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| Titel |
Comparison of the open-closed field line boundary location inferred using IMAGE-FUV SI12 images and EISCAT radar observations |
| VerfasserIn |
B. Hubert, A. T. Aikio, O. Amm, T. Pitkänen, K. Kauristie, S. E. Milan, S. W. H. Cowley, J.-C. Gérard |
| 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 ; 28, no. 4 ; Nr. 28, no. 4 (2010-04-01), S.883-892 |
| Datensatznummer |
250016811
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| Publikation (Nr.) |
 copernicus.org/angeo-28-883-2010.pdf |
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| Zusammenfassung |
| We compare the location of the polar cap boundary (PCB) determined using two
different techniques, and use them as proxies for the open-closed field line
boundary (OCB). Electron temperatures from observations of the EISCAT radar
facility are used to estimate the latitude of the PCB along the meridian of
the EISCAT VHF beam. The second method utilizes global images of proton
aurora obtained by the IMAGE satellite FUV SI12 instrument. These methods
are applied to three different intervals. In two events, the agreement
between the methods is good and the mean of the difference is within the
resolution of the observations. In a third event, the PCB estimated from
EISCAT data is located several degrees poleward of that obtained from the
IMAGE FUV SI12 instrument. Comparison of the reconnection electric field
estimated from the two methods shows that high-resolution measurements both
in time and space are needed to capture the variations in reconnection
electric field during substorm expansion. In addition to the two techniques
introduced above to determine the PCB location, we also use a search for the
location of the reversal of the east-west component of the equivalent
current known as the magnetic convection reversal boundary (MCRB). The MCRB
from the MIRACLE magnetometer chain mainly follows the motion of the polar
cap boundary during different substorm phases, but differences arise near
the Harang discontinuity. |
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