The analysis of ionospheric data taken from 54 ionosonde observatories throughout the world indicates the presence of several traveling ionospheric disturbances originating from the five high‐altitude nuclear tests conducted over Johnston Island in 1962. These disturbances were propagated over large distances and were observed as changes in the F2‐layer critical frequency. They are interpreted as a series of waves that are propagated at various velocities. Travel time curves are presented indicating dispersion and a range of velocities from 50–900 m/sec.
In a previous paper [Breitling et al, 1967] we have discussed traveling ionospheric disturbances generated by high‐altitude nuclear explosions. These disturbances were identified through the use of ƒ0F2 data from 54 ionospheric observatories ranging in distance from 3000 to 12,000 km from Johnston Island. The changes in ƒ0F2 were divided by the monthly mean ƒ0F2 values so as to indicate the change in electron number density; and those changes that exceeded ±0.30 and were subjectively abrupt were considered to be an indication of a traveling disturbance. Travel time curves were then drawn and the velocities calculated.
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