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Ann. Geophys., 22, 2023-2031, 2004
www.ann-geophys.net/22/2023/2004/
© European Geosciences Union 2004
Ionospheric propagation effects on spectral widths measured by SuperDARN HF radars
X. Vallières, J.-P. Villain, C. Hanuise, and R. André
LPCE/CNRS, 3A Av. de la Recherche Scientifique, 45071 Orléans Cedex 2, France
Abstract. SuperDARN HF radars provide a global survey of the large-scale convection
transversely to the Earth's magnetic field in the high-latitude ionosphere.
In addition to the mean plasma velocity, this network also provides
measurements of spectral widths which are related to the level of turbulence
of the sounded plasma. There is an increasing interest in using spectral
widths in geophysical studies, since they are used to monitor the footprints
of several magnetospheric regions. In the present paper, we show the effect
of radio wave propagation through a typical turbulent ionosphere on spectral
widths measured by SuperDARN radars. This effect has already been evidenced
experimentally in a previous paper. Here, we model the effects of meso-scale
structures on a radar wave front and study their impact on a typical
measurement. Numerical simulations reproduce the effect evidenced
experimentally and show the role of meso-scale structures (1-10km) in the
systematic bias that affects spectral width values. As in experimental data,
this effect is shown to be increasing with decreasing radar frequency.
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