Rocket observations of low-latitude whistlers and their propagation characteristics in the magnetosphere and ionosphere

Ground whistlers suffer the ionospheric screening effect, which weakens their intensity. Further, it is quite difficult to find their path latitude. It has been necessary to make VLF observations in the ionosphere and magnetosphere in addition to ground-based measurements. The authors and colleagues have carried out rocket observations of VLF phenomena including whistlers and plasma waves since 1963, and this paper summarizes the whistler data. The important results are the evidence of the presence of low-latitude whistler ducts and data on their properties. Further, in this paper the ionospheric screening effect on whistlers and the propagation characteristics of whistlers in the ionosphere are discussed based on simultaneous observations on rockets and on the ground.