Abstract Measurements in the lower ionosphere with the EISCAT UHF incoherent scatter radar at times reveal more than one maximum in the altitude profile of electron density. The uppermost of these corresponds to the normal particle E layer produced by auroral electrons. For the special cases discussed here, a second maximum at D-region heights is observed below the E-layer peak, separated from it by a distinct density minimum. Typical durations of these events are a few minutes to a few tens of minutes, and in some examples the maximum electron density in the lower layer is as large as that in the upper layer. We describe the morphology of these D-region layers, and discuss possible mechanisms of formation. It is shown that the lower layer is unlikely to be a direct product of charged particle precipitation, but that ambient metallic atoms and ions may be an important factor in the development of the layers.
Discrete layers of D-region ionisation in the high-latitude ionosphere
Advances in Space Research ; 10 , 10 ; 41-44
01.01.1990
4 pages
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
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