Ionospheric disturbances in a large area of the terrestrial globe by two strong solar flares of September 6, 2017, the strongest space weather events in the last decade

P. R. Fagundes, Michael Pezzopane, John Bosco Habarulema, K. Venkatesh, Maukers Alem Lima Dias, A. Tardelli, A.J. de Abreu, V. G. Pillat, Alessio Pignalberi, M.J.A. Bolzan, B. A. Ribeiro, Francisco Vieira, Jean‐Pierre Raulin, C. M. Denardini, M.O. Arcanjo, Gopi K. Seemala