Magnetospheric physics

  • Article
    | Open Access

    Superbolts are powerful, rare lightning events. Here, the authors show simultaneous satellite and ground measurements of a superbolt, and demonstrate different properties of superbolts and lightnings.

    • J.-F. Ripoll
    • , T. Farges
    •  & S. Pédeboy
  • Article
    | Open Access

    During geomagnetic substorms, the energy accumulated from solar wind is abruptly transported to ionosphere. Here, the authors show application of community detection on the time-varying networks constructed from all magnetometers collaborating with the SuperMAG initiative.

    • L. Orr
    • , S. C. Chapman
    •  & W. Guo
  • Article
    | Open Access

    Hurricanes in the Earth’s low atmosphere are known, but not detected in the upper atmosphere earlier. Here, the authors show a long-lasting hurricane in the polar ionosphere and magnetosphere with large energy and momentum deposition despite otherwise extremely quiet conditions.

    • Qing-He Zhang
    • , Yong-Liang Zhang
    •  & Li-Dong Xia
  • Article
    | Open Access

    Seasonally averaged energy input into the ionosphere from geospace is generally considered to be symmetric. Here, the authors show preference for electromagnetic energy input at 450 km altitude into the northern hemisphere, on both the dayside and the nightside, when averaged over season.

    • I. P. Pakhotin
    • , I. R. Mann
    •  & D. J. Knudsen
  • Article
    | Open Access

    Very-Low-Frequency (VLF) communication transmitters, operate worldwide, radiate emissions at particular frequencies 10-30 kHz. Here, the authors show VLF transmitter emissions that leak from the Earth’s ground are primarily responsible for bifurcating the energetic electron belt over 20–100 keV.

    • Man Hua
    • , Wen Li
    •  & Geoffrey D. Reeves
  • Article
    | Open Access

    Electrons in the Van Allen radiation belts can have energies in excess of 7 MeV, however, the energization mechanism is debated. Here, the authors show phase space density peaks in magnetic coordinate space as a way of analyzing satellite observations which demonstrates that local acceleration is capable of heating electrons up to 7 MeV.

    • Hayley J. Allison
    •  & Yuri Y. Shprits
  • Article
    | Open Access

    Magnetic reconnection is a fundamental plasma process of magnetic energy conversion to kinetic energy. Here, the authors show direct evidence of secondary reconnection in the filamentary currents within the flux ropes indicating a significant contribution to energy conversion in the kinetic scale during turbulent reconnection.

    • Shimou Wang
    • , Rongsheng Wang
    •  & Shui Wang
  • Article
    | Open Access

    Theoretical studies suggested that plasmapause surface waves related to the sharp inhomogeneity exist and act as a source of geomagnetic pulsations. Here, the authors show direct observations of a plasmapause surface wave and its impacts during a geomagnetic storm using multi-satellite and ground-based observations.

    • Fei He
    • , Rui-Long Guo
    •  & Wei-Xing Wan
  • Article
    | Open Access

    Various types of plasma waves are generated around electron diffusion regions (EDRs). Here the authors show electron Bernstein waves (EBWs), at the electron-scale boundary of the Hall current reversal near EDR, are sufficiently strong to diffuse electrons and modify electron pressure tensor.

    • W. Y. Li
    • , D. B. Graham
    •  & J. L. Burch
  • Article
    | Open Access

    Chorus waves are crucial on radiation belt dynamics in the space of magnetized planets. Here, the authors show that initially excited single-band chorus waves can quickly accelerate medium energy electrons, and divide the anisotropic electrons into low and high energy components, which subsequently excite two-band chorus waves.

    • Jinxing Li
    • , Jacob Bortnik
    •  & Daniel N. Baker
  • Article
    | Open Access

    Magnetic cavities are universal phenomena existing in cosmic plasma environments. Here Liu et al. show electron scale magnetic cavities in proton scale magnetic cavities observed by Magnetospheric Multiscale (MMS) spacecraft in the Earth’s magnetosheath, and depict the boundary of the electron scale magnetic cavity using particle sounding technique.

    • H. Liu
    • , Q.-G. Zong
    •  & R. Rankin
  • Article
    | Open Access

    Surface waves on the boundary between a magnetosphere and the surrounding plasma might get trapped by the ionosphere forming an eigenmode. Here, Archer et al. show direct observations of this proposed mechanism at Earth’s magnetosphere by analyzing the response to an isolated fast plasma jet detected by the THEMIS satellites.

    • M. O. Archer
    • , H. Hietala
    •  & V. Angelopoulos
  • Article
    | Open Access

    Electron precipitation plays major role in magnetospheric physics and space weather. Here the authors show nonlinear behavior of the wave–particle interaction in the magnetosphere as the evolution of chorus electromagnetic waves detected by the Arase satellite and PWING observatory.

    • Mitsunori Ozaki
    • , Yoshizumi Miyoshi
    •  & Iku Shinohara
  • Article
    | Open Access

    Magnetic reconnection is the process of releasing energy by magnetized and space plasma. Here the authors report experimental observation of magnetic reconnection in laser-produced plasma and the role of electron scaling on reconnection.

