angeo-22-169-2004.pdf (827.73 kB)
Download file

High resolution observations of spectral width features associated with ULF wave signatures in artificial HF radar backscatter

Download (827.73 kB)
journal contribution
posted on 08.12.2009, 16:24 by D. M. Wright, Tim K. Yeoman, L. J. Baddeley, J. A. Davies, R. Dhillon, M. Lester, Steve E. Milan, E. E. Woodfield
The EISCAT high power heating facility at Tromsø, northern Norway, has been utilised to generate artificial radar backscatter in the fields of view of the CUTLASS HF radars. It has been demonstrated that this technique offers a means of making very accurate and high resolution observations of naturally occurring ULF waves. During such experiments, the usually narrow radar spectral widths associated with artificial irregularities increase at times when small scale-sized (high m-number) ULF waves are observed. Possible mechanisms by which these particle-driven high-m waves may modify the observed spectral widths have been investigated. The results are found to be consistent with Pc1 (ion-cyclotron) wave activity, causing aliasing of the radar spectra, in agreement with previous modelling work. The observations also support recent suggestions that Pc1 waves may be modulated by the action of longer period ULF standing waves, which are simultaneously detected on the magnetospheric field lines. Drifting ring current protons with energies of ∼ 10keV are indicated as a common plasma source population for both wave types.

History

Citation

Annales Geophysicae, 2004, 22(1), pp.169-182

Published in

Annales Geophysicae

Publisher

European Geosciences Union (EGU), Copernicus Publications, Springer Verlag (Germany)

Copyright date

2004

Available date

08/12/2009

Publisher version

http://www.ann-geophys.net/22/169/2004/angeo-22-169-2004.html

Language

en