Radio echoes from field-aligned ionization above the magnetic equator and their resemblance to auroral echoes

Abstract

During the International Geophysical Year, under the joint auspices of the United States National Committee for the IGY, the Voice of America, and the National Bureau of Standards, we operated a chain of 50 Mc/s VHF forward scatter circuits near the magnetic equator in South America [Bowles and Cohen, 1957]. An intense mode of VHF propagation associated with equatorial sporadic E was found to occur and was demonstrated to be closely identifiable in time-variation and height with the equatorial electrojet. (A brief account of these findings was published by Gates [1959] and a more comprehensive report will be submitted shortly for publication.) As a result of Stanford University IGY backscatter studies at Huancayo, Egan (Stanford University Radio Propagation Laboratory Tech. Rept. 1, December 30, 1959, unpublished) confirmed our expectation [Bowles and Cohen, 1957] that the radio echoes from irregularities in the vicinity of the equatorial E region exhibit a magnetic-field related aspect sensitivity similar to that of radio echoes from auroral ionization.