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Zou Y, Walsh BM, Chen L, Ng J, Shi X, Wang C, Lyons LR, Liu J, Angelopoulos V, McWilliams KA, Michael Ruohoniemi J. Unsteady Magnetopause Reconnection Under Quasi-Steady Solar Wind Driving. GEOPHYSICAL RESEARCH LETTERS 2022; 49:e2021GL096583. [PMID: 35865078 PMCID: PMC9285935 DOI: 10.1029/2021gl096583] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Revised: 12/16/2021] [Accepted: 12/20/2021] [Indexed: 06/15/2023]
Abstract
The intrinsic temporal nature of magnetic reconnection at the magnetopause has been an active area of research. Both temporally steady and intermittent reconnection have been reported. We examine the steadiness of reconnection using space-ground conjunctions under quasi-steady solar wind driving. The spacecraft suggests that reconnection is first inactive, and then activates. The radar further suggests that after activation, reconnection proceeds continuously but unsteadily. The reconnection electric field shows variations at frequencies below 10 mHz with peaks at 3 and 5 mHz. The variation amplitudes are ∼10-30 mV/m in the ionosphere, and 0.3-0.8 mV/m at the equatorial magnetopause. Such amplitudes represent 30%-60% of the peak reconnection electric field. The unsteadiness of reconnection can be plausibly explained by the fluctuating magnetic field in the turbulent magnetosheath. A comparison with a previous global hybrid simulation suggests that it is the foreshock waves that drive the magnetosheath fluctuations, and hence modulate the reconnection.
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Affiliation(s)
- Ying Zou
- Department of Space ScienceUniversity of Alabama in HuntsvilleHuntsvilleALUSA
| | - Brian M. Walsh
- Department of Mechanical Engineering and Center for Space PhysicsBoston UniversityBostonMAUSA
| | - Li‐Jen Chen
- NASA Goddard Space Flight CenterGreenbeltMDUSA
| | - Jonathan Ng
- NASA Goddard Space Flight CenterGreenbeltMDUSA
- Department of AstronomyUniversity of MarylandCollege ParkMDUSA
| | - Xueling Shi
- The Bradley Department of Electrical and Computer EngineeringVirginia TechBlacksburgVAUSA
- High Altitude ObservatoryNational Center for Atmospheric ResearchBoulderCOUSA
| | - Chih‐Ping Wang
- Department of Atmospheric and Oceanic SciencesUniversity of CaliforniaLos AngelesCAUSA
| | - Larry R. Lyons
- Department of Atmospheric and Oceanic SciencesUniversity of CaliforniaLos AngelesCAUSA
| | - Jiang Liu
- Department of Atmospheric and Oceanic SciencesUniversity of CaliforniaLos AngelesCAUSA
- Department of Earth, Planetary and Space SciencesUniversity of CaliforniaLos AngelesCAUSA
| | - Vassilis Angelopoulos
- Department of Earth, Planetary and Space SciencesUniversity of CaliforniaLos AngelesCAUSA
| | - Kathryn A. McWilliams
- Department of Physics & Engineering PhysicsUniversity of SaskatchewanSaskatoonSKCanada
| | - J. Michael Ruohoniemi
- The Bradley Department of Electrical and Computer EngineeringVirginia TechBlacksburgVAUSA
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Trattner KJ, Petrinec SM, Fuselier SA. The Location of Magnetic Reconnection at Earth's Magnetopause. SPACE SCIENCE REVIEWS 2021; 217:41. [PMID: 34720216 PMCID: PMC8550343 DOI: 10.1007/s11214-021-00817-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Accepted: 03/08/2021] [Indexed: 06/13/2023]
Abstract
One of the major questions about magnetic reconnection is how specific solar wind and interplanetary magnetic field conditions influence where reconnection occurs at the Earth's magnetopause. There are two reconnection scenarios discussed in the literature: a) anti-parallel reconnection and b) component reconnection. Early spacecraft observations were limited to the detection of accelerated ion beams in the magnetopause boundary layer to determine the general direction of the reconnection X-line location with respect to the spacecraft. An improved view of the reconnection location at the magnetopause evolved from ionospheric emissions observed by polar-orbiting imagers. These observations and the observations of accelerated ion beams revealed that both scenarios occur at the magnetopause. Improved methodology using the time-of-flight effect of precipitating ions in the cusp regions and the cutoff velocity of the precipitating and mirroring ion populations was used to pinpoint magnetopause reconnection locations for a wide range of solar wind conditions. The results from these methodologies have been used to construct an empirical reconnection X-line model known as the Maximum Magnetic Shear model. Since this model's inception, several tests have confirmed its validity and have resulted in modifications to the model for certain solar wind conditions. This review article summarizes the observational evidence for the location of magnetic reconnection at the Earth's magnetopause, emphasizing the properties and efficacy of the Maximum Magnetic Shear Model.
