VLF propagation in the magnetosphere during sunrise and sunset hours


  • F. Walter,

  • R. R. Scarabucci


Whistlers observed on records of the OGO-4 satellite during the sunset/sunrise hours show evidence of both the proresonance (PR) and prolongitudinal (PL) mode of propagation. By tracingrays in a model magnetosphere suitable for these hours, the whistlers observed on these records are reproduced. The upper cutoff frequency presented in the walking trace whistlers appears naturally as a consequence of the inclusion of latitudinal gradients in the electron density model. A new whistler trace is predicted which appears as a consequence of the transition from the PR to the PL mode of propagation.