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.
During 29 crossings of the geomagnetic dip equator near 80°W longitude in February and July 1964, airborne equipment obtained cross sections of geomagnetic field intensity and ionospheric characteristics. The magnetic anomalies due to the electrojet and the amplitudes of Esq echoes show fair correlation of details and fair‐to‐good correlation of large scale features. Width and position of the electrojet vary considerably from hour to hour and from day to day. The data suggest that the electrojet during certain days in February was separated into two or more parallel streaks. The magnetic data also show strong electric currents in the ocean. Those appear to be a sector of the ‘internal part’ of the Sq current system, however stronger than anticipated.
The propagation of I-IF radio waves along field-aligned ionization gradients along geomagnetic shells L ----3.5 and L ----1.6 was investigated with airborne equipment at the southern conjugate points. Both pulse travel time and Doppler shift techniques were employed to detect these magnetospheric signals and to differentiate them from signals propagated via the ionosphere. By means of the Doppler shift technique, a signal component was detected that had the frequency shift predicted for magnetospheric propagation. This signal was estimated to have a transmission loss considerably greater than that for ionospheric propagation. duced by the aircraft crew under the technical supervision of R. Gowell of AFCRL and with Major R. Creager of the 3245th Air Base Group as aircraft commander. We thank R. Miner of AFCRL for additional ionospheric data and E. Maple for the use of an ELF spectrum analyzer. Worldwide Broadcasting, Scituate, Massachusetts, kindly furnished us data on the transmitters and antennas. The transmissions from California were arranged by R. Eshleman of the Radio Science Laboratory of Stanford University. Radio station LOL in Buenos Aires, Argentina, was very cooperative in sending us timing signals after normal shut down. M. Morgan and T. Laaspere of Dartmouth College helped with stimulating discussions.
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