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| Titel |
Measurements of atmospheric turbulence with the dual-beamwidth method using the MST radar at Gadanki, India |
| VerfasserIn |
G. D. Nastrom, P. B. Rao, V. Sivakumar |
| 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. 9 ; Nr. 22, no. 9 (2004-09-23), S.3291-3297 |
| Datensatznummer |
250015008
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| Publikation (Nr.) |
 copernicus.org/angeo-22-3291-2004.pdf |
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| Zusammenfassung |
| A brief experiment was conducted during 24-29 April and 9-10 May 2002,
using the MST radar at Gadanki, India, to test the dual-beamwidth method of
estimating the turbulence kinetic energy (TKE). Because the beamwidth can be
modified on only one polarization at a time at Gadanki, an elliptical beam
was used with a modified dual-beamwidth analysis. Estimates of the TKE from
the dual-beamwidth method and the traditional method are very similar in
regions of light winds (<~10ms-1). In regions of stronger wind
(>~15ms-1) the traditional method often gives TKE<0 because
the beam-broadening correction is greater than the observed spectral width.
It is suggested that some of the problems with the traditional method are
due to the uncertainty in the effective width of the radar beam. In all regions
the modified dual-beamwidth method gives TKE>0 on the beam parallel to the
prevailing wind; on this beam the estimates depend only on the ratio of the
beamwidths, which is presumably well-known, and the observed spectral
widths. The values of TKE from the dual-beamwidth method are approximately
constant with height at 0.2m2s-2 from about 5 to 7.5km during
the afternoon during both April and May (all April observations were made
between 9:00 and 17:00 local time), and then decrease rapidly to about 0.02m2s-2
by about 9km. The data from May extend over one full
diurnal period and the diurnal range of TKE during this period is found to
be about 5dB below about 12km and from about 15 to 19km, near the
tropopause, with maximum values during local afternoon. |
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