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Ann. Geophys., 26, 117-129, 2008
www.ann-geophys.net/26/117/2008/
© European Geosciences Union 2008
30 MHz radar observations of artificial E region field-aligned plasma irregularities
D. L. Hysell
Earth and Atmospheric Science, Cornell University, Ithaca, NY, USA
Abstract. Artificial E region field aligned irregularities (FAIs) have
been observed during heating experiments at the HAARP facility using a
new 30 MHz coherent scatter radar imager deployed near Homer, Alaska.
Irregularities were observed during brief experiments on three quiet
days in July and August, 2007, when the daytime E region
critical frequency was close to 3 MHz. Irregularities were
consistently generated and detected during experiments with O-mode HF
pumping on zenith with a 1-min on, 1-min off CW modulation. The
scattering cross sections, rise, and fall times of the echoes were
observed as well as their spectral properties. Results were found to
be mainly in agreement with observations from other mid- and
high-latitude sites with some discrepancies. Radar images of the
irregularity-filled volume on one case exhibited clear variations in
backscatter power and Doppler shift across the volume. The images
furthermore show the emergence of a small irregularity-filled region
to the south southwest of the main region in the approximate direction
of magnetic zenith.
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