A full-wave study of downward propagating ELF waves in the ionosphere: Ion cutoff whistlers and the low frequency cutoff of ELF noise

摘要: Abstract The downward propagation of ELF waves (100–700 Hz) in the ionosphere is studied by means a generalised multiple-reflection full-wave method. It shown that for production an ion cutoff whistler incident wave-normal must point inwards (equatorwards) with respect to vertical, conversion coefficient RRL being maximum when reflected wave normal lies close geomagnetic field direction at crossover level. For low frequency noise exist, wave-normals level lie outside ‘cone penetration’ ~40° semi-vertical angle, whose axis coincides line. magnetic meridian plane, total reflection downgoing whistlers obtained either large outward (poleward) angles, heights generally above and possibly even gyrofrequency level, or else inward (equatorward) directions, which case process usually occurs below involves R L mode on path. Analysis scatter plot lower frequencies as function altitude latitude shows widely varying abundances be postulated all latitudes order explain observations.