tubes associated with substorm injection and dipolarization. These observations indicate that DFBs are not an effective agent to transport magnetic flux within the magnetosphere and further imply that mid-tail magnetic reconnection is rather ineffective in transporting magnetic flux for near-Earth dipolarization.
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10
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Nakamura R, Varsani A, Genestreti KJ, Le Contel O, Nakamura T, Baumjohann W, Nagai T, Artemyev A, Birn J, Sergeev VA, Apatenkov S, Ergun RE, Fuselier SA, Gershman DJ, Giles BJ, Khotyaintsev YV, Lindqvist P, Magnes W, Mauk B, Petrukovich A, Russell CT, Stawarz J, Strangeway RJ, Anderson B, Burch JL, Bromund KR, Cohen I, Fischer D, Jaynes A, Kepko L, Le G, Plaschke F, Reeves G, Singer HJ, Slavin JA, Torbert RB, Turner DL. Multiscale Currents Observed by MMS in the Flow Braking Region. JOURNAL OF GEOPHYSICAL RESEARCH. SPACE PHYSICS 2018; 123:1260-1278. [PMID: 29938154 PMCID: PMC5993344 DOI: 10.1002/2017ja024686] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Revised: 01/18/2018] [Accepted: 02/01/2018] [Indexed: 06/02/2023]
Abstract
We present characteristics of current layers in the off-equatorial near-Earth plasma sheet boundary observed with high time-resolution measurements from the Magnetospheric Multiscale mission during an intense substorm associated with multiple dipolarizations. The four Magnetospheric Multiscale spacecraft, separated by distances of about 50 km, were located in the southern hemisphere in the dusk portion of a substorm current wedge. They observed fast flow disturbances (up to about 500 km/s), most intense in the dawn-dusk direction. Field-aligned currents were observed initially within the expanding plasma sheet, where the flow and field disturbances showed the distinct pattern expected in the braking region of localized flows. Subsequently, intense thin field-aligned current layers were detected at the inner boundary of equatorward moving flux tubes together with Earthward streaming hot ions. Intense Hall current layers were found adjacent to the field-aligned currents. In particular, we found a Hall current structure in the vicinity of the Earthward streaming ion jet that consisted of mixed ion components, that is, hot unmagnetized ions, cold E × B drifting ions, and magnetized electrons. Our observations show that both the near-Earth plasma jet diversion and the thin Hall current layers formed around the reconnection jet boundary are the sites where diversion of the perpendicular currents take place that contribute to the observed field-aligned current pattern as predicted by simulations of reconnection jets. Hence, multiscale structure of flow braking is preserved in the field-aligned currents in the off-equatorial plasma sheet and is also translated to ionosphere to become a part of the substorm field-aligned current system.
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Affiliation(s)
- Rumi Nakamura
- Space Research InstituteAustrian Academy of SciencesGrazAustria
| | - Ali Varsani
- Space Research InstituteAustrian Academy of SciencesGrazAustria
| | | | - Olivier Le Contel
- Laboratoire de Physique des PlasmasCNRS/Ecole Polytechnique/UPMC Univ Paris 06/University Paris‐Sud/Observatoire de ParisParisFrance
| | - Takuma Nakamura
- Space Research InstituteAustrian Academy of SciencesGrazAustria
| | | | - Tsugunobu Nagai
- Earth and Planetary SciencesTokyo Institute of TechnologyTokyoJapan
| | - Anton Artemyev
- Department of Earth, Planetary and Space SciencesUniversity of CaliforniaLos AngelesCAUSA
| | | | - Victor A. Sergeev
- Earth's Physics DepartmentSt. Petersburg State UniversitySt. PetersburgRussia
| | - Sergey Apatenkov
- Earth's Physics DepartmentSt. Petersburg State UniversitySt. PetersburgRussia
| | - Robert E. Ergun
- Laboratory for Atmospheric and Space PhysicsUniversity of ColoradoBoulderCOUSA
| | | | | | | | | | | | - Werner Magnes
- Space Research InstituteAustrian Academy of SciencesGrazAustria
| | - Barry Mauk
- Applied Physics LaboratoryJohns Hopkins UniversityLaurelMDUSA
| | | | - Christopher T. Russell
- Department of Earth, Planetary and Space SciencesUniversity of CaliforniaLos AngelesCAUSA
| | - Julia Stawarz
- Department of PhysicsImperial College LondonLondonUK
| | - Robert J. Strangeway
- Department of Earth, Planetary and Space SciencesUniversity of CaliforniaLos AngelesCAUSA
| | - Brian Anderson
