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A statistical study of the location and motion of the HF radar cusp

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journal contribution
posted on 2017-01-24, 11:29 authored by T. K. Yeoman, P. G. Hanlon, K. A. McWilliams
The large-scale and continuous monitoring of the ionospheric cusp region offered by HF radars has been exploited in order to examine the statistical location and motion of the equatorward edge of the HF radar cusp as a function of the upstream IMF BZ component. Although a considerable scatter is seen, both parameters have a clear influence from the north-south component of the IMF. Excellent agreement is achieved with previous observations from low altitude spacecraft data. The HF radar cusp region is seen to migrate equatorward at a rate of 0.02° min-1 nT-1 under IMF BZ south conditions, but remains static for IMF BZ north. The motion of the cusp implies an addition of magnetic flux of ~ 2 × 104 Wbs-1 nT-1 under IMF BZ south conditions, equivalent to a reconnection voltage of 20 kV nT-1, which is consistent with previous estimates from case studies on both the dayside and nightside regions.


The CUTLASS HF radars are deployed and operated by the University of Leicester, and are jointly funded by the UK Particle Physics and Astronomy Research Council (Grant no. PPA/R/R/1997/00256), the Finnish Meteorological Institute, and the Swedish Institute for Space Physics. KAM gratefully acknowledges funding from the British Council. We would like to thank the ACE Science Center and N. F. Ness for providing the ACE magnetic field data.



Annales Geophysicae, 2002, 20 (2), pp. 275-280 (6)

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/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/Department of Physics and Astronomy


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Annales Geophysicae


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





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