K. Hosokawa, T. Tsugawa, K. Shiokawa, Y. Otsuka, N. Nishitani, T. Ogawa, and M. R. Hairston. Dynamic temporal evolution of polar cap tongue of ionization during magnetic storm. J. Geophys. Res., volume 115, 2010 . K. Hosokawa, T. Tsugawa, K. Shiokawa, Y. Otsuka, T. Ogawa, and M. R. Hairston. Unusually elongated, bright airglow plume in the polar cap F region: Is it a tongue of ionization? Geophys. Res. Lett., volume 36, issue 7, 2009 .