Introduction to the thematic series “Coupling of the magnetosphere–ionosphere system”
Yao et al. Geosci. Lett.
Introduction to the thematic series “Coupling of the magnetosphere-ionosphere system”
Z. H. Yao 0
K. R. Murphy 2
I. J. Rae 1
N. Balan 3
0 Laboratoire de Physique Atmospherique et Planetaire, STAR Institute, Universite de Liege , Liege , Belgium
1 UCL Mullard Space Science Laboratory , Dorking RH5 6NT , UK
2 Goddard Space Flight Center , NASA, Greenbelt , USA
3 INPE, São José dos Campos, SP CEP 12227-010 , Brazil
This thematic series contains 4 papers mostly presented at the 2016 AOGS meeting in Beijing. The four papers investigate four key regions in the magnetosphere-ionosphere coupling process: mid-tail magnetosphere, near-Earth magnetosphere, inner magnetosphere, and the polar ground region. Guo et al. (Geosci Lett 4:18, 2017) study the current system in reconnection region using 2.5D particle-in-cell simulations. Yao et al. (Geosci Lett 4:8, 2017) use conjugate measurements from ground auroral imagers and in situ THEMIS spacecraft to reveal the mechanism for the wave-like auroral structures prior to substorm onset. Zhang et al. (Geosci Lett 4:20, 2017) investigate the profiles of resonance zone and resonant frequency in the Landau resonance between radiation belt electrons and magnetosonic waves and between protons and cyclotron waves. Rae et al. (Geosci Lett 4:23, 2017) determine the relative timing between sudden increases in amplitude, or onsets, of different ultra-low-frequency wave bands during substorms.
The dynamic coupling between the magnetosphere and
the ionosphere system is crucial for understanding energy
dissipation in the Earth system and in both solar system
planets and exoplanets. The Earth’s polar ionosphere
couples to the entire magnetosphere; the distant tail > 25 RE,
near/mid-Earth magnetotail 6.6–25 RE, and inner
magnetosphere < 6.6 RE. Particle acceleration, field-aligned
current generation, and ground magnetic perturbations are
the most pivotal and challenging in understanding how
the magnetosphere–ionosphere system is coupled. The
past two decades have seen the development and launch
of a number of space missions and deployment of ground
stations dedicated to the investigation of a particular link
in the chain of interactions between magnetosphere and
ionosphere. With these new assets, it is now possible to
understand the energy conversion process between
magnetosphere and ionosphere on both global and localized
scales with conjugate measurements in all key regions,
i.e., the mid-magnetotail, near-Earth magnetotail,
ionosphere, and Earth’s polar ground.
The thematic series of Geoscience Letters are mostly
based on presentations from the session on the same
topic (ST06: Magnetosphere–Ionosphere Coupling
Dynamics) organized at the Asia Oceania Geosciences
Society (AOGS) General Assembly held in Beijing during
July 31–August 5, 2016. The papers are organized in the
order from the outer magnetosphere to the inner
magnetosphere and the ionosphere.
Energy in driving terrestrial magnetospheric dynamics
originates from the solar wind and is stored in the
magnetosphere via magnetopause reconnection
. In the magnetotail, reconnection is essential in
energizing particles, producing high-speed flows, and the
formation of plasmoids. How electrons are accelerated
via reconnection and how reconnection outflow drives
magnetotail dynamics are two fundamental topics in
terrestrial magnetosphere field.
From 2.5D particle-in-cell (PIC) simulations,
et al. (2017
) examine current systems forming near the
electron separatrix and investigating a non-gyrotropic
electron distribution. These authors suggest that a
dramatic change in the orientation of the electron velocity
could be a diagnostic to detect the electron separatrix.
In the reconnection exhaust region,
Guo et al. (2017
show that ions are the main carriers for the out-of-plane
current, while the parallel current is mainly carried by
Near‑Earth and inner magnetosphere
Reconnection outflow from night-side tail reconnection
propagates from mid-tail to near-Earth magnetotail and
inner magnetosphere. The propagation of these flows
causes perturbations of plasma and fields, which can lead
to particle energization in the inner region.
