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Nishitani et al. 2004
Nishitani, N., Lester, M., Milan, S.E., Ogawa, T., Sato, N., Yamagishi, H., Yukimatu, A.S. and Rich, F.J. (2004). Unusual ionospheric echoes with high velocity and very low spectral width observed by the SuperDARN radars in the polar cap during high geomagnetic activity. Journal of Geophysical Research 109: doi: 10.1029/2003JA010048. issn: 0148-0227.

The spectral width of the ionospheric backscatter echoes obtained with the SuperDARN radars has been regarded as a useful tool for locating specific ionospheric regions such as the cusp. In this paper we report the presence of ionospheric echoes with high (>450 m/s) Doppler velocity and very low (<60 m/s) spectral width, observed by the CUTLASS and Syowa East and South SuperDARN radars. These echoes have the following characteristics. (1) They have a close correlation with geomagnetic activity such that as the Dst index decreases, the radars tend to observe ionospheric echoes with high Doppler velocity and very low spectral width more frequently. (2) Their existence does not depend on magnetic local time. (3) They are located preferably in the polar cap region, where antisunward convection prevails. (4) They sometimes exist over a wide range, so they are more likely to be F-region rather than E-region echoes. The occurrence of these echoes during active periods is associated with the suppression of the electric field turbulence. The present result appears consistent with the previous paper by Golovchanskaya et al. <2002>, who showed the negative correlation between the electric field turbulence level and geomagnetic activity.

BACKGROUND DATA FILES

Abstract

Keywords
Ionosphere, Electric fields, Ionosphere, Ionosphere/magnetosphere interactions, Ionosphere, Polar cap ionosphere, Magnetospheric Physics, Storms and substorms, Ionosphere, Ionospheric dynamics, SuperDARN, polar cap ionosphere, low spectral width echoes, magnetospheric magnetic field configuration, electric field turbulence, geomagnetic storm
Journal
Journal of Geophysical Research
http://www.agu.org/journals/jb/
Publisher
American Geophysical Union
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