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Affiliation(s)
| | | | - S. A. Fuselier
- Southwest Research Institute, San Antonio, TX USA
- University of Texas at San Antonio, San Antonio, TX USA
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Trattner KJ, Onsager TG, Petrinec SM, Fuselier SA. Distinguishing between pulsed and continuous reconnection at the dayside magnetopause. JOURNAL OF GEOPHYSICAL RESEARCH. SPACE PHYSICS 2015; 120:1684-1696. [PMID: 27656333 PMCID: PMC5014232 DOI: 10.1002/2014ja020713] [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: 10/09/2014] [Revised: 01/22/2015] [Accepted: 01/25/2015] [Indexed: 06/06/2023]
Abstract
Magnetic reconnection has been established as the dominant mechanism by which magnetic fields in different regions change topology to create open magnetic field lines that allow energy and momentum to flow into the magnetosphere. One of the persistent problems of magnetic reconnection is the question of whether the process is continuous or intermittent and what input condition(s) might favor one type of reconnection over the other. Observations from imagers that record FUV emissions caused by precipitating cusp ions demonstrate the global nature of magnetic reconnection. Those images show continuous ionospheric emissions even during changing interplanetary magnetic field conditions. On the other hand, in situ observations from polar-orbiting satellites show distinctive cusp structures in flux distributions of precipitating ions, which are interpreted as the telltale signature of intermittent reconnection. This study uses a modification of the low-velocity cutoff method, which was previously successfully used to determine the location of the reconnection site, to calculate for the cusp ion distributions the "time since reconnection occurred." The "time since reconnection" is used to determine the "reconnection time" for the cusp magnetic field lines where these distributions have been observed. The profile of the reconnection time, either continuous or stepped, is a direct measurement of the nature of magnetic reconnection at the reconnection site. This paper will discuss a continuous and pulsed reconnection event from the Polar spacecraft to illustrate the methodology.
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Affiliation(s)
| | | | | | - S. A. Fuselier
- Southwest Research InstituteSan AntonioTexasUSA
- Department of Physics and AstronomyUniversity of Texas at San AntonioSan AntonioTexasUSA
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Jasinski JM, Arridge CS, Lamy L, Leisner JS, Thomsen MF, Mitchell DG, Coates AJ, Radioti A, Jones GH, Roussos E, Krupp N, Grodent D, Dougherty MK, Waite JH. Cusp observation at Saturn's high-latitude magnetosphere by the Cassini spacecraft. GEOPHYSICAL RESEARCH LETTERS 2014; 41:1382-1388. [PMID: 25821276 PMCID: PMC4373149 DOI: 10.1002/2014gl059319] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2014] [Accepted: 02/13/2014] [Indexed: 05/24/2023]
Abstract
UNLABELLED We report on the first analysis of magnetospheric cusp observations at Saturn by multiple in situ instruments onboard the Cassini spacecraft. Using this we infer the process of reconnection was occurring at Saturn's magnetopause. This agrees with remote observations that showed the associated auroral signatures of reconnection. Cassini crossed the northern cusp around noon local time along a poleward trajectory. The spacecraft observed ion energy-latitude dispersions-a characteristic signature of the terrestrial cusp. This ion dispersion is "stepped," which shows that the reconnection is pulsed. The ion energy-pitch angle dispersions suggest that the field-aligned distance from the cusp to the reconnection site varies between ∼27 and 51 RS . An intensification of lower frequencies of the Saturn kilometric radiation emissions suggests the prior arrival of a solar wind shock front, compressing the magnetosphere and providing more favorable conditions for magnetopause reconnection. KEY POINTS We observe evidence for reconnection in the cusp plasma at SaturnWe present evidence that the reconnection process can be pulsed at SaturnSaturn's cusp shows similar characteristics to the terrestrial cusp.
