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&deg; N, 79.2&deg; E, dip 12.5&deg;) and the E<sub>s</sub> parameters using an ionosonde at a nearby station Sriharikota (...

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Bibliographic Details
Main Authors: A. K. Patra, S. Sripathi, P. B. Rao, K. S. V. Subbarao
Format: Article
Language:English
Published: Copernicus Publications 2005-03-01
Series:Annales Geophysicae
Online Access:https://www.ann-geophys.net/23/773/2005/angeo-23-773-2005.pdf
Description
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&deg; N, 79.2&deg; E, dip 12.5&deg;) and the E<sub>s</sub> parameters using an ionosonde at a nearby station Sriharikota (13.7&deg; N, 80.1&deg; E, dip 12.6&deg;) 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.
ISSN:0992-7689
1432-0576