Letter | Published:

Topside Ionospheric Structure at Northern Mid-latitudes after Ground Sunset in Summer

Nature volume 222, pages 11551156 (21 June 1969) | Download Citation



DURING the period between ground sunset and ionospheric sunset, the solar light is considerably filtered during its passage through the entire atmosphere before reaching still-illuminated ionospheric regions. Most of the ionizing radiation is absorbed before it reaches the illuminated regions, hence only some heating might be caused by the long-wavelength spectrum of the incident radiation. It seems reasonable, however, to expect that topside regions are thermally stable because they have been illuminated for a long period of time.

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  1. 1.

    , and , Nature, 220, 459 (1968).

  2. 2.

    , , and , Quick-Look System for Virtual Real Time Reception of Topside Ionograms, Special Issue Proc. IEEE on Topside Sounding (in the press).

  3. 3.

    , Radio Sci., 1, 1158 (1966).

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  1. Institute for Exploratory Research, US Army Electronics Command, Fort Monmouth, New Jersey.

    • P. R. ARENDT
    •  & H. SOICHER


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