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| Titel |
High-latitude poynting flux from combined Iridium and SuperDARN data |
| VerfasserIn |
C. L. Waters, B. J. Anderson, R. A. Greenwald, R. J. Barnes, J. M. Ruohoniemi |
| 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 ; 22, no. 8 ; Nr. 22, no. 8 (2004-09-07), S.2861-2875 |
| Datensatznummer |
250014971
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| Publikation (Nr.) |
 copernicus.org/angeo-22-2861-2004.pdf |
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| Zusammenfassung |
| Field-aligned currents convey stress between the magnetosphere and
ionosphere, and the associated low altitude magnetic and electric fields
reflect the flow of electromagnetic energy to the polar ionosphere. We
introduce a new technique to measure the global distribution of high
latitude Poynting flux, S||, by combining electric field
estimates from the Super Dual Auroral Radar Network (SuperDARN) with
magnetic perturbations derived using magnetometer data from the Iridium
satellite constellation. Spherical harmonic methods are used to merge the
data sets and calculate S|| for any magnetic local time (MLT)
from the pole to 60° magnetic latitude (MLAT). The effective spatial
resolutions are 2° MLAT, 2h MLT, and the time resolution is about one
hour due to the telemetry rate of the Iridium magnetometer data. The
technique allows for the assessment of high-latitude net S|| and its
spatial distribution on one hour time scales with two key advantages: (1) it
yields the net S|| including the contribution of neutral
winds; and (2) the results are obtained without recourse to estimates of
ionosphere conductivity. We present two examples, 23 November 1999, 14:00-15:00 UT, and
11 March 2000, 16:00-17:00 UT, to test the accuracy of the technique and to
illustrate the distributions of S|| that it gives. Comparisons
with in-situ S|| estimates from DMSP satellites show agreement
to a few mW/m2 and in the locations of S|| enhancements
to within the technique's resolution. The total electromagnetic energy flux
was 50GW for these events. At auroral latitudes, S|| tends to
maximize in the morning and afternoon in regions less than 5° in MLAT
by two hours in MLT having S||=10 to 20mW/m2 and total
power up to 10GW. The power poleward of the Region 1 currents is about
one-third of the total power, indicating significant energy flux over the polar
cap. |
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