Ray tracing of auroral Z mode radiation, AKR and auroral hiss

While observed frequency bandwidths of auroral Z mode radiation cannot
be directly accounted for in terms of direct cyclotron maser instability
generation, ray tracing in a hot plasma indicates that if the radiation
near a plasma frequency lower than the gyrofrequency, the observed
bandwidths are explainable in terms of upward propagation away from the
earth. An auroral Z-mode generation mechanism is proposed involving mode
conversion from O-mode auroral kilometric radiation (AKR) at the plasma
frequency, as well as mode conversion from upgoing auroral hiss. Ray
tracings in the O mode identify a possible AKR source region along L =
8.55.