ANGEO Annales Geophysicae ANGEO 1432-0576 Copernicus GmbH Göttingen, Germany 10.5194/angeo-25-1131-2007 Features of stable diffuse arcs observed by means of auroral tomography Dashkevich Zh. V. 1 Ivanov V. E. 1 Khudukon B. Z. 1 Polar Geophysical Institute, 14 Fersmana St., 184209 Apatity, Russia 04 06 2007 25 5 1131 1139 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.ann-geophys.net/25/1131/2007/angeo-25-1131-2007.html The full text article is available as a PDF file from http://www.ann-geophys.net/25/1131/2007/angeo-25-1131-2007.pdf

In this paper we study the spatial distribution of optical volume emission rates and peculiarities of the luminosity intensity within weak diffuse auroral arcs recovered by means of auroral tomography. The tomographic images are obtained from sets of scanning multi-channel photometer data obtained in February 1999 on the Kola Peninsula in Russia at three sites of a chain extending 226 km along the geomagnetic meridian. The 427.8- and 557.7-nm emissions of a 15-s time resolution observed within one hour during low geomagnetic activity are analyzed. We found that the intensity profile of an individual arc along the geomagnetic meridian has an inverted-V-shape. The luminosity maximum altitude decrease by 4–14 km at about 140 km distance in the south-north direction can be observed during two or more diffuse arcs. The parameters of the precipitating electron flux are obtained from an integral equation, which determines the best relationship between the 427.8-nm intensity height profile and an arbitrary particle energy spectrum. A dimensionless function of the energy dissipation is used as the core in the integral equation. The estimated average energy of electron flux, which generated the isolated diffuse arc, is 1–2 keV higher in the central part of the arc in comparison to values at its borders.

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