Terrestrial continuum radiation observations with GEOS‐1 and ISEE‐1

Examples of results from a dual satellite (GEOS‐1 and ISEE‐1) study of terrestrial non‐thermal electromagnetic continuum radiation are presented. The problems of sources and generation mechanisms are discussed in the context of simultaneous measurements of radiation arrival directions, radiation cut‐offs, and detailed spectral observations. The results, which imply significant contributions from the magnetospheric volume to the low frequency (‘trapped’) component, confirm the near‐plasmapause as the source of the higher frequency (‘escaping’) component. The detection of significant X mode radiation and the implied presence of localized non‐directive sources lead us to conclude that current theories of generation are inadequate.