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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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Modeling of Magnetospheres of Terrestrial Exoplanets in the Habitable Zone around G-Type Stars. UNIVERSE 2022. [DOI: 10.3390/universe8040231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Using a paraboloid model of an Earth-like exoplanetary magnetospheric magnetic field, developed from a model of the Earth, we investigate the magnetospheric structure of planets located in the habitable zone around G-type stars. Different directions of the stellar wind magnetic field are considered and the corresponding variations in the magnetospheric structure are obtained. It is shown that the exoplanetary environment significantly depends on stellar wind magnetic field orientation and that the parameters of magnetospheric current systems depend on the distance to the stand-off magnetopause point.
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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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Forsyth C, Rae IJ, Murphy KR, Freeman MP, Huang C, Spence HE, Boyd AJ, Coxon JC, Jackman CM, Kalmoni NME, Watt CEJ. What effect do substorms have on the content of the radiation belts? JOURNAL OF GEOPHYSICAL RESEARCH. SPACE PHYSICS 2016; 121:6292-6306. [PMID: 27656336 PMCID: PMC5014235 DOI: 10.1002/2016ja022620] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Revised: 06/06/2016] [Accepted: 06/08/2016] [Indexed: 06/01/2023]
Abstract
Substorms are fundamental and dynamic processes in the magnetosphere, converting captured solar wind magnetic energy into plasma energy. These substorms have been suggested to be a key driver of energetic electron enhancements in the outer radiation belts. Substorms inject a keV "seed" population into the inner magnetosphere which is subsequently energized through wave-particle interactions up to relativistic energies; however, the extent to which substorms enhance the radiation belts, either directly or indirectly, has never before been quantified. In this study, we examine increases and decreases in the total radiation belt electron content (TRBEC) following substorms and geomagnetically quiet intervals. Our results show that the radiation belts are inherently lossy, shown by a negative median change in TRBEC at all intervals following substorms and quiet intervals. However, there are up to 3 times as many increases in TRBEC following substorm intervals. There is a lag of 1-3 days between the substorm or quiet intervals and their greatest effect on radiation belt content, shown in the difference between the occurrence of increases and losses in TRBEC following substorms and quiet intervals, the mean change in TRBEC following substorms or quiet intervals, and the cross correlation between SuperMAG AL (SML) and TRBEC. However, there is a statistically significant effect on the occurrence of increases and decreases in TRBEC up to a lag of 6 days. Increases in radiation belt content show a significant correlation with SML and SYM-H, but decreases in the radiation belt show no apparent link with magnetospheric activity levels.
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Affiliation(s)
- C. Forsyth
- Mullard Space Science LaboratoryUniversity College LondonDorkingUK
| | - I. J. Rae
- Mullard Space Science LaboratoryUniversity College LondonDorkingUK
| | - K. R. Murphy
- NASA Goddard Space Flight CenterGreenbeltMarylandUSA
| | | | - C.‐L. Huang
- Space Science CenterUniversity of New HampshireDurhamNew HampshireUSA
| | - H. E. Spence
- Space Science CenterUniversity of New HampshireDurhamNew HampshireUSA
| | - A. J. Boyd
- Space Science CenterUniversity of New HampshireDurhamNew HampshireUSA
- New Mexico ConsortiumLos AlamosNew MexicoUSA
| | - J. C. Coxon
- School of Physics and AstronomyUniversity of SouthamptonSouthamptonUK
| | - C. M. Jackman
- School of Physics and AstronomyUniversity of SouthamptonSouthamptonUK
| | - N. M. E. Kalmoni
- Mullard Space Science LaboratoryUniversity College LondonDorkingUK
| | - C. E. J. Watt
- Department of MeteorologyUniversity of ReadingReadingUK
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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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De Michelis P, Consolini G, Materassi M, Tozzi R. An information theory approach to the storm-substorm relationship. ACTA ACUST UNITED AC 2011. [DOI: 10.1029/2011ja016535] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- P. De Michelis
- Istituto Nazionale di Geofisica e Vulcanologia; Rome Italy
| | - G. Consolini
- Istituto Nazionale di Astrofisica-Istituto di Fisica dello Spazio Interplanetario; Rome Italy
| | - M. Materassi
- Istituto dei Sistemi Complessi; Consiglio Nazionale delle Ricerche; Sesto Fiorentino Italy
| | - R. Tozzi
- Istituto Nazionale di Geofisica e Vulcanologia; Rome Italy
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Affiliation(s)
- Kan Liou
- Johns Hopkins University Applied Physics Laboratory; Laurel Maryland USA
