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Zhang H, Zong Q, Connor H, Delamere P, Facskó G, Han D, Hasegawa H, Kallio E, Kis Á, Le G, Lembège B, Lin Y, Liu T, Oksavik K, Omidi N, Otto A, Ren J, Shi Q, Sibeck D, Yao S. Dayside Transient Phenomena and Their Impact on the Magnetosphere and Ionosphere. SPACE SCIENCE REVIEWS 2022; 218:40. [PMID: 35784192 PMCID: PMC9239986 DOI: 10.1007/s11214-021-00865-0] [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: 01/01/2021] [Accepted: 11/11/2021] [Indexed: 06/15/2023]
Abstract
Dayside transients, such as hot flow anomalies, foreshock bubbles, magnetosheath jets, flux transfer events, and surface waves, are frequently observed upstream from the bow shock, in the magnetosheath, and at the magnetopause. They play a significant role in the solar wind-magnetosphere-ionosphere coupling. Foreshock transient phenomena, associated with variations in the solar wind dynamic pressure, deform the magnetopause, and in turn generates field-aligned currents (FACs) connected to the auroral ionosphere. Solar wind dynamic pressure variations and transient phenomena at the dayside magnetopause drive magnetospheric ultra low frequency (ULF) waves, which can play an important role in the dynamics of Earth's radiation belts. These transient phenomena and their geoeffects have been investigated using coordinated in-situ spacecraft observations, spacecraft-borne imagers, ground-based observations, and numerical simulations. Cluster, THEMIS, Geotail, and MMS multi-mission observations allow us to track the motion and time evolution of transient phenomena at different spatial and temporal scales in detail, whereas ground-based experiments can observe the ionospheric projections of transient magnetopause phenomena such as waves on the magnetopause driven by hot flow anomalies or flux transfer events produced by bursty reconnection across their full longitudinal and latitudinal extent. Magnetohydrodynamics (MHD), hybrid, and particle-in-cell (PIC) simulations are powerful tools to simulate the dayside transient phenomena. This paper provides a comprehensive review of the present understanding of dayside transient phenomena at Earth and other planets, their geoeffects, and outstanding questions.
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Affiliation(s)
- Hui Zhang
- Physics Department & Geophysical Institute, University of Alaska Fairbanks, 2156 Koyukuk Drive, Fairbanks, AK 99775 USA
- Shandong University, Weihai, China
| | - Qiugang Zong
- Institute of Space Physics and Applied Technology, Peking University, Beijing, 100871 China
- Polar Research Institute of China, Shanghai, 200136 China
| | - Hyunju Connor
- Physics Department & Geophysical Institute, University of Alaska Fairbanks, 2156 Koyukuk Drive, Fairbanks, AK 99775 USA
- NASA Goddard Space Flight Center, Greenbelt, MD 20771 USA
| | - Peter Delamere
- Physics Department & Geophysical Institute, University of Alaska Fairbanks, 2156 Koyukuk Drive, Fairbanks, AK 99775 USA
| | - Gábor Facskó
- Department of Informatics, Milton Friedman University, 1039 Budapest, Hungary
- Wigner Research Centre for Physics, Konkoly-Thege Miklós út 29-33, 1121 Budapest, Hungary
| | | | - Hiroshi Hasegawa
- Institute of Space and Astronautical Science, JAXA, Sagamihara, Japan
| | | | - Árpád Kis
- Institute of Earth Physics and Space Science (ELKH EPSS), Sopron, Hungary
| | - Guan Le
- NASA Goddard Space Flight Center, Greenbelt, MD 20771 USA
| | - Bertrand Lembège
- LATMOS (Laboratoire Atmosphères, Milieux, Observations Spatiales), IPSL/CNRS/UVSQ, 11 Bd d’Alembert, Guyancourt, 78280 France
| | - Yu Lin
- Auburn University, Auburn, USA
| | - Terry Liu
- Physics Department & Geophysical Institute, University of Alaska Fairbanks, 2156 Koyukuk Drive, Fairbanks, AK 99775 USA
- Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, Los Angeles, USA
| | - Kjellmar Oksavik
- Birkeland Centre for Space Science, Department of Physics and Technology, University of Bergen, Bergen, Norway
- Arctic Geophysics, The University Centre in Svalbard, Longyearbyen, Norway
| | | | - Antonius Otto
- Physics Department & Geophysical Institute, University of Alaska Fairbanks, 2156 Koyukuk Drive, Fairbanks, AK 99775 USA
| | - Jie Ren
- Institute of Space Physics and Applied Technology, Peking University, Beijing, 100871 China
| | | | - David Sibeck
- NASA Goddard Space Flight Center, Greenbelt, MD 20771 USA
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2
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Woodfield EE, Glauert SA, Menietti JD, Averkamp TF, Horne RB, Shprits YY. Rapid Electron Acceleration in Low-Density Regions of Saturn's Radiation Belt by Whistler Mode Chorus Waves. GEOPHYSICAL RESEARCH LETTERS 2019; 46:7191-7198. [PMID: 31598019 PMCID: PMC6772095 DOI: 10.1029/2019gl083071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Revised: 05/30/2019] [Accepted: 06/17/2019] [Indexed: 06/10/2023]
Abstract
Electron acceleration at Saturn due to whistler mode chorus waves has previously been assumed to be ineffective; new data closer to the planet show it can be very rapid (factor of 104 flux increase at 1 MeV in 10 days compared to factor of 2). A full survey of chorus waves at Saturn is combined with an improved plasma density model to show that where the plasma frequency falls below the gyrofrequency additional strong resonances are observed favoring electron acceleration. This results in strong chorus acceleration between approximately 2.5 R S and 5.5 R S outside which adiabatic transport may dominate. Strong pitch angle dependence results in butterfly pitch angle distributions that flatten over a few days at 100s keV, tens of days at MeV energies which may explain observations of butterfly distributions of MeV electrons near L=3. Including cross terms in the simulations increases the tendency toward butterfly distributions.
