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| Titel |
Meteor fluxes and visual magnitudes from EISCAT radar event rates: a comparison with cross-section based magnitude estimates and optical data |
| VerfasserIn |
A. Pellinen-Wannberg, A. Westman, G. Wannberg, K. Kaila |
| 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 ; 16, no. 11 ; Nr. 16, no. 11, S.1475-1485 |
| Datensatznummer |
250013544
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| Publikation (Nr.) |
 copernicus.org/angeo-16-1475-1998.pdf |
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| Zusammenfassung |
Incoherent scatter radars (ISR) are versatile
instruments for continuous monitoring of ionisation processes in the Earth's
atmosphere. EISCAT, The European Incoherent Scatter facility has proven
effective also in meteor studies. The time resolution of the radar can be
reduced to a few milliseconds, sufficient to resolve the passage of individual
meteors through the narrow ISR beam. Methods for group and phase velocity
determination of the meteoroids and the discrepancy between the results related
to the target behaviour are presented. The radar cross sections of echoes
associated with moving meteoroids ("meteor head echoes") are very
small and increase with decreasing wavelength. The parent meteoroids are found
to have visual magnitudes far below the detection limit of most optical
observations. The equivalent visual magnitude limit of the smallest objects
observed by EISCAT in the current experiments has been estimated by two
different methods, both from the cross-section measurements and from the
measured event rates. Both methods give a limit value of +10 for the smallest
objects while the upper limit is +4. The lower limit of the visual magnitude for
the collocated optical measurement system is +4. Thus the two detection systems
observe two different meteor size ranges, with the radar almost reaching
micrometeorite population. Meteor fluxes estimated from the event rates and the
radar system parameters agree well with previous extrapolated values for this
size range.
Key words. Ionosphere (ionization mechanisms). Radio
science (ionospheric physics). Space plasma physics (ionization processes) |
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