T. Nishiyama, T. Sakanoi, Y. Miyoshi, R. Kataoka, D. L. Hampton, Y. Katoh, K. Asamura, and S. Okano. Fine scale structures of pulsating auroras in the early recovery phase of substorm using ground-based EMCCD camera. J. Geophys. Res., volume 117, 2012 .