- Applied Physics LaboratoryJohns Hopkins UniversityLaurelMDUSA
| | | | | | - Ian Cohen
- Applied Physics LaboratoryJohns Hopkins UniversityLaurelMDUSA
| | - David Fischer
- Space Research InstituteAustrian Academy of SciencesGrazAustria
| | - Allison Jaynes
- Laboratory for Atmospheric and Space PhysicsUniversity of ColoradoBoulderCOUSA
| | | | - Guan Le
- NASA, Goddard Space Flight CenterGreenbeltMDUSA
| | | | | | | | - James A. Slavin
- Department of Climate and Space Sciences and EngineeringUniversity of MichiganAnn ArborMIUSA
| | - Roy B. Torbert
- Southwest Research InstituteSan AntonioTXUSA
- Institute for the Study of Earth, Oceans, and SpaceUniversity of New HampshireDurhamNHUSA
| | - Drew L. Turner
- Space Sciences DepartmentAerospace CorporationLos AngelesCAUSA
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11
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Borovsky JE, Valdivia JA. The Earth's Magnetosphere: A Systems Science Overview and Assessment. SURVEYS IN GEOPHYSICS 2018; 39:817-859. [PMID: 30956375 PMCID: PMC6428226 DOI: 10.1007/s10712-018-9487-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Accepted: 07/07/2018] [Indexed: 05/20/2023]
Abstract
A systems science examination of the Earth's fully interconnected dynamic magnetosphere is presented. Here the magnetospheric system (a.k.a. the magnetosphere-ionosphere-thermosphere system) is considered to be comprised of 14 interconnected subsystems, where each subsystem is a characteristic particle population: 12 of those particle populations are plasmas and two (the atmosphere and the hydrogen geocorona) are neutrals. For the magnetospheric system, an assessment is made of the applicability of several system descriptors, such as adaptive, nonlinear, dissipative, interdependent, open, irreversible, and complex. The 14 subsystems of the magnetospheric system are cataloged and described, and the various types of magnetospheric waves that couple the behaviors of the subsystems to each other are explained. This yields a roadmap of the connectivity of the magnetospheric system. Various forms of magnetospheric activity beyond geomagnetic activity are reviewed, and four examples of emergent phenomena in the Earth's magnetosphere are presented. Prior systems science investigations of the solar-wind-driven magnetospheric system are discussed: up to the present these investigations have not accounted for the full interconnectedness of the system. This overview and assessment of the Earth's magnetosphere hopes to facilitate (1) future global systems science studies that involve the entire interconnected magnetospheric system with its diverse time and spatial scales and (2) connections of magnetospheric systems science with the broader Earth systems science.
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Affiliation(s)
- Joseph E. Borovsky
- Center for Space Plasma Physics, Space Science Institute, Boulder, CO 80301 USA
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12
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Nakamura R, Nagai T, Birn J, Sergeev VA, Le Contel O, Varsani A, Baumjohann W, Nakamura T, Apatenkov S, Artemyev A, Ergun RE, Fuselier SA, Gershman DJ, Giles BJ, Khotyaintsev YV, Lindqvist PA, Magnes W, Mauk B, Russell CT, Singer HJ, Stawarz J, Strangeway RJ, Anderson B, Bromund KR, Fischer D, Kepko L, Le G, Plaschke F, Slavin JA, Cohen I, Jaynes A, Turner DL. Near-Earth plasma sheet boundary dynamics during substorm dipolarization. EARTH, PLANETS, AND SPACE : EPS 2017; 69:129. [PMID: 32009832 PMCID: PMC6961498 DOI: 10.1186/s40623-017-0707-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2017] [Accepted: 08/24/2017] [Indexed: 06/02/2023]
Abstract
We report on the large-scale evolution of dipolarization in the near-Earth plasma sheet during an intense (AL ~ -1000 nT) substorm on August 10, 2016, when multiple spacecraft at radial distances between 4 and 15 R E were present in the night-side magnetosphere. This global dipolarization consisted of multiple short-timescale (a couple of minutes) B z disturbances detected by spacecraft distributed over 9 MLT, consistent with the large-scale substorm current wedge observed by ground-based magnetometers. The four spacecraft of the Magnetospheric Multiscale were located in the southern hemisphere plasma sheet and observed fast flow disturbances associated with this dipolarization. The high-time-resolution measurements from MMS enable us to detect the rapid motion of the field structures