Open Access
J. Space Weather Space Clim.
Volume 4, 2014
Article Number A25
Number of page(s) 10
Published online 15 September 2014

© W.T. Ball et al., Published by EDP Sciences 2014

Licence Creative Commons
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.