Vertical Ionospheric Sounding Measurements

This report presents data on the ionospheric perturbations resulting from the five 1962 highaltitude nuclear detonations, Star Fish, Check Mate, Blue Gill, King Fish, and Tight Rope, as obtained with sweep-frequency vertical- incidence ionosondes operated at the Islands of Maui, Tern French Frigate Shoals, Midway, Wake Star Fish only, Canton, Tutuila American Samoa, and Tongatapu. The ionosondes at Midway and Tongataupu had a frequency range of 1 to 25 mc. At the other stations the range was 0.25 to 20 mc. The objective was to obtain information on the immediate and delayed effects on the ionosphere, including radio wave absorption and changes in electron density, at various distances and directions from the detonations. Beginning a few minutes before detonation, each ionosonde was operated continuously until about H 2 hoours, when the interval between ionograms was increased to five minutes for several more hours. Otherwise, ionograms were made at 15-minute intervals.