and flow disturbances separately. A distinct pattern of the flow and field disturbance near the plasma boundaries was found. We suggest that a vortex motion created around the localized flows resulted in another field-aligned current system at the off-equatorial side of the BBF-associated R1/R2 systems, as was predicted by the MHD simulation of a localized reconnection jet. The observations by GOES and Geotail, which were located in the opposite hemisphere and local time, support this view. We demonstrate that the processes of both Earthward flow braking and of accumulated magnetic flux evolving tailward also control the dynamics in the boundary region of the near-Earth plasma sheet.Graphical AbstractMultispacecraft observations of dipolarization (left panel). Magnetic field component normal to the current sheet (BZ) observed in the night side magnetosphere are plotted from post-midnight to premidnight region: a GOES 13, b Van Allen Probe-A, c GOES 14, d GOES 15, e MMS3, g Geotail, h Cluster 1, together with f a combined product of energy spectra of electrons from MMS1 and MMS3 and i auroral electrojet indices. Spacecraft location in the GSM X-Y plane (upper right panel). Colorcoded By disturbances around the reconnection jets from the MHD simulation of the reconnection by Birn and Hesse (1996) (lower right panel). MMS and GOES 14-15 observed disturbances similar to those at the location indicated by arrows.
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Affiliation(s)
- Rumi Nakamura
- Space Research Institute, Austrian Academy of Sciences, Graz, Austria
| | | | | | | | - Olivier Le Contel
- Laboratoire de Physique des Plasmas, CNRS/Ecole polytechnique/UPMC Univ Paris 06/Univ. Paris-Sud/Observatoire de Paris, Paris, France
| | - Ali Varsani
- Space Research Institute, Austrian Academy of Sciences, Graz, Austria
| | | | - Takuma Nakamura
- Space Research Institute, Austrian Academy of Sciences, Graz, Austria
| | | | | | | | | | | | | | | | | | - Werner Magnes
- Space Research Institute, Austrian Academy of Sciences, Graz, Austria
| | - Barry Mauk
- Applied Physics Laboratory, Johns Hopkins University, Laurel, MD USA
| | | | | | - Julia Stawarz
- Department of Physics, Imperial College London, London, UK
| | | | - Brian Anderson
- Applied Physics Laboratory, Johns Hopkins University, Laurel, MD USA
| | | | - David Fischer
- Space Research Institute, Austrian Academy of Sciences, Graz, Austria
| | | | - Guan Le
- NASA, GSFC, Greenbelt, MD USA
| | | | - James A. Slavin
- Department of Climate and Space Sciences and Engineering, University of Michigan, Ann Arbor, MI USA
| | - Ian Cohen
- Applied Physics Laboratory, Johns Hopkins University, Laurel, MD USA
| | | | - Drew L. Turner
- Space Sciences Department, Aerospace Corporation, Los Angeles, CA USA
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Jackman CM, Thomsen MF, Mitchell DG, Sergis N, Arridge CS, Felici M, Badman SV, Paranicas C, Jia X, Hospodarksy GB, Andriopoulou M, Khurana KK, Smith AW, Dougherty MK. Field dipolarization in Saturn's magnetotail with planetward ion flows and energetic particle flow bursts: Evidence of quasi-steady reconnection. JOURNAL OF GEOPHYSICAL RESEARCH. SPACE PHYSICS 2015; 120:3603-3617. [PMID: 27570722 PMCID: PMC4981121 DOI: 10.1002/2015ja020995] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Revised: 04/01/2015] [Accepted: 04/01/2015] [Indexed: 05/20/2023]
Abstract
We present a case study of an event from 20 August (day 232) of 2006, when the Cassini spacecraft was sampling the region near 32 RS and 22 h LT in Saturn's magnetotail. Cassini observed a strong northward-to-southward turning of the magnetic field, which is interpreted as the signature of dipolarization of the field as seen by the spacecraft planetward of the reconnection X line. This event was accompanied by very rapid (up to ~1500 km s-1) thermal plasma flow toward the planet. At energies above 28 keV, energetic hydrogen and oxygen ion flow bursts were observed to stream planetward from a reconnection site downtail of the spacecraft. Meanwhile, a strong field-aligned beam of energetic hydrogen was also observed to stream tailward, likely from an ionospheric source. Saturn kilometric radiation emissions were stimulated shortly after the observation of the dipolarization. We discuss the field, plasma, energetic particle, and radio observations in the context of the impact this reconnection event had on global magnetospheric dynamics.
