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| Titel |
Some new features of electron density irregularities over SHAR during strong spread F |
| VerfasserIn |
S. Raizada, H. S. S. Sinha |
| 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 ; 18, no. 2 ; Nr. 18, no. 2, S.141-151 |
| Datensatznummer |
250013902
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| Publikation (Nr.) |
 copernicus.org/angeo-18-141-2000.pdf |
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| Zusammenfassung |
An RH-560 rocket flight was conducted from
Sriharikota rocket range (SHAR) (14°N, 80°E, dip latitude 5.5°N) to study
electron density and electric field irregularities during spread F. The rocket
was launched at 2130 local time (LT) and it attained an apogee of 348 km.
Results of electron density fluctuations are presented here. Two extremely sharp
layers of very high electron density were observed at 105 and 130 km. The
electron density increase in these layers was by a factor of 50 in a vertical
extent of 10 km. Large depletions in electron density were observed around 175
and 238 km. Both sharp layers as well as depletions were observed also during
the descent. The presence of sharp layers and depletions during the ascent and
the descent of the rocket as well as an order of magnitude less electron
density, in 150-300 km region during the descent, indicate the presence of
strong large-scale horizontal gradients in the electron density. Some of the
valley region irregularities (165-178 km), in the intermediate scale size range,
observed during this flight, show spectral peaks at 2 km and can be interpreted
in terms of the image striation theory suggested by Vickrey et al. The
irregularities at 176 km do not exhibit any peak at kilometer scales and appear
to be of new type. The growth rate of intermediate scale size irregularities,
produced through generalized Rayleigh Taylor instability, was calculated for the
200-330 km altitude, using observed values of electron density gradients and an
assumed vertically downward wind of 20 ms-1. These growth rate
calculations suggest that the observed irregularities could be produced by the
gradient drift instability.
Key words: Ionosphere (equatorial ionosphere;
ionospheric irregularities) - Radio science (ionospheric physics) |
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