Extreme changes in the dayside ionosphere during a Carrington-type magnetic storm Bruce T. Tsurutani, Olga P. Verkhoglyadova, Anthony J. Mannucci, Gurbax S. Lakhina and Joseph D. Huba J. Space Weather Space Clim., 2 (2012) A05 Published online: 13 June 2012 DOI: 10.1051/swsc/2012004