An Investigation of Turbulent Scatter From the Mesosphere as Observed by Coherent-Scatter Radar
Gibbs, Kenneth Paul
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https://hdl.handle.net/2142/69257
Description
Title
An Investigation of Turbulent Scatter From the Mesosphere as Observed by Coherent-Scatter Radar
Author(s)
Gibbs, Kenneth Paul
Issue Date
1983
Department of Study
Electrical Engineering
Discipline
Electrical Engineering
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Physics, Atmospheric Science
Abstract
Turbulent scatter from the mesosphere is observed using the Urbana coherent-scatter radar. The variation in signal-to-noise ratio as a function of time-of-day is examined. The origin of scattering regions is investigated by comparing the variations in scattered power and Doppler velocity. Nighttime echoes are shown for periods of enhanced electron concentration. The spectrum of the returned signal is studied with a resolution of ten seconds. Spectral information is used to increase altitude resolution and observe the motion of scatterers.
The expected variation in signal-to-noise ratio with solar flux is observed. It is found that variations in the scattered power generally do not correspond to the gravity waves which are simultaneously observed. Turbulent layers are observed at altitudes with high shear in the horizontal velocity and at altitudes with low shear. The ten-second resolution is necessary to distinguish meteor echoes from echoes produced by the advection of a scattering layer through the radar beam. The width of the spectrum of the scattered signal increases with altitude. Fresnel scattering is indicated below 75 km and bulk scattering is indicated above. Scattered layers which move in pairs indicate the generation of turbulence by a Kelvin-Helmholtz instability. Acoustic wave motion is indicated in the data with ten-second resolution.
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