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Affiliation(s)
| | | | - J. D. Menietti
- Department of Physics and AstronomyUniversity of IowaIowa CityIAUSA
| | - T. F. Averkamp
- Department of Physics and AstronomyUniversity of IowaIowa CityIAUSA
| | | | - Y. Y. Shprits
- Helmholtz Centre Potsdam, GFZ German Research Centre for GeosciencesPotsdamGermany
- Institute for Physics and AstronomyUniversität PotsdamPotsdamGermany
- Department of Earth, Planetary, and Space SciencesUniversity of CaliforniaLos AngelesCAUSA
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3
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Smith AW, Jackman CM, Thomsen MF. Magnetic reconnection in Saturn's magnetotail: A comprehensive magnetic field survey. JOURNAL OF GEOPHYSICAL RESEARCH. SPACE PHYSICS 2016; 121:2984-3005. [PMID: 27867795 PMCID: PMC5111619 DOI: 10.1002/2015ja022005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Revised: 02/01/2016] [Accepted: 03/03/2016] [Indexed: 05/04/2023]
Abstract
Reconnection within planetary magnetotails is responsible for locally energizing particles and changing the magnetic topology. Its role in terms of global magnetospheric dynamics can involve changing the mass and flux content of the magnetosphere. We have identified reconnection related events in spacecraft magnetometer data recorded during Cassini's exploration of Saturn's magnetotail. The events are identified from deflections in the north-south component of the magnetic field, significant above a background level. Data were selected to provide full tail coverage, encompassing the dawn and dusk flanks as well as the deepest midnight orbits. Overall 2094 reconnection related events were identified, with an average rate of 5.0 events per day. The majority of events occur in clusters (within 3 h of other events). We examine changes in this rate in terms of local time and latitude coverage, taking seasonal effects into account. The observed reconnection rate peaks postmidnight with more infrequent but steady loss seen on the dusk flank. We estimate the mass loss from the event catalog and find it to be insufficient to balance the input from the moon Enceladus. Several reasons for this discrepancy are discussed. The reconnection X line location appears to be highly variable, though a statistical separation between events tailward and planetward of the X line is observed at a radial distance of between 20 and 30RS downtail. The small sample size at dawn prevents comprehensive statistical comparison with the dusk flank observations in terms of flux closure.
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Affiliation(s)
- A. W. Smith
- Department of Physics and AstronomyUniversity of SouthamptonSouthamptonUK
| | - C. M. Jackman
- Department of Physics and AstronomyUniversity of SouthamptonSouthamptonUK
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4
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Dunn WR, Branduardi-Raymont G, Elsner RF, Vogt MF, Lamy L, Ford PG, Coates AJ, Gladstone GR, Jackman CM, Nichols JD, Rae IJ, Varsani A, Kimura T, Hansen KC, Jasinski JM. The impact of an ICME on the Jovian X-ray aurora. JOURNAL OF GEOPHYSICAL RESEARCH. SPACE PHYSICS 2016; 121:2274-2307. [PMID: 27867794 PMCID: PMC5111422 DOI: 10.1002/2015ja021888] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/07/2015] [Revised: 01/11/2016] [Accepted: 01/27/2016] [Indexed: 06/06/2023]
Abstract
We report the first Jupiter X-ray observations planned to coincide with an interplanetary coronal mass ejection (ICME). At the predicted ICME arrival time, we observed a factor of ∼8 enhancement in Jupiter's X-ray aurora. Within 1.5 h of this enhancement, intense bursts of non-Io decametric radio emission occurred. Spatial, spectral, and temporal characteristics also varied between ICME arrival and another X-ray observation two days later. Gladstone et al. (2002) discovered the polar X-ray hot spot and found it pulsed with 45 min quasiperiodicity. During the ICME arrival, the hot spot expanded and exhibited two periods: 26 min periodicity from sulfur ions and 12 min periodicity from a mixture of carbon/sulfur and oxygen ions. After the ICME, the dominant period became 42 min. By comparing Vogt et al. (2011) Jovian mapping models with spectral analysis, we found that during ICME arrival at least two distinct ion populations, from Jupiter's dayside, produced the X-ray aurora. Auroras mapping to magnetospheric field lines between 50 and 70 RJ were dominated by emission from precipitating sulfur ions (S7+,…,14+). Emissions mapping to closed field lines between 70 and 120 RJ and to open field lines were generated by a mixture of precipitating oxygen (O7+,8+) and sulfur/carbon ions, possibly implying some solar wind precipitation. We suggest that the best explanation for the X-ray hot spot is pulsed dayside reconnection perturbing magnetospheric downward currents, as proposed by Bunce et al. (2004). The auroral enhancement has different spectral, spatial, and temporal characteristics to the hot spot. By analyzing these characteristics and coincident radio emissions, we propose that the enhancement is driven directly by the ICME through Jovian magnetosphere compression and/or a large-scale dayside reconnection event.
