Two methods to forecast auroral displaysFred Sigernes, Margit Dyrland, Pål Brekke, Sergey Chernouss, Dag Arne Lorentzen, Kjellmar Oksavik and Charles Sterling DeehrJ. Space Weather Space Clim., 1 1 (2011) A03DOI: https://doi.org/10.1051/swsc/2011003