Satellite and ground observations of magnetospheric VLF hiss associated with the severe magnetic storm on May 25-27, 1967

The purpose of this paper is to make clear the characteristics of magnetospheric VLF hiss during storm times. The study is based on the VLF observations on board the Ariel 3 satellite as well as on the ground during the severe magnetic storm of May 25–27, 1967. Soon after the onset of the main phase there appeared the VLF hiss in the morning sector of the magnetosphere (‘morning hiss’) on the satellite as well as ground records, but the hiss is not observed in the evening sector. It was not until during the recovery phase that we could recognize the stationary occurrence of strong VLF hiss in the evening side of the magnetosphere (‘evening hiss’). The important features of the morning and evening hiss are described, and some discussions concerning their generation mechanism by the ring current particles are given.