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Affiliation(s)
- William R Dunn
- Mullard Space Science Laboratory, Department of Space and Climate Physics University College London Dorking UK; Centre for Planetary Science UCL/Birkbeck London UK
| | | | - Ronald F Elsner
- ZP12, NASA Marshall Space Flight Center Huntsville Alabama USA
| | - Marissa F Vogt
- Center for Space Physics Boston University Boston Massachusetts USA
| | - Laurent Lamy
- LESIA, Observatoire de Paris, CNRS, UPMC Université Paris Diderot Meudon France
| | - Peter G Ford
- Kavli Institute for Astrophysics and Space Research MIT Cambridge Massachusetts USA
| | - Andrew J Coates
- Mullard Space Science Laboratory, Department of Space and Climate Physics University College London Dorking UK; Centre for Planetary Science UCL/Birkbeck London UK
| | - G Randall Gladstone
- Space Science and Engineering Division Southwest Research Institute San Antonio Texas USA
| | - Caitriona M Jackman
- Department of Physics and Astronomy University of Southampton Southampton UK
| | - Jonathan D Nichols
- Department of Physics and Astronomy University of Leicester Leicester UK
| | - I Jonathan Rae
- Mullard Space Science Laboratory, Department of Space and Climate Physics University College London Dorking UK
| | - Ali Varsani
- Mullard Space Science Laboratory, Department of Space and Climate Physics University College London Dorking UK; Space Research Institute Austrian Academy of Sciences Graz Austria
| | - Tomoki Kimura
- Institute of Space and Astronautical Science Japan Aerospace Exploration Agency Sagamihara Japan; Nishina Center for Accelerator-Based Science RIKEN Wako Japan
| | - Kenneth C Hansen
- Department of Atmospheric, Oceanic and Space Sciences University of Michigan Ann Arbor Michigan USA
| | - Jamie M Jasinski
- Mullard Space Science Laboratory, Department of Space and Climate Physics University College London Dorking UK; Centre for Planetary Science UCL/Birkbeck London UK; Department of Atmospheric, Oceanic and Space Sciences University of Michigan Ann Arbor Michigan USA
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5
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Felici M, Arridge CS, Coates AJ, Badman SV, Dougherty MK, Jackman CM, Kurth WS, Melin H, Mitchell DG, Reisenfeld DB, Sergis N. Cassini observations of ionospheric plasma in Saturn's magnetotail lobes. JOURNAL OF GEOPHYSICAL RESEARCH. SPACE PHYSICS 2016; 121:338-357. [PMID: 27610291 PMCID: PMC4994772 DOI: 10.1002/2015ja021648] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Revised: 12/13/2015] [Accepted: 12/28/2015] [Indexed: 05/20/2023]
Abstract
Studies of Saturn's magnetosphere with the Cassini mission have established the importance of Enceladus as the dominant mass source for Saturn's magnetosphere. It is well known that the ionosphere is an important mass source at Earth during periods of intense geomagnetic activity, but lesser attention has been dedicated to study the ionospheric mass source at Saturn. In this paper we describe a case study of data from Saturn's magnetotail, when Cassini was located at ≃ 2200 h Saturn local time at 36 RS from Saturn. During several entries into the magnetotail lobe, tailward flowing cold electrons and a cold ion beam were observed directly adjacent to the plasma sheet and extending deeper into the lobe. The electrons and ions appear to be dispersed, dropping to lower energies with time. The composition of both the plasma sheet and lobe ions show very low fluxes (sometimes zero within measurement error) of water group ions. The magnetic field has a swept-forward configuration which is atypical for this region, and the total magnetic field strength is larger than expected at this distance from the planet. Ultraviolet auroral observations show a dawn brightening, and upstream heliospheric models suggest that the magnetosphere is being compressed by a region of high solar wind ram pressure. We interpret this event as the observation of ionospheric outflow in Saturn's magnetotail. We estimate a number flux between (2.95 ± 0.43) × 109 and (1.43 ± 0.21) × 1010 cm-2 s-1, 1 or about 2 orders of magnitude larger than suggested by steady state MHD models, with a mass source between 1.4 ×102 and 1.1 ×103 kg/s. After considering several configurations for the active atmospheric regions, we consider as most probable the main auroral oval, with associated mass source between 49.7 ±13.4 and 239.8 ±64.8 kg/s for an average auroral oval, and 10 ±4 and 49 ±23 kg/s for the specific auroral oval morphology found during this event. It is not clear how much of this mass is trapped within the magnetosphere and how much is lost to the solar wind.
