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Sripathi et al. 2003
Sripathi, S., Patra, A.K., Sivakumar, V. and Rao, P.B. (2003). Shear instability as a source of the daytime quasi-periodic radar echoes observed by the Gadanki VHF radar. Geophysical Research Letters 30: doi: 10.1029/2003GL017544. issn: 0094-8276.

High-resolution observations of the daytime quasi-periodic (QP) structures of the lower E region irregularities made using the Gadanki VHF radar are presented. The structures are found to display striations with negative altitude rates of ~10 m s-1 and periods of 1--3 minutes. More importantly, these structures are found to be associated with a descending irregularity layer having descent rate of ~0.3 m s-1. The characteristics of these structures although resemble closely to that of nighttime low altitude structures observed earlier at Gadanki as well as at mid-latitudes, the periodicities observed during daytime are found to be higher than that observed during nighttime. The Doppler velocities are mostly in the range -20--10 m s-1 and exhibit remarkable shear corresponding to the echoes of larger periodicities. The echoes being mostly confined to the collision dominated lower E region, it is possible to derive meridional neutral wind and the derived wind shows remarkable shear. It is proposed that the Kelvin-Helmholtz instability is the most likely mechanism responsible for the observed structures presented in this paper.

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Abstract

Keywords
Ionosphere, Equatorial ionosphere, Ionosphere, Ionospheric dynamics, Ionosphere, Midlatitude ionosphere, Ionosphere, Plasma waves and instabilities, Ionosphere, Wave propagation
Journal
Geophysical Research Letters
http://www.agu.org/journals/gl/
Publisher
American Geophysical Union
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