Laundal, K. M., C.C. Finlay, N. Olsen, J.P. Reistad, P. Tenfjord, N. Østgaard, A. Ohma, K. Snekvik, S.E. Haaland, and S.E. Milan, Characterizing external influence on the large-scale polar ionospheric current system, IAGA assembly, Cape Town, South Africa, August 2017 (Invited talk)