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Affiliation(s)
- J M Jasinski
- Mullard Space Science Laboratory, Department of Space and Climate Physics, University College London Dorking, Surrey, UK ; Centre for Planetary Sciences, UCL/Birkbeck London, UK
| | - C S Arridge
- Mullard Space Science Laboratory, Department of Space and Climate Physics, University College London Dorking, Surrey, UK ; Centre for Planetary Sciences, UCL/Birkbeck London, UK
| | - L Lamy
- LESIA, Observatoire de Paris, CNRS, UPMC, Université Paris 6, Université Paris Diderot Meudon, France
| | - J S Leisner
- Blackett Laboratory, Department of Physics, Imperial College London London, UK
| | - M F Thomsen
- Planetary Science Institute Tucson, Arizona, USA
| | - D G Mitchell
- Applied Physics Laboratory, Johns Hopkins University Laurel, Maryland, USA
| | - A J Coates
- Mullard Space Science Laboratory, Department of Space and Climate Physics, University College London Dorking, Surrey, UK ; Centre for Planetary Sciences, UCL/Birkbeck London, UK
| | - A Radioti
- Laboratoire de Physique Atmosphérique et Planétaire, Institut d'Astrophysique et de Géophysique, Université de Liége Liege, Belgium
| | - G H Jones
- Mullard Space Science Laboratory, Department of Space and Climate Physics, University College London Dorking, Surrey, UK ; Centre for Planetary Sciences, UCL/Birkbeck London, UK
| | - E Roussos
- Max-Planck-Institut für Sonnensystemforschung Göttingen, Germany
| | - N Krupp
- Max-Planck-Institut für Sonnensystemforschung Göttingen, Germany
| | - D Grodent
- Laboratoire de Physique Atmosphérique et Planétaire, Institut d'Astrophysique et de Géophysique, Université de Liége Liege, Belgium
| | | | - J H Waite
- Southwest Research Institute, Space Science and Engineering Division San Antonio, Texas, USA
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Dunlop MW, Zhang QH, Bogdanova YV, Lockwood M, Pu Z, Hasegawa H, Wang J, Taylor MGGT, Berchem J, Lavraud B, Eastwood J, Volwerk M, Shen C, Shi JK, Constantinescu D, Frey H, Fazakerley AN, Sibeck D, Escoubet P, Wild JA, Liu ZX. Extended magnetic reconnection across the dayside magnetopause. PHYSICAL REVIEW LETTERS 2011; 107:025004. [PMID: 21797615 DOI: 10.1103/physrevlett.107.025004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2010] [Indexed: 05/31/2023]
Abstract
The extent of where magnetic reconnection (MR), the dominant process responsible for energy and plasma transport into the magnetosphere, operates across Earth's dayside magnetopause has previously been only indirectly shown by observations. We report the first direct evidence of X-line structure resulting from the operation of MR at each of two widely separated locations along the tilted, subsolar line of maximum current on Earth's magnetopause, confirming the operation of MR at two or more sites across the extended region where MR is expected to occur. The evidence results from in-situ observations of the associated ion and electron plasma distributions, present within each magnetic X-line structure, taken by two spacecraft passing through the active MR regions simultaneously.
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Affiliation(s)
- M W Dunlop
- Rutherford-Appleton Laboratory, Chilton, Oxfordshire, OX11 0QX, United Kingdom.
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Cai H, Ma S, Dunlop MW, Bogdanova Y, Davies JA, Pitout F. Cluster observations of high-altitude cusp during multiple fast-turning IMF. CHINESE SCIENCE BULLETIN-CHINESE 2010. [DOI: 10.1007/s11434-009-0306-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Strangeway RJ, Russell CT, Carlson CW, McFadden JP, Ergun RE, Temerin M, Klumpar DM, Peterson WK, Moore TE. Cusp field-aligned currents and ion outflows. ACTA ACUST UNITED AC 2000. [DOI: 10.1029/2000ja900032] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Kan JR, Deehr CS, Lyu LH, Newell PT. Ionospheric signatures of patchy-intermittent reconnection at dayside magnetopause. ACTA ACUST UNITED AC 1996. [DOI: 10.1029/96ja00462] [Citation(s) in RCA: 12] [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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