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Affiliation(s)
- M. Felici
- Mullard Space Science LaboratoryUniversity College LondonDorkingUK
- Centre for Planetary Sciences at UCL/BirkbeckLondonUK
- Department of PhysicsLancaster UniversityLancasterUK
| | - C. S. Arridge
- Department of PhysicsLancaster UniversityLancasterUK
| | - A. J. Coates
- Mullard Space Science LaboratoryUniversity College LondonDorkingUK
- Centre for Planetary Sciences at UCL/BirkbeckLondonUK
| | - S. V. Badman
- Department of PhysicsLancaster UniversityLancasterUK
| | - M. K. Dougherty
- Space and Atmospheric Physics Group, The Blackett LaboratoryImperial College LondonLondonUK
| | - C. M. Jackman
- Department of Physics and AstronomyUniversity of SouthamptonSouthamptonUK
| | - W. S. Kurth
- Department of Physics and AstronomyUniversity of IowaIowa CityIowaUSA
| | - H. Melin
- Department of Physics and AstronomyUniversity of LeicesterLeicesterUK
| | - D. G. Mitchell
- The Johns Hopkins University Applied Physics LaboratoryLaurelMarylandUSA
| | - D. B. Reisenfeld
- Department of Physics and AstronomyUniversity of MontanaMissoulaMontanaUSA
| | - N. Sergis
- Mullard Space Science LaboratoryUniversity College LondonDorkingUK
- Office for Space ResearchAcademy of AthensAthensGreece
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Hadid LZ, Sahraoui F, Kiyani KH, Retinò A, Modolo R, Canu P, Masters A, Dougherty MK. NATURE OF THE MHD AND KINETIC SCALE TURBULENCE IN THE MAGNETOSHEATH OF SATURN:
CASSINI
OBSERVATIONS. ACTA ACUST UNITED AC 2015. [DOI: 10.1088/2041-8205/813/2/l29] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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7
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Pilkington NM, Achilleos N, Arridge CS, Guio P, Masters A, Ray LC, Sergis N, Thomsen MF, Coates AJ, Dougherty MK. Internally driven large-scale changes in the size of Saturn's magnetosphere. JOURNAL OF GEOPHYSICAL RESEARCH. SPACE PHYSICS 2015; 120:7289-7306. [PMID: 27867793 PMCID: PMC5111417 DOI: 10.1002/2015ja021290] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Revised: 07/22/2015] [Accepted: 07/26/2015] [Indexed: 05/20/2023]
Abstract
Saturn's magnetic field acts as an obstacle to solar wind flow, deflecting plasma around the planet and forming a cavity known as the magnetosphere. The magnetopause defines the boundary between the planetary and solar dominated regimes, and so is strongly influenced by the variable nature of pressure sources both outside and within. Following from Pilkington et al. (2014), crossings of the magnetopause are identified using 7 years of magnetic field and particle data from the Cassini spacecraft and providing unprecedented spatial coverage of the magnetopause boundary. These observations reveal a dynamical interaction where, in addition to the external influence of the solar wind dynamic pressure, internal drivers, and hot plasma dynamics in particular can take almost complete control of the system's dayside shape and size, essentially defying the solar wind conditions. The magnetopause can move by up to 10-15 planetary radii at constant solar wind dynamic pressure, corresponding to relatively "plasma-loaded" or "plasma-depleted" states, defined in terms of the internal suprathermal plasma pressure.
