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Reversed flow events in the cusp ionosphere detected by SuperDARN HF radars

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posted on 2012-10-24, 08:54 authored by K. Oksavik, J. I. Moen, E. H. Rekaa, H. C. Carlson, M. Lester
[1] We present several examples of reversed flow events (RFEs) from the cusp ionosphere. RFEs are 100–200 km wide flow channels opposing the background plasma convection. RFEs were discovered a few years ago by the incoherent scatter European Incoherent Scatter Svalbard Radar. In this paper we show that coherent scatter Super Dual Auroral Radar Network (SuperDARN) HF radars can also see RFEs. We report a close relationship between RFEs and the development of HF backscatter power and spectral width. Wide spectra were seen near the edges of the RFEs (i.e., associated with the flow shear), and there was a significant increase in SuperDARN HF backscatter power when the RFE expanded. This increase in power is much faster than anticipated from the gradient drift instability alone, supporting the hypothesis that RFE flow shears foster rapid growth of Kelvin-Helmholtz instabilities. That decameter-scale irregularities form so rapidly should be an important guide to the development of instability theory for cascade of plasma irregularities from larger to smaller scale sizes.

History

Citation

Journal of Geophysical Research-SPACE PHYSICS, 2011, 116

Version

  • VoR (Version of Record)

Published in

Journal of Geophysical Research-SPACE PHYSICS

Publisher

American Geophysical Union (AGU); Wiley

issn

0148-0227

Copyright date

2011

Available date

2012-10-24

Publisher version

http://onlinelibrary.wiley.com/doi/10.1029/2011JA016788/abstract

Language

en

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