Asset Publisher

Temporal evolution of the electric field accelerating electrons away from the auroral ionosphere

Temporal evolution of the electric field accelerating electrons away from the auroral ionosphere

Publication date: 13 December 2001

Authors: Marklund, G. T., et al.

Journal: Nature
Volume: 414
Issue: 6865
Page: 724-727
Year: 2015

Copyright: Nature Publishing Group

The bright night-time aurorae that are visible to the unaided eye are caused by electrons accelerated towards Earth by an upward-pointing electric field. On adjacent geomagnetic field lines the reverse process occurs: a downward-pointing electric field accelerates electrons away from Earth. Such magnetic-field-aligned electric fields in the collisionless plasma above the auroral ionosphere have been predicted, but how they could be maintained is still a matter for debate. The spatial and temporal behaviour of the electric fields — a knowledge of which is crucial to an understanding of their nature — cannot be resolved uniquely by single satellite measurements. Here we report on the first observations by a formation of identically instrumented satellites crossing a beam of upward-accelerated electrons. The structure of the electric potential accelerating the beam grew in magnitude and width for about 200 s, accompanied by a widening of the downward-current sheet, with the total current remaining constant. The 200-s timescale suggests that the evacuation of the electrons from the ionosphere contributes to the formation of the downward-pointing magnetic-field-aligned electric fields. This evolution implies a growing load in the downward leg of the current circuit, which may affect the visible discrete aurorae.

Link to publication
Last Update: Sep 1, 2019 8:34:50 AM
17-Oct-2021 10:23 UT

ShortUrl Portlet

Shortcut URL

https://sci.esa.int/s/ABky9Kw

Images And Videos

Related Publications

Related Links

Documentation