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Affiliation(s)
- N. M. Pilkington
- Atmospheric Physics Laboratory, Department of Physics and AstronomyUniversity College LondonLondonUK
- The Centre for Planetary SciencesUCL/BirkbeckLondonUK
| | - N. Achilleos
- Atmospheric Physics Laboratory, Department of Physics and AstronomyUniversity College LondonLondonUK
- The Centre for Planetary SciencesUCL/BirkbeckLondonUK
| | | | - P. Guio
- Atmospheric Physics Laboratory, Department of Physics and AstronomyUniversity College LondonLondonUK
- The Centre for Planetary SciencesUCL/BirkbeckLondonUK
| | - A. Masters
- Blackett LaboratoryImperial College LondonLondonUK
| | - L. C. Ray
- Atmospheric Physics Laboratory, Department of Physics and AstronomyUniversity College LondonLondonUK
- The Centre for Planetary SciencesUCL/BirkbeckLondonUK
| | - N. Sergis
- Academy of AthensOffice of Space Research and TechnologyAthensGreece
| | | | - A. J. Coates
- The Centre for Planetary SciencesUCL/BirkbeckLondonUK
- Mullard Space Science Laboratory, Department of Space and Climate PhysicsUniversity College LondonDorkingUK
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8
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Coates AJ, Wellbrock A, Waite JH, Jones GH. A new upper limit to the field-aligned potential near Titan. GEOPHYSICAL RESEARCH LETTERS 2015; 42:4676-4684. [PMID: 27609997 PMCID: PMC4994318 DOI: 10.1002/2015gl064474] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Accepted: 05/22/2015] [Indexed: 06/06/2023]
Abstract
Neutral particles dominate regions of the Saturn magnetosphere and locations near several of Saturn's moons. Sunlight ionizes neutrals, producing photoelectrons with characteristic energy spectra. The Cassini plasma spectrometer electron spectrometer has detected photoelectrons throughout these regions, where photoelectrons may be used as tracers of magnetic field morphology. They also enhance plasma escape by setting up an ambipolar electric field, since the relatively energetic electrons move easily along the magnetic field. A similar mechanism is seen in the Earth's polar wind and at Mars and Venus. Here we present a new analysis of Titan photoelectron data, comparing spectra measured in the sunlit ionosphere at ~1.4 Titan radii (RT) and at up to 6.8 RT away. This results in an upper limit on the potential of 2.95 V along magnetic field lines associated with Titan at up to 6.8 RT, which is comparable to some similar estimates for photoelectrons seen in Earth's magnetosphere.
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Affiliation(s)
- Andrew J Coates
- Mullard Space Science Laboratory University College London London UK; Centre for Planetary Sciences at UCL/Birkbeck London UK
| | - Anne Wellbrock
- Mullard Space Science Laboratory University College London London UK; Centre for Planetary Sciences at UCL/Birkbeck London UK
| | | | - Geraint H Jones
- Mullard Space Science Laboratory University College London London UK; Centre for Planetary Sciences at UCL/Birkbeck London UK
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9
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Mitchell CJ, Porco CC, Weiss JW. TRACKING THE GEYSERS OF ENCELADUS INTO SATURN’S E RING. ACTA ACUST UNITED AC 2015. [DOI: 10.1088/0004-6256/149/5/156] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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10
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Mauk BH. Comparative investigation of the energetic ion spectra comprising the magnetospheric ring currents of the solar system. JOURNAL OF GEOPHYSICAL RESEARCH. SPACE PHYSICS 2014; 119:9729-9746. [PMID: 26167438 PMCID: PMC4497457 DOI: 10.1002/2014ja020392] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Accepted: 11/08/2014] [Indexed: 05/29/2023]
Abstract
Investigated here are factors that control the intensities and shapes of energetic ion spectra that make up the ring current populations of the strongly magnetized planets of the solar system, specifically those of Earth, Jupiter, Saturn, Uranus, and Neptune. Following a previous and similar comparative investigation of radiation belt electrons, we here turn our attention to ions. Specifically, we examine the possible role of the differential ion Kennel-Petschek limit, as moderated by Electromagnetic Ion Cyclotron (EMIC) waves, as a standard for comparing the most intense ion spectra within the strongly magnetized planetary magnetospheres. In carrying out this investigation, the substantial complexities engendered by the very different ion composition distributions of these diverse magnetospheres must be addressed, given that the dispersion properties of the EMIC waves are strongly determined by the ion composition of the plasmas within which the waves propagate. Chosen for comparison are the ion spectra within these systems that are the most intense observed, specifically at 100 keV and 1 MeV. We find that Earth and Jupiter are unique in having their most intense ion spectra likely limited and sculpted by the Kennel-Petschek process. The ion spectra of Saturn, Uranus, and Neptune reside far below their respective limits and are likely limited by interactions with gas and dust (Saturn) and by the absence of robust ion acceleration processes (Uranus and Neptune). Suggestions are provided for further testing the efficacy of the differential Kennel-Petschek limit for ions using the Van Allen Probes.