    • Y. Kuramitsu
    • , T. Moritaka
    •  & M. Hoshino
  • Article
    | Open Access

    Radial diffusion is the only mechanism considered to accelerate trapped electrons to relativistic energies in Saturn’s magnetic field, forming radiation belts. Here the authors show another mechanism, electron acceleration via Doppler shifted cyclotron resonant interaction with Z-mode waves, which can form radiation belts inside the orbit of Enceladus.

    • E. E. Woodfield
    • , R. B. Horne
    •  & W. S. Kurth
  • Article
    | Open Access

    Remote sensing of geomagnetic fields in mesosphere is both challenging and interesting to explore the magnetic field structures and atomic collision processes. Here the authors demonstrate an atomic magnetometer that utilizes the Larmor frequency in sodium atoms and operates in kilometers range.

    • Felipe Pedreros Bustos
    • , Domenico Bonaccini Calia
    •  & Simon Rochester
  • Article
    | Open Access

    Observations of Jupiter’s magnetosphere provide opportunities to understand how magnetic fields interact with particles. Here, the authors report that the chorus wave power is increased in the vicinity of Europa and Ganymede. The generated waves are able to accelerate particles to very high energy.

    • Y. Y. Shprits
    • , J. D. Menietti
    •  & D. A. Gurnett
  • Article
    | Open Access

    Alfvén waves are fundamental plasma modes that provide a mechanism for the transfer of energy between particles and fields. Here the authors confirm experimentally the conservative energy exchange between Alfvén wave fields and plasma particles via high-resolution MMS observations of Earth’s magnetosphere.

    • Daniel J. Gershman
    • , Adolfo F-Viñas
    •  & James L. Burch
  • Article
    | Open Access

    The interaction between the Earth’s magnetic field and the solar wind results in the formation of a collisionless bow shock. Here, the authors study an even in which the solar wind Mach number remained steadily below one, leading to the evanescence of the bow shock and loss of electrons in the outer belts.

    • Noé Lugaz
    • , Charles J. Farrugia
    •  & Nathan A. Schwadron
  • Article
    | Open Access

    The processes that lead to losses of highly energetic particles from Earth’s radiation belts remain poorly understood. Here the authors compare observations and models of a 2013 event to show that electromagnetic ioncyclotron waves provide the dominant loss mechanism at ultra-relativistic energies.

    • Yuri Y. Shprits
    • , Alexander Y. Drozdov
    •  & Nikita A. Aseev
  • Article
    | Open Access

    Relativistic electrons trapped in the Van Allen radiation belts sometimes exhibit a minimum of their pitch angle distribution at 90°. Here, the authors explain the origin of this phenomenon in terms of chorus and magnetosonic waves through simulations and observations of a geomagnetic storm data.

    • Fuliang Xiao
    • , Chang Yang
    •  & J. B. Blake
  • Article
    | Open Access

    Since the 1970s space missions have observed `equatorial noise' — noise-like plasma waves closely confined to the magnetic equatorial region of Earth s magnetosphere. Here, the authors uncover their structured and periodic frequency pattern, revealing that they are generated by proton distributions.

    • Michael A. Balikhin
    • , Yuri Y. Shprits
    •  & Benjamin Weiss
  • Article
    | Open Access

    Magnetic reconnection is a fundamental energy release process taking place in various astrophysical environments, but it is difficult to observe it directly. Here, the authors provide evidence of three-dimensional magnetic reconnection in a solar eruption using combined perspectives of two spacecraft.

    • J. Q. Sun
    • , X. Cheng
    •  & C. Fang
  • Article
    | Open Access

    Coronal mass ejections from the Sun play an important role in space weather, yet a full understanding of their behaviour remains elusive. Towards this aim, Möstl et al. present a suite of observations showing that an ejection was channelled away from its source region, explaining incorrect forecasts.

    • Christian Möstl
    • , Tanja Rollett
    •  & Bojan Vršnak
  • Article
    | Open Access

    Whistler-mode waves regulate trapped electrons in the magnetosphere, but an accurate determination of their energy budget has remained elusive. This study presents a full analysis of their magnetic and electric field contributions and finds that a large amount of energy is stored in oblique waves.

    • A.V. Artemyev
    • , O.V. Agapitov
    •  & F.S. Mozer
  • Article
    | Open Access

    Although magnetic reconnection is recognized as the dominant mode for solar wind plasma to enter the magnetosphere, Kelvin–Helmholtz waves (KHW) have been suggested to also be involved. Here, the authors use 7 years of THEMIS data to show that KHW occur 19% of the time, and may be important for plasma transport.

    • Shiva Kavosi
    •  & Joachim Raeder
  • Article
    | Open Access

    The origins of the Sun’s periodic activity, such as sunspot cycles, are poorly understood. McIntosh et al.posit that the rotational forcing of the activity bands comprising the 22-year magnetic cycle undergoes shorter-term variations, driving magnetic flux surges that impact solar output on those timescales.

    • Scott W. McIntosh
    • , Robert J. Leamon
    •  & Roger K. Ulrich
  • Article |

    Lunar swirls are high-albedo features on the Moon whose origins are widely debated. Using observations from the Diviner Lunar Radiometer, Glotch et al. present evidence supporting the idea that the swirls arise from abnormal space weathering caused by local magnetic field deflection of solar wind.

    • Timothy D. Glotch
    • , Joshua L. Bandfield
    •  & David A. Paige