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| Titel |
On the relationship between aspect sensitivity, wave activity, andmultiple scattering centers of mesosphere summer echoes: a case study using coherent radar imaging |
| VerfasserIn |
J.-S. Chen, P. Hoffmann, M. Zecha, J. Röttger |
| 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. 3 ; Nr. 22, no. 3 (2004-03-19), S.807-817 |
| Datensatznummer |
250014803
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| Publikation (Nr.) |
 copernicus.org/angeo-22-807-2004.pdf |
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| Zusammenfassung |
A mesosphere-summer-echo layer, observed by the OSWIN VHF radar (54.1°N, 11.8°E)
with vertical and 7° oblique radar beams, was examined using the method of coherent
radar imaging (CRI). We disclosed the echo events having multiple scattering centers (MSC)
in the radar volume by means of the high angular resolution of the CRI technique and found
that the MSC events occurred more frequently in the upper portion of the echo layer. More
examinations showed that the characteristics were different between the upper and lower
portions of the layer. For example, the differences in echo power between vertical and oblique
beams changed mostly from positive to negative along the increase of altitude, and strong
turbulent echoes were seen in the upper portion of the layer. These observations indicate that
the aspect sensitivity of the echoes became less and less with the increase of altitude.
Moreover, the scattering centers of the echoes were close to zenith for the lower portion of the
layer but were usually several degrees from the zenith for the upper portion of the layer.
Observable wave-like variation in the scattering center was also seen in the upper part of the layer.
Based on these features, we drew some conclusions for this case study: (a) the MSC events
might result from the slanted layer/anisotropic structure tilted by short-wave activities, (b) the
tilt angle of the layer structure could be 6°–10°, causing the echo power received by the
7° oblique beam was larger than or comparable to that received by the vertical beam,
and (c) short-wave activities not only tilted the layer structure, but also induced isotropic
irregularities.
Key words. Meteorology and atmospheric dynamics (middle
atmosphere dynamics). Radio science (interferometry;
instruments and techniques) |
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