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Affiliation(s)
- B H Mauk
- Johns Hopkins University Applied Physics LaboratoryLaurel, Maryland, USA
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11
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Teolis BD, Sillanpää I, Waite JH, Khurana KK. Surface current balance and thermoelectric whistler wings at airless astrophysical bodies: Cassini at Rhea. JOURNAL OF GEOPHYSICAL RESEARCH. SPACE PHYSICS 2014; 119:8881-8901. [PMID: 26167436 PMCID: PMC4497460 DOI: 10.1002/2014ja020094] [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: 04/18/2014] [Revised: 10/02/2014] [Accepted: 10/04/2014] [Indexed: 06/04/2023]
Abstract
UNLABELLED Sharp magnetic perturbations found by the Cassini spacecraft at the edge of the Rhea flux tube are consistent with field-aligned flux tube currents. The current system results from the difference of ion and electron gyroradii and the requirement to balance currents on the sharp Rhea surface. Differential-type hybrid codes that solve for ion velocity and magnetic field have an intrinsic difficulty modeling the plasma absorber's sharp surface. We overcome this problem by instead using integral equations to solve for ion and electron currents and obtain agreement with the magnetic perturbations at Rhea's flux tube edge. An analysis of the plasma dispersion relations and Cassini data reveals that field-guided whistler waves initiated by (1) the electron velocity anisotropy in the flux tube and (2) interaction with surface sheath electrostatic waves on topographic scales may facilitate propagation of the current system to large distances from Rhea. Current systems like those at Rhea should occur generally, for plasma absorbers of any size such as spacecraft or planetary bodies, in a wide range of space plasma environments. Motion through the plasma is not essential since the current system is thermodynamic in origin, excited by heat flow into the object. The requirements are a difference of ion and electron gyroradii and a sharp surface, i.e., without a significant thick atmosphere. KEY POINTS Surface current balance condition yields a current system at astronomical bodiesCurrent system possible for sharp (airless) objects of any sizeCurrent system is thermoelectric and motion through the plasma nonessential.
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Affiliation(s)
- B D Teolis
- Space Science Division, Southwest Research Institute San Antonio, Texas, USA
| | - I Sillanpää
- Space Science Division, Southwest Research Institute San Antonio, Texas, USA
| | - J H Waite
- Space Science Division, Southwest Research Institute San Antonio, Texas, USA
| | - K K Khurana
- Institute of Geophysics and Planetary Physics, University of California Los Angeles, California, USA
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12
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Nichols JD, Badman SV, Baines KH, Brown RH, Bunce EJ, Clarke JT, Cowley SWH, Crary FJ, Dougherty MK, Gérard JC, Grocott A, Grodent D, Kurth WS, Melin H, Mitchell DG, Pryor WR, Stallard TS. Dynamic auroral storms on Saturn as observed by the Hubble Space Telescope. GEOPHYSICAL RESEARCH LETTERS 2014; 41:3323-3330. [PMID: 26074636 PMCID: PMC4459195 DOI: 10.1002/2014gl060186] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Accepted: 04/28/2014] [Indexed: 05/29/2023]
Abstract
We present observations of significant dynamics within two UV auroral storms observed on Saturn using the Hubble Space Telescope in April/May 2013. Specifically, we discuss bursts of auroral emission observed at the poleward boundary of a solar wind-induced auroral storm, propagating at ∼330% rigid corotation from near ∼01 h LT toward ∼08 h LT. We suggest that these are indicative of ongoing, bursty reconnection of lobe flux in the magnetotail, providing strong evidence that Saturn's auroral storms are caused by large-scale flux closure. We also discuss the later evolution of a similar storm and show that the emission maps to the trailing region of an energetic neutral atom enhancement. We thus identify the auroral form with the upward field-aligned continuity currents flowing into the associated partial ring current.
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Affiliation(s)
- J D Nichols
- Department of Physics and Astronomy, University of Leicester Leicester, UK
| | - S V Badman
- Department of Physics and Astronomy, University of Leicester Leicester, UK ; Department of Physics, Lancaster University Lancaster, UK
| | - K H Baines
- Space Science and Engineering Center, University of Wisconsin-Madison Madison, Wisconsin, USA
| | - R H Brown
- Lunar and Planetary Lab, University of Arizona Tucson, Arizona, USA
| | - E J Bunce
- Department of Physics and Astronomy, University of Leicester Leicester, UK
| | - J T Clarke
- Center for Space Physics, Boston University Boston, Massachusetts, USA
| | - S W H Cowley
- Department of Physics and Astronomy, University of Leicester Leicester, UK
| | - F J Crary
- Laboratory for Atmospheric and Space Physics, University of Colorado Boulder Boulder, Colorado, USA
| | - M K Dougherty
- Blackett Laboratory, Imperial College London London, UK
| | - J-C Gérard
- Laboratoire de Physique Atmospherique et Planetaire, Universite de Liege Liege, Belgium
| | - A Grocott
- Department of Physics and Astronomy, University of Leicester Leicester, UK ; Department of Physics, Lancaster University Lancaster, UK
| | - D Grodent
- Laboratoire de Physique Atmospherique et Planetaire, Universite de Liege Liege, Belgium
| | - W S Kurth
- Department of Physics and Astronomy, University of Iowa Iowa City, Iowa, USA
| | - H Melin
- Department of Physics and Astronomy, University of Leicester Leicester, UK
| | - D G Mitchell
- Applied Physics Laboratory, Johns Hopkins University Laurel, Maryland, USA
| | - W R Pryor
- Department of Science, Central Arizona College Coolidge, Arizona, USA
