Location of generation regions (inLand λ) of midlatitude VLF discrete emissions by dispersion analysis of ground station observations

Dispersion analysis of emission echoes, triggering whistlers, and associated whistlers determines the minimum gyrofrequency (and hence L shell) and the plasma density along the path for each event. These measurements and comparison with the plasmapause −Kp relationship indicate that midlatitude emissions are generated and propagate near the plasmapause, usually just inside the plasmasphere. Evidence for generation at or about the equatorial plane is that the dynamic spectrum of hook emissions is closely symmetrical about minimum frequency if the appropriate amount of path dispersion to the observer (½ or 1½ hop) is subtracted.