was a Japanese physicist specializing in the near-Earth space environment.[1] He served as Secretary General of the International Association of Geomagnetism and Aeronomy from 1975 to 1983. In 1990 he was awarded the AGU's Waldo E. Smith Award.[2]
He is best known for proving that, under certain conditions, the magnetic field from a field-aligned current and the magnetic field from the associated Pederson current in the ionosphere would exactly cancel at the surface of the Earth. The magnetic equivalence of field-aligned currents with Pederson currents is referred to colloquially as Fukushima's Theorem.[3]