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Affiliation(s)
- C. M. Jackman
- School of Physics and AstronomyUniversity of SouthamptonSouthamptonUK
| | | | - D. G. Mitchell
- The Johns Hopkins University Applied Physics LaboratoryLaurelMarylandUSA
| | | | | | - M. Felici
- Department of PhysicsLancaster UniversityBailriggUK
- Mullard Space Science LaboratoryUniversity College LondonSurreyUK
- The Centre for Planetary Sciences at UCL/BirkbeckLondonUK
| | - S. V. Badman
- Department of PhysicsLancaster UniversityBailriggUK
| | - C. Paranicas
- The Johns Hopkins University Applied Physics LaboratoryLaurelMarylandUSA
| | - X. Jia
- Atmospheric, Oceanic and Space SciencesUniversity of MichiganAnn ArborMichiganUSA
| | - G. B. Hospodarksy
- Department of Physics and AstronomyUniversity of IowaIowa CityIowaUSA
| | - M. Andriopoulou
- Space Research InstituteAustrian Academy of SciencesGrazAustria
| | - K. K. Khurana
- Institute of Geophysics and Planetary PhysicsUniversity of CaliforniaLos AngelesCaliforniaUSA
| | - A. W. Smith
- School of Physics and AstronomyUniversity of SouthamptonSouthamptonUK
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Pothier NM, Weimer DR, Moore WB. Quantitative maps of geomagnetic perturbation vectors during substorm onset and recovery. JOURNAL OF GEOPHYSICAL RESEARCH. SPACE PHYSICS 2015; 120:1197-1214. [PMID: 26167445 PMCID: PMC4497481 DOI: 10.1002/2014ja020602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Accepted: 01/22/2015] [Indexed: 06/04/2023]
Abstract
UNLABELLED We have produced the first series of spherical harmonic, numerical maps of the time-dependent surface perturbations in the Earth's magnetic field following the onset of substorms. Data from 124 ground magnetometer stations in the Northern Hemisphere at geomagnetic latitudes above 33° were used. Ground station data averaged over 5 min intervals covering 8 years (1998-2005) were used to construct pseudo auroral upper, auroral lower, and auroral electrojet (AU*, AL*, and AE*) indices. These indices were used to generate a list of substorms that extended from 1998 to 2005, through a combination of automated processing and visual checks. Events were sorted by interplanetary magnetic field (IMF) orientation (at the Advanced Composition Explorer (ACE) satellite), dipole tilt angle, and substorm magnitude. Within each category, the events were aligned on substorm onset. A spherical cap harmonic analysis was used to obtain a least error fit of the substorm disturbance patterns at 5 min intervals up to 90 min after onset. The fits obtained at onset time were subtracted from all subsequent fits, for each group of substorm events. Maps of the three vector components of the averaged magnetic perturbations were constructed to show the effects of substorm currents. These maps are produced for several specific ranges of values for the peak |AL*| index, IMF orientation, and dipole tilt angle. We demonstrate an influence of the dipole tilt angle on the response to substorms. Our results indicate that there are downward currents poleward and upward currents just equatorward of the peak in the substorms' westward electrojet. KEY POINTS Show quantitative maps of ground geomagnetic perturbations due to substorms Three vector components mapped as function of time during onset and recovery Compare/contrast results for different tilt angle and sign of IMF Y-component.
