Ring Current Dynamics |
| |
Authors: | Ioannis A Daglis |
| |
Institution: | (1) Institute for Space Applications and Remote Sensing, National Observatory of Athens, Penteli, GR-15236, Athens, Greece |
| |
Abstract: | This chapter reviews the current understanding of ring current dynamics. The terrestrial ring current is an electric current
flowing toroidally around the Earth, centered at the equatorial plane and at altitudes of ∼10,000 to 60,000 km. Enhancements
in this current are responsible for global decreases in the Earth’s surface magnetic field, which have been used to define
geomagnetic storms. Intense geospace magnetic storms have severe effects on technological systems, such as disturbances or
even permanent damage of telecommunication and navigation satellites, telecommunication cables, and power grids. The main
carriers of the ring current are positive ions, with energies from ∼1 keV to a few hundred keV, which are trapped by the geomagnetic
field and undergo an azimuthal drift. The ring current is formed by the injection of ions originating in the solar wind and
the terrestrial ionosphere into the inner magnetosphere. The injection process involves electric fields, associated with enhanced
magnetospheric convection and/or magnetospheric substorms. The quiescent ring current is carried mainly by protons of predominantly
solar wind origin, while active processes in geospace tend to increase the abundance (both absolute and relative) of O+ ions, which are of ionospheric origin. During intense geospace magnetic storms, the O+ abundance increases dramatically. This increase has been observed to occur concurrently with the rapid intensification of
the ring current in the storm main phase and to result in O+ dominance around storm maximum. This compositional change can affect several dynamic processes, such as species-and energy-dependent
charge-exchange and wave-particle scattering loss. |
| |
Keywords: | Magnetic storms ring current substorms magnetosphere-ionosphere coupling particle acceleration inner magnetosphere plasma sheet |
本文献已被 SpringerLink 等数据库收录! |
|