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| Titel |
Meteor trail characteristics observed by high time resolution lidar |
| VerfasserIn |
Y. J. Liu, J. M. C. Plane, B. R. Clemesha, J. H. Wang, X. W. Cheng |
| 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 ; 32, no. 10 ; Nr. 32, no. 10 (2014-10-29), S.1321-1332 |
| Datensatznummer |
250121125
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| Publikation (Nr.) |
 copernicus.org/angeo-32-1321-2014.pdf |
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| Zusammenfassung |
| We report and analyse the characteristics of 1382 meteor trails based on a
sodium data set of ~ 680 h. The observations were made at Yanqing
(115.97° E, 40.47° N), China by a ground-based Na
fluorescence lidar. The temporal resolution of the raw profiles is 1.5 s and
the altitude resolution is 96 m. We discover some characteristics of meteor
trails different from those presented in previous reports. The occurrence
heights of the trails follow a double-peak distribution with the peaks at
~ 83.5 km and at ~ 95.5 km, away from the peak height of the
regular Na layer. 4.7% of the trails occur below 80 km, and 3.25%
above 100 km. 75% of the trails are observed in only one 1.5 s
profile, suggesting that the dwell time in the laser beam is not greater than
1.5 s. The peak density of the trails as a function of height is similar to
that of the background sodium layer. The raw occurrence height distribution
is corrected taking account of three factors which affect the relative
lifetime of a trail as a function of height: the meteoroid velocity (which
controls the ratio of Na/Na+ ablated); diffusional spreading of
the trail; and chemical removal of Na. As a result, the bi-modal distribution
is more pronounced. Modelling results show that the higher peak corresponds to
a meteoroid population with speeds between 20 and
30 km s−1, whereas the
lower peak should arise from much slower particles in a near-prograde orbit.
It is inferred that most meteoroids in this data set have masses of
~ 1 mg, in order for ablation to produce sufficient Na atoms to be
detected by lidar. Finally, the evolution of longer-duration meteor trails is
investigated. Signals at each altitude channel consist of density enhancement
bursts with the growth process usually faster than the decay process, and
there exists a progressive phase shift among these altitude channels. |
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