Simultaneous VHF radar backscatter and ionosonde observations of low-latitude E region
The first results of simultaneous observations made on the low-latitude field-aligned irregularities (FAI) using the MST radar located at Gadanki (13.5° N, 79.2° E, dip 12.5°) and the E<sub>s</sub> parameters using an ionosonde at a nearby station Sriharikota (...
Main Authors: | , , , |
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Format: | Article |
Language: | English |
Published: |
Copernicus Publications
2005-03-01
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Series: | Annales Geophysicae |
Online Access: | https://www.ann-geophys.net/23/773/2005/angeo-23-773-2005.pdf |
Summary: | The first results of simultaneous observations made on the low-latitude
field-aligned irregularities (FAI) using the MST radar located at Gadanki
(13.5° N, 79.2° E, dip 12.5°) and the E<sub>s</sub> parameters
using an ionosonde at a nearby station Sriharikota (13.7° N, 80.1° E,
dip 12.6°) are presented. The observations show that while the
height of the most intense radar echoes is below the virtual height of
E<sub>s</sub> (h'E<sub>s</sub>) during daytime, it is found to be either below
or above during nighttime. The strength of the FAI is better correlated with
the top penetration frequency (f<sub>t</sub>E<sub>s</sub>) and the blanketing frequency
(f<sub>b</sub>E<sub>s</sub>) during the night (r=0.4 in both cases) as compared to the
day (r=0.35 and -0.04, respectively). Furthermore, the signal strength of FAI
is reasonably correlated with (f<sub>t</sub>E<sub>s</sub>-f<sub>b</sub>E<sub>s</sub>) during daytime
(r=0.59) while very poorly correlated during nighttime (r=0.18). While
the radar observations in general appear to have characteristics close to
that of mid-latitudes, the relationship of these with the E<sub>s</sub> parameters
are poorer than that of mid-latitudes. The observations reported here,
nevertheless, are quite consistent with the expectations based on the gradient
drift instability mechanism. |
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ISSN: | 0992-7689 1432-0576 |