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Zou S, Moldwin MB, Lyons LR, Nishimura Y, Hirahara M, Sakanoi T, Asamura K, Nicolls MJ, Miyashita Y, Mende SB, Heinselman CJ. Identification of substorm onset location and preonset sequence using Reimei, THEMIS GBO, PFISR, and Geotail. ACTA ACUST UNITED AC 2010. [DOI: 10.1029/2010ja015520] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- S. Zou
- Department of Atmospheric, Oceanic and Space Sciences; University of Michigan; Ann Arbor Michigan USA
| | - M. B. Moldwin
- Department of Atmospheric, Oceanic and Space Sciences; University of Michigan; Ann Arbor Michigan USA
| | - L. R. Lyons
- Department of Atmospheric and Oceanic Sciences; University of California; Los Angeles California USA
| | - Y. Nishimura
- Department of Atmospheric and Oceanic Sciences; University of California; Los Angeles California USA
- Solar-Terrestrial Environment Laboratory; Nagoya University; Nagoya Japan
| | - M. Hirahara
- Department of Earth and Planetary Science; University of Tokyo; Tokyo Japan
| | - T. Sakanoi
- Planetary Plasma and Atmospheric Research Center; Tohoku University; Sendai Japan
| | - K. Asamura
- Institute of Space and Astronautical Science; Sagamihara Japan
| | - M. J. Nicolls
- Center for Geospace Studies; SRI International; Menlo Park California USA
| | - Y. Miyashita
- Solar-Terrestrial Environment Laboratory; Nagoya University; Nagoya Japan
| | - S. B. Mende
- Space Sciences Laboratory; University of California; Berkeley California USA
| | - C. J. Heinselman
- Center for Geospace Studies; SRI International; Menlo Park California USA
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Ieda A, Fairfield DH, Slavin JA, Liou K, Meng CI, Machida S, Miyashita Y, Mukai T, Saito Y, Nosé M, Shue JH, Parks GK, Fillingim MO. Longitudinal association between magnetotail reconnection and auroral breakup based on Geotail and Polar observations. ACTA ACUST UNITED AC 2008. [DOI: 10.1029/2008ja013127] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- A. Ieda
- Solar-Terrestrial Environment Laboratory; Nagoya University; Nagoya, Aichi Japan
| | - D. H. Fairfield
- Heliophysics Science Division; NASA Goddard Space Flight Center; Greenbelt Maryland USA
| | - J. A. Slavin
- Heliophysics Science Division; NASA Goddard Space Flight Center; Greenbelt Maryland USA
| | - K. Liou
- Applied Physics Laboratory; Johns Hopkins University; Laurel Maryland USA
| | - C.-I. Meng
- Applied Physics Laboratory; Johns Hopkins University; Laurel Maryland USA
| | - S. Machida
- Department of Geophysics; Kyoto University; Kyoto Japan
| | - Y. Miyashita
- Institute of Space and Astronautical Science; Japan Aerospace Exploration Agency; Sagamihara, Kanagawa Japan
| | - T. Mukai
- Institute of Space and Astronautical Science; Japan Aerospace Exploration Agency; Sagamihara, Kanagawa Japan
| | - Y. Saito
- Institute of Space and Astronautical Science; Japan Aerospace Exploration Agency; Sagamihara, Kanagawa Japan
| | - M. Nosé
- Data Analysis Center for Geomagnetism and Space Magnetism, Graduate School of Science; Kyoto University; Kyoto Japan
| | - J.-H. Shue
- Institute of Space Science; National Central University; Jhongli Taiwan
| | - G. K. Parks
- Space Sciences Laboratory; University of California; Berkeley California USA
| | - M. O. Fillingim
- Space Sciences Laboratory; University of California; Berkeley California USA
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Wilson GR, Ober DM, Germany GA, Lund EJ. Nightside auroral zone and polar cap ion outflow as a function of substorm size and phase. ACTA ACUST UNITED AC 2004. [DOI: 10.1029/2003ja009835] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- G. R. Wilson
- Mission Research Corporation; Nashua New Hampshire USA
| | - D. M. Ober
- Mission Research Corporation; Nashua New Hampshire USA
| | - G. A. Germany
- Center for Space Plasma and Aeronomic Research; University of Alabama in Huntsville; Huntsville Alabama USA
| | - E. J. Lund
- Space Science Center; University of New Hampshire; Durham New Hampshire USA
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11
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Uozumi T. Propagation characteristics of Pi 2 magnetic pulsations observed at ground high latitudes. ACTA ACUST UNITED AC 2004. [DOI: 10.1029/2003ja009898] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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12
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Meurant M. Propagation of electron and proton shock-induced aurora and the role of the interplanetary magnetic field and solar wind. ACTA ACUST UNITED AC 2004. [DOI: 10.1029/2004ja010453] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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Comparison of auroral processes: Earth and Jupiter. ACTA ACUST UNITED AC 2002. [DOI: 10.1029/130gm08] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Newell PT, Liou K, Sotirelis T, Meng CI. Auroral precipitation power during substorms: A Polar UV Imager-based superposed epoch analysis. ACTA ACUST UNITED AC 2001. [DOI: 10.1029/2000ja000428] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Liou K, Meng CI, Newell PT, Lui ATY, Reeves GD, Belian RD. Particle injections with auroral expansions. ACTA ACUST UNITED AC 2001. [DOI: 10.1029/2000ja003003] [Citation(s) in RCA: 27] [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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