| | - T S Stallard
- Department of Physics and Astronomy, University of Leicester Leicester, UK
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13
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Jia X, Kivelson MG. Driving Saturn's magnetospheric periodicities from the upper atmosphere/ionosphere: Magnetotail response to dual sources. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/2012ja018183] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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14
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Garnier P, Wahlund JE, Holmberg MKG, Morooka M, Grimald S, Eriksson A, Schippers P, Gurnett DA, Krimigis SM, Krupp N, Coates A, Crary F, Gustafsson G. The detection of energetic electrons with the Cassini Langmuir probe at Saturn. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/2011ja017298] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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15
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Szego K, Nemeth Z, Erdos G, Foldy L, Bebesi Z, Thomsen M, Delapp D. Location of the magnetodisk in the nightside outer magnetosphere of Saturn near equinox based on ion densities. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/2012ja017817] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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16
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Thomsen MF, Roussos E, Andriopoulou M, Kollmann P, Arridge CS, Paranicas CP, Gurnett DA, Powell RL, Tokar RL, Young DT. Saturn's inner magnetospheric convection pattern: Further evidence. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/2011ja017482] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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17
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Liu X, Hill TW. Effects of finite plasma pressure on centrifugally driven convection in Saturn's inner magnetosphere. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/2012ja017827] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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18
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Ray LC, Galand M, Moore LE, Fleshman B. Characterizing the limitations to the coupling between Saturn's ionosphere and middle magnetosphere. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/2012ja017735] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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19
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Hill TW, Thomsen MF, Tokar RL, Coates AJ, Lewis GR, Young DT, Crary FJ, Baragiola RA, Johnson RE, Dong Y, Wilson RJ, Jones GH, Wahlund JE, Mitchell DG, Horányi M. Charged nanograins in the Enceladus plume. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/2011ja017218] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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20
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Schippers P, André N, Gurnett DA, Lewis GR, Persoon AM, Coates AJ. Identification of electron field-aligned current systems in Saturn's magnetosphere. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/2011ja017352] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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21
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Jia X, Kivelson MG, Gombosi TI. Driving Saturn's magnetospheric periodicities from the upper atmosphere/ionosphere. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/2011ja017367] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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22
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Wilson RJ, Delamere PA, Bagenal F, Masters A. Kelvin-Helmholtz instability at Saturn's magnetopause: Cassini ion data analysis. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/2011ja016723] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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23
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Arridge CS, André N, Khurana KK, Russell CT, Cowley SWH, Provan G, Andrews DJ, Jackman CM, Coates AJ, Sittler EC, Dougherty MK, Young DT. Periodic motion of Saturn's nightside plasma sheet. ACTA ACUST UNITED AC 2011. [DOI: 10.1029/2011ja016827] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- C. S. Arridge
- Mullard Space Science Laboratory; University College London; Dorking UK
- Centre for Planetary Sciences at UCL/Birkbeck; London UK
| | - N. André
- Institut de Recherche en Astrophysique et Planétologie; CNRS; Toulouse France
- Institut de Recherche en Astrophysique et Planétologie; Université de Toulouse, UPS-OMP; Toulouse France
| | - K. K. Khurana
- Institute for Geophysics and Planetary Physics; University of California; Los Angeles California USA
| | - C. T. Russell
- Institute for Geophysics and Planetary Physics; University of California; Los Angeles California USA
| | - S. W. H. Cowley
- Department of Physics and Astronomy; University of Leicester; Leicester UK
| | - G. Provan
- Department of Physics and Astronomy; University of Leicester; Leicester UK
| | - D. J. Andrews
- Department of Physics and Astronomy; University of Leicester; Leicester UK
| | - C. M. Jackman
- Centre for Planetary Sciences at UCL/Birkbeck; London UK
- Blackett Laboratory; Imperial College London; London UK
- Department of Physics and Astronomy; University College London; London UK
| | - A. J. Coates
- Mullard Space Science Laboratory; University College London; Dorking UK
- Centre for Planetary Sciences at UCL/Birkbeck; London UK
| | - E. C. Sittler
- NASA Goddard Space Flight Center; Greenbelt Maryland USA
| | | | - D. T. Young
- Southwest Research Institute; San Antonio Texas USA
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24
