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.
Study of field-aligned ionospheric E-region irregularities and sporadic E at HF
Untersuchung der unteren Ionosphaere mittels eines raketen-getragenen Riometers
Indian Journal of Radio and Space Physics ; 3 , 1 ; 70-75
1974
, 13 Quellen
Article (Journal)
English
IONOSPHAERE , ANTENNE , RAUSCHEN , ELEKTRONENDICHTE , MESSGERAET , IMPEDANZ , ABSORPTION
Ionospheric irregularities and scintillation
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