ANGEO Annales Geophysicae ANGEO Ann. Geophys. 1432-0576 Copernicus Publications Göttingen, Germany 10.5194/angeo-22-2485-2004 Intense high-altitude auroral electric fields - temporal and spatial characteristics Johansson T. 1 Figueiredo S. 1 Karlsson T. 1 Marklund G. 1 Fazakerley A. 2 Buchert S. 3 Lindqvist P.-A. 1 Nilsson H. 4 Division of Plasma Physics, Alfvén Laboratory, Royal Institute of Technology, SE-100 44 Stockholm, Sweden Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Dorking, Surrey RH5 6NT, UK Swedish Institute of Space Physics, Box 537, SE-751 21 Uppsala, Sweden Swedish Institute of Space Physics, Box 812, SE-981 28 Kiruna, Sweden 14 07 2004 22 7 2485 2495 Copyright: © 2004 T. Johansson et al. 2004 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://angeo.copernicus.org/articles/22/2485/2004/angeo-22-2485-2004.html The full text article is available as a PDF file from https://angeo.copernicus.org/articles/22/2485/2004/angeo-22-2485-2004.pdf

Cluster electric field, magnetic field, and energetic electron data are analyzed for two events of intense auroral electric field variations, both encountered in the Plasma Sheet Boundary Layer (PSBL), in the evening local time sector, and at approximately 5<i>R<sub>E</sub></i> geocentric distance. The most intense electric fields (peaking at 450 and 1600mV/m, respectively) were found to be quasi-static, unipolar, relatively stable on the time scale of at least half a minute, and associated with moving downward FAC sheets (peaking at ~10&mu;A/m<sup>2</sup>), downward Poynting flux (peaking at ~35mW/m<sup>2</sup>), and upward electron beams with characteristic energies consistent with the perpendicular potentials (all values being mapped to 1<i>R<sub>E</sub></i> geocentric distance). For these two events in the return current region, quasi-static electric field structures and associated FACs were found to dominate the upward acceleration of electrons, as well as the energy transport between the ionosphere and the magnetosphere, although Alfv&#233;n waves clearly also contributed to these processes.