Quiescent Discrete Auroral Arcs: A Review of Magnetospheric Generator Mechanisms

  title={Quiescent Discrete Auroral Arcs: A Review of Magnetospheric Generator Mechanisms},
  author={Joseph, E. Borovsky and Joachim Birn and Marius M. Echim and Shigeru Fujita and Robert L. Lysak and David J. Knudsen and Octav Marghitu and Antonius Otto and Tomo-Hiko Watanabe and Takashi Tanaka},
  journal={Space Science Reviews},
One of the longstanding questions of space science is: How does the Earth’s magnetosphere generate auroral arcs? A related question is: What form of energy is extracted from the magnetosphere to drive auroral arcs? Not knowing the answers to these questions hinders our ability to determine the impact of auroral arcs on the magnetospheric system. Magnetospheric mechanisms for driving quiescent auroral arcs are reviewed. Two types of quiescent arcs are (1) low-latitude non-Alfvenic (growth-phase… 
A Mission Concept to Determine the Magnetospheric Causes of Aurora
Insufficiently accurate magnetic-field-line mapping between the aurora and the equatorial magnetosphere prevents us from determining the cause of many types of aurora. An important example is the
Quiet, Discrete Auroral Arcs: Acceleration Mechanisms
The theory of the acceleration of auroral particles is reviewed, focusing on developments in the last 15 years. We discuss elementary plasma physics processes leading to acceleration of electrons to
A Method to Estimate the Physical Properties of Magnetospheric Generators From Observations of Quiet Discrete Auroral Arcs
We discuss a method to estimate the properties of a magnetospheric generator using a quasi‐electrostatic magnetosphere‐ionosphere coupling model and in situ or remote sensing observations of discrete
Sliding Contacts in Planetary Magnetospheres
Sliding layers are formed in the ionosphere, on separatrix surfaces, at the magnetopauses and boundaries of stellar astrospheres, and at the Alfvén radius in the equatorial magnetosphere of rapidly rotating strongly magnetized giant planets.
On the Saturation (or Not) of Geomagnetic Indices
  • J. Borovsky
  • Physics
    Frontiers in Astronomy and Space Sciences
  • 2021
Most geomagnetic indices are associated with processes internal to the magnetosphere-ionosphere system: convection, magnetosphere-ionosphere current systems, particle pressure, ULF wave activity,
Small-Scale Dynamic Aurora
The observed properties of flickering auroras, vortex motions, and filamentary structures are summarized, and the development of fundamental theories, such as dispersive Alfvén waves (DAWs), plasma instabilities in the auroral acceleration region, ionospheric feedback instabilities (IFI), and the Ionospheric Alfván resonator (IAR), are summarized.
Substorm Current Wedge: Energy Conversion and Current Diversion
Using a magnetohydrodynamic simulation of magnetotail reconnection, flow bursts, and dipolarization, we further investigate the current diversion and energy flow and conversion associated with the


Quiet, Discrete Auroral Arcs—Observations
Quiet, discrete auroral arcs are an important and fundamental consequence of solar wind-magnetosphere interaction. We summarize the current standing of observations of such auroral arcs. We review
Auroral arcs: Result of the interaction of a dynamic magnetosphere with the ionosphere
A model of auroral arcs is presented. It is assumed that the magnetic field lines into the auroral oval are loaded with kev electrons, that precipitating auroral electrons locally constitute a net
A theory of quiet auroral arcs
Being fed by the large-scale magnetospheric convection, the coupled ionosphere-magnetosphere system is subject to a feedback instability for a conjugate perturbation elongating in the east-west
Six auroral generators: A review
[1] The paper reviews generator processes and configurations of six types of auroral arcs: embedded arcs, Alfvenic arcs, onset arcs, poleward arcs during substorms, auroral streamers, and auroral
Equatorward moving arcs and substorm onset
[1] Key observations of phenomena during the growth phase of a substorm are being reviewed with particular attention to the equatorward motion of the hydrogen and electron arcs. The dynamic role of
Review of Auroral Currents and Auroral Arcs
Discrete auroral arcs involve both magnetic-field-aligned electric fields and currents. Theories agree that the currents close below the arcs through the E region ionosphere. Postulated closures
Quiet auroral arcs and electrodynamic coupling between the ionosphere and the magnetosphere, 1
The magnetosphere-ionosphere system associated with the nighttime auroral region is considered for quiet conditions, and it is shown that in the presence of an electric field an ionospheric electron
Auroral arc thicknesses as predicted by various theories
Twenty-two theoretical mechanisms for auroral arcs are examined (12 electron-acceleration mechanisms and 10 generator mechanisms) and a characteristic auroral-arc thickness is worked out for each
Poleward arcs of the auroral oval during substorms and the inner edge of the plasma sheet
[1] An analytical model for the connection between the near-Earth edge of the plasma sheet at substorm onset and the auroral arcs at the poleward edge of the auroral oval is presented. The connection
Auroral arcs as sites of magnetic stress release
[1] An analytical model is presented for auroral arcs as the result of a fast release of magnetic shear stresses. The shear stresses are set up by a longitudinal convection that is driven by pressure