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Affiliation(s)
- N M Pothier
- Department of Atmospheric and Planetary Sciences, Hampton UniversityHampton, Virginia, USA
- National Institute of AerospaceHampton, Virginia, USA
- Bradley Department of Electrical and Computer Engineering, Center for Space Science and Engineering Research, Virginia TechBlacksburg, Virginia, USA
- Department of Atmospheric, Oceanic, and Space Science, University of MichiganAnn Arbor, Michigan, USA
| | - D R Weimer
- National Institute of AerospaceHampton, Virginia, USA
- Bradley Department of Electrical and Computer Engineering, Center for Space Science and Engineering Research, Virginia TechBlacksburg, Virginia, USA
| | - W B Moore
- Department of Atmospheric and Planetary Sciences, Hampton UniversityHampton, Virginia, USA
- National Institute of AerospaceHampton, Virginia, USA
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Pressure gradient evolution in the near-Earth magnetotail at the arrival of BBFs. CHINESE SCIENCE BULLETIN-CHINESE 2014. [DOI: 10.1007/s11434-014-0618-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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16
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Forsyth C, Fazakerley AN, Rae IJ, J Watt CE, Murphy K, Wild JA, Karlsson T, Mutel R, Owen CJ, Ergun R, Masson A, Berthomier M, Donovan E, Frey HU, Matzka J, Stolle C, Zhang Y. In situ spatiotemporal measurements of the detailed azimuthal substructure of the substorm current wedge. JOURNAL OF GEOPHYSICAL RESEARCH. SPACE PHYSICS 2014; 119:927-946. [PMID: 26167439 PMCID: PMC4497475 DOI: 10.1002/2013ja019302] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Accepted: 01/13/2014] [Indexed: 06/01/2023]
Abstract
UNLABELLED The substorm current wedge (SCW) is a fundamental component of geomagnetic substorms. Models tend to describe the SCW as a simple line current flowing into the ionosphere toward dawn and out of the ionosphere toward dusk, linked by a westward electrojet. We use multispacecraft observations from perigee passes of the Cluster 1 and 4 spacecraft during a substorm on 15 January 2010, in conjunction with ground-based observations, to examine the spatial structuring and temporal variability of the SCW. At this time, the spacecraft traveled east-west azimuthally above the auroral region. We show that the SCW has significant azimuthal substructure on scales of 100 km at altitudes of 4000-7000 km. We identify 26 individual current sheets in the Cluster 4 data and 34 individual current sheets in the Cluster 1 data, with Cluster 1 passing through the SCW 120-240 s after Cluster 4 at 1300-2000 km higher altitude. Both spacecraft observed large-scale regions of net upward and downward field-aligned current, consistent with the large-scale characteristics of the SCW, although sheets of oppositely directed currents were observed within both regions. We show that the majority of these current sheets were closely aligned to a north-south direction, in contrast to the expected east-west orientation of the preonset aurora. Comparing our results with observations of the field-aligned current associated with bursty bulk flows (BBFs), we conclude that significant questions remain for the explanation of SCW structuring by BBF-driven "wedgelets." Our results therefore represent constraints on future modeling and theoretical frameworks on the generation of the SCW. KEY POINTS The substorm current wedge (SCW) has significant azimuthal structureCurrent sheets within the SCW are north-south alignedThe substructure of the SCW raises questions for the proposed wedgelet scenario.
