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| Titel |
First mesospheric turbulence study using coordinated rocket and MST radar measurements over Indian low latitude region |
| VerfasserIn |
H. Chandra, H. S. S. Sinha, U. Das, R. N. Misra, S. R. Das, J. Datta, S. C. Chakravarty, A. K. Patra, N. Venkateswara Rao, D. Narayana Rao |
| 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 ; 26, no. 9 ; Nr. 26, no. 9 (2008-09-12), S.2725-2738 |
| Datensatznummer |
250016222
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| Publikation (Nr.) |
 copernicus.org/angeo-26-2725-2008.pdf |
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| Zusammenfassung |
| A campaign to study turbulence in the mesosphere, over low latitudes in
India, using rocket-borne measurements and Indian MST radar, was conducted
during July 2004. A rocket-borne Langmuir probe detected a spectrum of
electron density irregularities, with scale sizes in the range of about 1 m
to 1 km, in 67.5–78.0 km and 84–89 km altitude regions over a low
latitude station Sriharikota (13.6° N, 80.2° E). A rocket-borne
chaff experiment measured zonal and meridional winds about 30 min after the
Langmuir probe flight. The MST radar located at Gadanki (13.5° N,
79.2° E), which is about 100 km west of Sriharikota, also detected the
presence of a strong scattering layer in 73.5–77.5 km region from which
radar echoes corresponding to 3 m irregularities were received. Based on the
region of occurrence of irregularities, which was highly collisional,
presence of significant shears in zonal and meridional components of wind
measured by the chaff experiment, 10 min periodicity in zonal and meridional
winds obtained by the MST radar and the nature of wave number spectra of the
irregularities, it is suggested that the observed irregularities were
produced through the neutral turbulence mechanism. The percentage amplitude
of fluctuations across the entire scale size range showed that the strength
of turbulence was stronger in the lower altitude regions and decreased with
increasing altitude. It was also found that the amplitude of fluctuations
was large in regions of steeper electron density gradients. MST radar
observations showed that at smaller scales of turbulence such as 3 m, (a)
the thickness of the turbulent layer was between 2 and 3 km and (b) and fine
structures, with layer thicknesses of about a km or less were also embedded
in these layers. Rocket also detected 3-m fluctuations, which were very
strong (a few percent) in lower altitudes (67.5 to 71.0 km) and small but
clearly well above the noise floor at higher altitudes. Rocket and radar
results also point to the possibility of existence of thin layers of
turbulence (<450 m). The turbulence parameters estimated from
rocket-borne measurements of electron density fluctuations are consistent
with those determined from MST radar observed Doppler spectra and the
earlier works. |
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