Please use this identifier to cite or link to this item: http://hdl.handle.net/2381/39333
Title: E-region echo characteristics governed by auroral arc electrodynamics
Authors: Milan, S. E.
Sato, N.
Lester, M.
Murata, Y.
Shinkai, Y.
Doi, H.
Frey, H. U.
Saemundsson, T.
First Published: 31-Jul-2003
Publisher: European Geosciences Union (EGU), Copernicus Publications, Springer Verlag (Germany)
Citation: Annales Geophysicae, 2003, 21 (7), pp. 1567-1575 (9)
Abstract: Observations of a pair of auroral arc features by two imagers, one ground- and one space-based, allows the associated field-aligned current (FAC) and electric field structure to be inferred. Simultaneous observations of HF radar echoes provide an insight into the irregularity-generating mechanisms. This is especially interesting for the E-region echoes observed, which form the focus of our analysis, and from which several conclusions can be drawn, summarized as follows. Latitudinal variations in echo characteristics are governed by the FAC and electric field background. Particularly sharp boundaries are found at the edges of auroral arcs. Within regions of auroral luminosity, echoes have Doppler shifts below the ion-acoustic speed and are proportional to the electric field, suggesting scatter from gradient drift waves. Regions of downward FAC are associated with mixed high and low Doppler shift echoes. The high Doppler shift component is greatly in excess of the ion-acoustic speed, but seems to be commensurate with the driving electric field. The low Doppler shift component appears to be much depressed below expectations.
DOI Link: 10.5194/angeo-21-1567-2003
ISSN: 0992-7689
eISSN: 1432-0576
Links: http://www.ann-geophys.net/21/1567/2003/
http://hdl.handle.net/2381/39333
Version: Publisher Version
Status: Peer-reviewed
Type: Journal Article
Rights: © Author(s) 2003. This work is distributed under the Creative Commons Attribution 3.0 License.
Appears in Collections:Published Articles, Dept. of Physics and Astronomy

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