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Ann. Geophys., 26, 1837-1850, 2008
www.ann-geophys.net/26/1837/2008/
© European Geosciences Union 2008
Imaging radar observations of Farley Buneman waves during the JOULE II experiment
D. L. Hysell1, G. Michhue1, M. F. Larsen2, R. Pfaff3, M. Nicolls4, C. Heinselman4, and H. Bahcivan4
1Earth and Atmospheric Sciences, Cornell University, Ithaca, NY, USA
2Department of Physics, Clemson University, Clemson, SC, USA
3NASA Goddard Space Flight Center, Greenbelt, MD, USA
4SRI International, Menlo Park, CA, USA
Abstract. Vector electric fields and associated E×B drifts
measured by a sounding rocket in the auroral zone during the NASA
JOULE II experiment in January 2007, are compared with coherent
scatter spectra measured by a 30 MHz radar imager in a common
volume. Radar imaging permits precise collocation of the spectra with
the background electric field. The Doppler shifts and spectral widths
appear to be governed by the cosine and sine of the convection flow
angle, respectively, and also proportional to the presumptive ion
acoustic speed. The neutral wind also contributes to the Doppler
shifts. These findings are consistent with those from the JOULE I
experiment and also with recent numerical simulations of Farley
Buneman waves and instabilities carried out by
Oppenheim et al. (2008). Simple linear analysis of the waves
offers some insights into the spectral moments. A formula relating the
spectral width to the flow angle, ion acoustic speed, and other
ionospheric parameters is derived.
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