Short-Period Variations in the Ionosphere

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DURING the years 1938 and 1939 fixed-frequency pulse observations were being used to record continuously the virtual height and echo intensity of reflexions from the F-region at two frequencies close to the vertical penetration frequency for the region. It was noticed that, in the daytime, the penetration frequency often showed quasi-periodic fluctuations with periods of the order of half an hour. The magnitude of the fluctuation was variable but frequently of the order of 1 Mc./s. from maximum to minimum.


  1. 1

    Nature, 162, 886 (1948).

  2. 2

    Proc. Inst. Rod. Eng. (Nov. 1947).

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MUNRO, G. Short-Period Variations in the Ionosphere. Nature 163, 812–814 (1949) doi:10.1038/163812a0

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