A major impact of the reconnection outflow is caused
by its braking and deceleration in the near-Earth
magnetotail. These include flux pileup
(e.g., Shiokawa et al.
and the development of plasma instabilities
(e.g., Lui 1991)
in the inner magnetosphere. By
analyzing simultaneous measurements from the near-Earth
Yao et al. (2017
) reveal that a kinetic-scale
ballooning instability was excited at the arrival of a
reconnection outflow. This caused the development of
wave-like auroral structures in the atmosphere. Their
analysis shows consistent wavelength from aurora and
in situ measurements. Moreover, they also present
similar wave-like auroral feature at Saturn and Jupiter, which
may imply that a common process exists at other planets.
Zhang et al. (2017
) investigate the profiles of resonance
zone and resonant frequency in the Landau resonance
between radiation belt electrons and magnetosonic
waves and between protons and cyclotron waves. Their
results demonstrate that resonant interactions between
magnetosonic waves and magnetospheric charged
particles depend heavily on L-shell, wave normal angle, kinetic
energy, and equatorial pitch angle of the particles.
Resonance zones for the Landau resonance between
magnetosonic waves and radiation belt electrons are confined to a
very narrow (mostly less than 1°) extent of magnetic
latitude, which tends to shift to lower latitudes with
increasing equatorial pitch angle and decreasing electron energy.
Ground magnetic perturbation
Measurements of ground magnetic perturbations provide
a unique view for understanding the global development
of ionospheric and magnetospheric current system
during a substorm.
Rae et al. (2017
) determine the relative
timing between sudden increases in amplitude, or onsets,
of different ultra-low-frequency (ULF) wave bands
during substorms. They show that differing onset times and
spatial expansion exist for Pi1, Pi1-2, and Pi2 waves in the
ionosphere during substorms. Their results demonstrate
how careful analysis of ULF waves during substorm onset
can provide vital information on the physical processes
occurring and time history of these processes through
All the authors acted as Guest Editors for the contributed papers. The
Introduction was first drafted by ZY but all the authors read and agreed the
contents. All authors read and approved the final manuscript.
We thank all the authors who presented the papers at the AOGS meeting and
contributed to this thematic collection. We also thank reviewers for improving
the quality of papers. ZHY is a Marie-Curie COFUND research fellow, cofunded
The authors declare that they have no competing interests.
Availability of data and materials
All the papers introduced here have been published.
Asia and Oceania Geoscience Society contributed Article Processing Charges
for this Introduction, as well as most of the papers.
Springer Nature remains neutral with regard to jurisdictional claims in
published maps and institutional affiliations.
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Guo RL , Pu ZY , Wei Y ( 2017 ) Current structure and flow pattern on the electron separatrix in reconnection region . Geosci Lett 4 : 18 . https://doi. org/10.1186/s40562-017-0085-4
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Rae IJ , Murphy KR , Watt CEJ , Mann IR , Yao ZH , Kalmoni NME , Forsyth C , Milling DK ( 2017 ) Using ultra-low frequency waves and their characteristics to diagnose key physics of substorm onset . Geosci Lett 4 : 23 . https://doi. org/10.1186/s40562-017-0089-0
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Yao ZH , Pu ZY , Rae IJ , Radioti A , Kubyshkina MV ( 2017 ) Auroral streamer and its role in driving wave-like pre-onset aurora . Geosci Lett 4 : 8 . https://doi. org/10.1186/s40562-017-0075-6
Zhang WX , Zhou RX , Yi J , Gu XD , Ni BB , Zheng CY , Hua M ( 2017 ) Resonance zones for interactions of magnetosonic waves with radiation belt electrons and protons . Geosci Lett 4 : 20 . https://doi.org/10.1186/ s40562-017-0086-3