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Affiliation(s)
- C Forsyth
- Mullard Space Science Laboratory, UCL Dorking, UK
| | | | - I J Rae
- Mullard Space Science Laboratory, UCL Dorking, UK
| | - C E J Watt
- Department of Meteorology, University of Reading Reading, UK
| | - K Murphy
- University of Alberta Edmonton, Alberta, Canada
| | - J A Wild
- Lancaster University Lancaster, UK
| | - T Karlsson
- Royal Institute of Technology Stockholm, Sweden
| | - R Mutel
- Department of Physics and Astronomy, University of Iowa Iowa City, Iowa, USA
| | - C J Owen
- Mullard Space Science Laboratory, UCL Dorking, UK
| | - R Ergun
- LASP, University of Colorado Boulder Boulder, Colorado, USA
| | - A Masson
- ESA/ESTEC Noordwijk, Netherlands
| | - M Berthomier
- Laboratoire de Physique des Plasmas, Observatoire de Saint Maur Paris, France
| | - E Donovan
- Department of Physics and Astronomy, University of Calgary Calgary, Alberta, Canada
| | - H U Frey
- Space Sciences Laboratory, University of California Berkeley, California, USA
| | - J Matzka
- National Space Institute, Technical University of Denmark Lyngby, Denmark
| | - C Stolle
- National Space Institute, Technical University of Denmark Lyngby, Denmark ; GFZ, German Centre for Geosciences Potsdam, Germany
| | - Y Zhang
- John Hopkins University Applied Physics Laboratory Laurel, Maryland, USA
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Ukhorskiy AY, Sitnov MI, Merkin VG, Artemyev AV. Rapid acceleration of protons upstream of earthward propagating dipolarization fronts. JOURNAL OF GEOPHYSICAL RESEARCH. SPACE PHYSICS 2013; 118:4952-4962. [PMID: 26167430 PMCID: PMC4497486 DOI: 10.1002/jgra.50452] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Revised: 06/27/2013] [Accepted: 07/13/2013] [Indexed: 06/03/2023]
Abstract
[1] Transport and acceleration of ions in the magnetotail largely occurs in the form of discrete impulsive events associated with a steep increase of the tail magnetic field normal to the neutral plane (Bz ), which are referred to as dipolarization fronts. The goal of this paper is to investigate how protons initially located upstream of earthward moving fronts are accelerated at their encounter. According to our analytical analysis and simplified two-dimensional test-particle simulations of equatorially mirroring particles, there are two regimes of proton acceleration: trapping and quasi-trapping, which are realized depending on whether the front is preceded by a negative depletion in Bz . We then use three-dimensional test-particle simulations to investigate how these acceleration processes operate in a realistic magnetotail geometry. For this purpose we construct an analytical model of the front which is superimposed onto the ambient field of the magnetotail. According to our numerical simulations, both trapping and quasi-trapping can produce rapid acceleration of protons by more than an order of magnitude. In the case of trapping, the acceleration levels depend on the amount of time particles stay in phase with the front which is controlled by the magnetic field curvature ahead of the front and the front width. Quasi-trapping does not cause particle scattering out of the equatorial plane. Energization levels in this case are limited by the number of encounters particles have with the front before they get magnetized behind it.
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Affiliation(s)
- AY Ukhorskiy
- The Johns Hopkins University Applied Physics Laboratory, LaurelMaryland, USA
| | - MI Sitnov
- The Johns Hopkins University Applied Physics Laboratory, LaurelMaryland, USA
| | - VG Merkin
- The Johns Hopkins University Applied Physics Laboratory, LaurelMaryland, USA
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18
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Ohtani S, Takahashi K, Zanetti LJ, Potemra TA, McEntire RW, Iijima T. Tail Current Disruption in the Geosynchronous Region. ACTA ACUST UNITED AC 2013. [DOI: 10.1029/gm064p0131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
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Mukai T, Yamamoto T, Machida S. Dynamics and Kinetic Properties of Plasmoids and Flux Ropes: GEOTAIL Observations. NEW PERSPECTIVES ON THE EARTH'S MAGNETOTAIL 2013. [DOI: 10.1029/gm105p0117] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
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20
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Zhou X, Russell CT, Mitchell DG. Three spacecraft observations of the geomagnetic tail during moderately disturbed conditions: Global perspective. ACTA ACUST UNITED AC 2013. [DOI: 10.1029/97ja00683] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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21
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Shepherd LS, Cassak PA. Guide field dependence of 3-D X-line spreading during collisionless magnetic reconnection. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/2012ja017867] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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22
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Kamide Y, Matsushita S. Simulation studies of ionospheric electric fields and currents in relation to field-aligned currents, 2. Substorms. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/ja084ia08p04099] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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23
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Farrugia CJ, Freeman MP, Burlaga LF, Lepping RP, Takahashi K. The Earth's magnetosphere under continued forcing: Substorm activity during the passage of an interplanetary magnetic cloud. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/92ja02351] [Citation(s) in RCA: 99] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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24
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Lui ATY, Meng CI, Akasofu SI. Search for the magnetic neutral line in the near-Earth plasma sheet 2. Systematic study of Imp 6 magnetic field observations. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/ja082i010p01547] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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25
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Kamide Y, Rostoker G. The spatial relationship of field-aligned currents and auroral electrojets to the distribution of nightside auroras. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/ja082i035p05589] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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26
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Baker DN, Pulkkinen TI, McPherron RL, Craven JD, Frank LA, Elphinstone RD, Murphree JS, Fennell JF, Lopez RE, Nagai T. CDAW 9 analysis of magnetospheric events on May 3, 1986: Event C. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/92ja02475] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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27
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Coroniti FV. Explosive tail reconnection: The growth and expansion phases of magnetospheric substorms. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/ja090ia08p07427] [Citation(s) in RCA: 119] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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28
