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美国政府科技报告
>SUDDEN IONOSPHERIC DISTURBANCES AND THE PROPAGATION OF VERY-LOW-FREQUENCY RADIO WAVES Part Ⅰ: Phenomenology and Relevant Ionospheric Theory
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SUDDEN IONOSPHERIC DISTURBANCES AND THE PROPAGATION OF VERY-LOW-FREQUENCY RADIO WAVES Part Ⅰ: Phenomenology and Relevant Ionospheric Theory
The changes in VLF radio noise accompanying a solar flare and its asso¬ciated sudden ionospheric disturbance (SID) are surveyed. The onset time of the effects is about 10 minutes, but may be less than 2 minutes for perhaps 5 per¬cent of the incidents. The alteration in propagation conditions implies an in¬crease in noise on frequencies exceeding 20 kc and a decrease below 10 kc. If a local thunderstorm develops, the time phasing is very similar to that of an SID incident, but noise at all frequencies is enhanced.nA detailed examination of the formative processes of the lower ionosphere is made. Values of the rate coefficients for attachment, detachment (photo, collisional, and associative), electron-ion recombination, and ion-ion recom¬bination, are deduced for heights from 40 to 100 km.
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