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Delamere PA, Wilson RJ, Masters A. Kelvin-Helmholtz instability at Saturn's magnetopause: Hybrid simulations. ACTA ACUST UNITED AC 2011. [DOI: 10.1029/2011ja016724] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- P. A. Delamere
- Laboratory for Atmospheric and Space Physics; University of Colorado; Boulder Colorado USA
| | - R. J. Wilson
- Laboratory for Atmospheric and Space Physics; University of Colorado; Boulder Colorado USA
| | - A. Masters
- Mullard Space Science Laboratory, Department of Space and Climate Physics; University College London; Holmbury St. Mary UK
- Centre for Planetary Sciences at UCL/Birkbeck; London UK
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25
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Szego K, Nemeth Z, Erdos G, Foldy L, Thomsen M, Delapp D. The plasma environment of Titan: The magnetodisk of Saturn near the encounters as derived from ion densities measured by the Cassini/CAPS plasma spectrometer. ACTA ACUST UNITED AC 2011. [DOI: 10.1029/2011ja016629] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- K. Szego
- KFKI Research Institute for Particle and Nuclear Physics; Budapest Hungary
| | - Z. Nemeth
- KFKI Research Institute for Particle and Nuclear Physics; Budapest Hungary
| | - G. Erdos
- KFKI Research Institute for Particle and Nuclear Physics; Budapest Hungary
| | - L. Foldy
- KFKI Research Institute for Particle and Nuclear Physics; Budapest Hungary
| | - M. Thomsen
- Los Alamos National Laboratory; Los Alamos New Mexico USA
| | - D. Delapp
- Los Alamos National Laboratory; Los Alamos New Mexico USA
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26
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Németh Z, Szego K, Bebesi Z, Erdős G, Foldy L, Rymer A, Sittler EC, Coates AJ, Wellbrock A. Ion distributions of different Kronian plasma regions. ACTA ACUST UNITED AC 2011. [DOI: 10.1029/2011ja016585] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Zoltán Németh
- Department of Space Physics; KFKI Research Institute for Particle and Nuclear Physics; Budapest Hungary
| | - Karoly Szego
- Department of Space Physics; KFKI Research Institute for Particle and Nuclear Physics; Budapest Hungary
| | - Zsófia Bebesi
- Max Planck Institute for Solar System Research; Katlenburg-Lindau Germany
| | - Géza Erdős
- Department of Space Physics; KFKI Research Institute for Particle and Nuclear Physics; Budapest Hungary
| | - Lajos Foldy
- Department of Space Physics; KFKI Research Institute for Particle and Nuclear Physics; Budapest Hungary
| | - Abigail Rymer
- Johns Hopkins University Applied Physics Laboratory; Laurel MD USA
| | | | - Andrew J. Coates
- Planetary Group, Mullard Space Science Laboratories; University College London; Dorking UK
| | - Anne Wellbrock
- Planetary Group, Mullard Space Science Laboratories; University College London; Dorking UK
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27
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Sillanpää I, Young DT, Crary F, Thomsen M, Reisenfeld D, Wahlund JE, Bertucci C, Kallio E, Jarvinen R, Janhunen P. Cassini Plasma Spectrometer and hybrid model study on Titan's interaction: Effect of oxygen ions. ACTA ACUST UNITED AC 2011. [DOI: 10.1029/2011ja016443] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- I. Sillanpää
- Space Science and Engineering Division; Southwest Research Institute; San Antonio Texas USA
| | - D. T. Young
- Space Science and Engineering Division; Southwest Research Institute; San Antonio Texas USA
| | - F. Crary
- Space Science and Engineering Division; Southwest Research Institute; San Antonio Texas USA
| | - M. Thomsen
- Los Alamos National Laboratory; Los Alamos New Mexico USA
| | - D. Reisenfeld
- Department of Physics and Astronomy; University of Montana; Missoula Montana USA
| | | | - C. Bertucci
- Institute for Astronomy and Space Physics; Buenos Aires Argentina
| | - E. Kallio
- Finnish Meteorological Institute; Helsinki Finland
| | - R. Jarvinen
- Finnish Meteorological Institute; Helsinki Finland
| | - P. Janhunen
- Finnish Meteorological Institute; Helsinki Finland
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28
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Kellett S, Arridge CS, Bunce EJ, Coates AJ, Cowley SWH, Dougherty MK, Persoon AM, Sergis N, Wilson RJ. Saturn's ring current: Local time dependence and temporal variability. ACTA ACUST UNITED AC 2011. [DOI: 10.1029/2010ja016216] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- S. Kellett
- Department of Physics and Astronomy; University of Leicester; Leicester UK
| | - C. S. Arridge
- Mullard Space Science Laboratory; University College London; Dorking UK
| | - E. J. Bunce
- Department of Physics and Astronomy; University of Leicester; Leicester UK
| | - A. J. Coates
- Mullard Space Science Laboratory; University College London; Dorking UK
| | - S. W. H. Cowley
- Department of Physics and Astronomy; University of Leicester; Leicester UK
| | - M. K. Dougherty
- Space and Atmospheric Physics Group; Imperial College London; London UK
| | - A. M. Persoon
- Department of Physics and Astronomy; University of Iowa; Iowa City Iowa USA
| | - N. Sergis
- Office for Space Research and Technology; Academy of Athens; Athens Greece
| | - R. J. Wilson
- Laboratory for Atmospheric and Space Physics; University of Colorado at Boulder; Boulder Colorado USA
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29
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Bagenal F, Delamere PA. Flow of mass and energy in the magnetospheres of Jupiter and Saturn. ACTA ACUST UNITED AC 2011. [DOI: 10.1029/2010ja016294] [Citation(s) in RCA: 222] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Fran Bagenal
- Laboratory for Atmospheric and Space Physics; University of Colorado at Boulder; Boulder Colorado USA
| | - Peter A. Delamere
- Laboratory for Atmospheric and Space Physics; University of Colorado at Boulder; Boulder Colorado USA
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