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Vassiliadis D, Klimas AJ, Baker DN, Roberts DA. A description of the solar wind-magnetosphere coupling based on nonlinear filters. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/94ja02725] [Citation(s) in RCA: 165] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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29
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30
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Chun FK, Russell CT. The evolution of field-aligned currents as a function of substorm phase. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/91ja01018] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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31
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Ohtani S, Anderson BJ, Sibeck DG, Newell PT, Zanetti LJ, Potemra TA, Takahashi K, Lopez RE, Angelopoulos V, Nakamura R, Klumpar DM, Russell CT. A multisatellite study of a pseudo-substorm onset in the near-Earth magnetotail. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/93ja01421] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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33
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Rino CL, Wickwar VB, Banks PM, Akasofu SI, Rieger E. Incoherent scatter radar observations of westward electric fields, 2. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/ja079i031p04669] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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34
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Kivelson MG, Southwood DJ. Approximations for the study of drift boundaries in the magnetosphere. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/ja080i025p03528] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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35
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Birn J, Hesse M. The substorm current wedge and field-aligned currents in MHD simulations of magnetotail reconnection. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/90ja01762] [Citation(s) in RCA: 125] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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36
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Kokubun S, McPherron RL, Russell CT. Triggering of substorms by solar wind discontinuities. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/ja082i001p00074] [Citation(s) in RCA: 169] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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38
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Lassen K, Sharber JR, Winningham JD. The development of auroral and geomagnetic substorm activity after a southward turning of the interplanetary magnetic field following several hours of magnetic calm. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/ja082i032p05031] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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39
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Lui ATY, Hones EW, Venkatesan D, Akasofu SI, Bame SJ. Complete plasma dropouts at vela satellites during thinning of the plasma sheet. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/ja080i034p04649] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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40
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Feldman WC, Baker DN, Bame SJ, Birn J, Gosling JT, Hones EW, Schwartz SJ. Slow-mode shocks: A semipermanent feature of the distant geomagnetic tail. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/ja090ia01p00233] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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41
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Wallis DD, Anger CD, Rostoker G. The Spatial Relationship of Auroral Electrojets and Visible Aurora in the Evening Sector. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/ja081i016p02857] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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42
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Lui ATY, Meng CI, Akasofu SI. Search for the magnetic neutral line in the near-Earth plasma sheet, 1. Critical reexamination of earlier studies on magnetic field observations. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/ja081i034p05934] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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43
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Maezawa K. Magnetospheric convection induced by the positive and negativeZcomponents of the interplanetary magnetic field: Quantitative analysis using polar cap magnetic records. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/ja081i013p02289] [Citation(s) in RCA: 282] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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44
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Sugiura M. Identifications of the polar cap boundary and the auroral belt in the high-altitude magnetosphere: A model for field-aligned currents. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/ja080i016p02057] [Citation(s) in RCA: 107] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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45
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Pytte T, McPherron RL, Kivelson MG, West HI, Hones EW. Multiple-satellite studies of magnetospheric substorms: Radial dynamics of the plasma sheet. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/ja081i034p05921] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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46
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Tsunoda RT, Presnell RI, Potemra TA. The spatial relationship between the evening radar aurora and field-aligned currents. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/ja081i022p03791] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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47
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48
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Takahashi K, Ohtani SI, Anderson BJ. Statistical analysis of Pi 2 pulsations observed by the AMPTE CCE Spacecraft in the inner magnetosphere. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/95ja01849] [Citation(s) in RCA: 115] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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49
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Caan MN, McPherron RL, Russell CT. Solar wind and substorm-related changes in the lobes of the geomagnetic tail. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/ja078i034p08087] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Horning BL, McPherron RL, Jackson DD. Application of linear inverse theory to a line current model of substorm current systems. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/ja079i034p05202] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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