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| Titel |
Feasibility study on Generalized-Aurora Computed Tomography |
| VerfasserIn |
Y.-M. Tanaka, T. Aso, B. Gustavsson, K. Tanabe, Y. Ogawa, A. Kadokura, H. Miyaoka, T. Sergienko, U. Brandstrom, I. Sandahl |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 29, no. 3 ; Nr. 29, no. 3 (2011-03-15), S.551-562 |
| Datensatznummer |
250016991
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| Publikation (Nr.) |
 copernicus.org/angeo-29-551-2011.pdf |
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| Zusammenfassung |
| Aurora Computed Tomography (ACT) is a method for retrieving the
three-dimensional (3-D) distribution of the volume emission rate from
monochromatic auroral images obtained simultaneously by a multi-point camera
network. We extend this method to a Generalized-Aurora Computed Tomography
(G-ACT) that reconstructs the energy and spatial distributions of
precipitating electrons from multi-instrument data, such as ionospheric
electron density from incoherent scatter radar, cosmic noise absorption
(CNA) from imaging riometers, as well as the auroral images. The purpose of
this paper is to describe the reconstruction algorithm involved in this
method and to test its feasibility by numerical simulation. Based on a
Bayesian model with prior information as the smoothness of the electron
energy spectra, the inverse problem is formulated as a maximization of
posterior probability. The relative weighting of each instrument data is
determined by the cross-validation method. We apply this method to the
simulated data from real instruments, the Auroral Large Imaging System
(ALIS), the European Incoherent Scatter (EISCAT) radar at Tromsø, and the
Imaging Riometer for Ionospheric Study (IRIS) at Kilpisjärvi. The results
indicate that the differential flux of the precipitating electrons is well
reconstructed from the ALIS images for the low-noise cases. Furthermore, we
demonstrate in a case study that the ionospheric electron density from the
EISCAT radar is useful for improving the reconstructed electron flux. On the
other hand, the incorporation of CNA data into this method is difficult at
this stage, because the extension of energy range to higher energy causes a
difficulty in the reconstruction of the low-energy electron flux.
Nevertheless, we expect that this method may be useful in analyzing
multi-instrument data and, in particular, 3-D data, which will be obtained
in the upcoming EISCAT_3D. |
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