A continuous series of oblique backscatter observations at 19 MHz made at Plum Island, Massachusetts, (56 N invariant) over nearly half a solar cycle is utilized to derive the occurrence characteristics of aspect sensitive field-aligned irregularities in the E-layer and their association with ground backscattered echoes which are propagated via sporadic E(Es) reflection. Under quiet magnetic conditions, it is found that the field-aligned echo from E-layer heights (FAE(E)) displays a summer evening maximum in conjunction with the Es echo. A weak secondary maximum is observed in the winter with no detectable field-aligned structures being evident in the day-time Es. During disturbed magnetic conditions, the Es ground back-scattered echo is greatly suppressed together with a simultaneous increase of the FAE(E) which also appear in the day-time; no seasonal control is evident. These observations are discussed from the point of view of current plasma instability theories.


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    Title :

    Study of field-aligned ionospheric E-region irregularities and sporadic E at HF


    Additional title:

    Untersuchung der unteren Ionosphaere mittels eines raketen-getragenen Riometers


    Contributors:
    Basu, S. (author) / Vesprini, R.L. (author) / Aarons, J. (author)

    Published in:

    Publication date :

    1974


    Size :

    , 13 Quellen


    Type of media :

    Article (Journal)


    Type of material :

    Print


    Language :

    English