Ionospheric scintillations at 136 MHz from a synchronous satellite

Abstract

Scintillation observations at 136MHz were made using the Early Bird synchronous satellite during the summer of 1965 from two middle latitude sites. The diurnal pattern of the scintillations had the following characteristics: 1. a. Two maxima were found, one near midday, the other near midnight. 2. b. The patch of irregularities which produced the midday scintillation moved through the antenna beam in a few minutes to 14 min. 3. c. The midday scintillations had a high probability of occurrence when ƒ 0E 8 ≥ 5 MHz . 4. d. The scintillations observed from 1900 to 0300 local time were of long duration (greater than 30 min) 5. e. The start and stop time of night scintillations were well correlated at Greenbank, West Virginia and Sagamore Hill, Massachusetts, a separation of subionospheric latitude of approximately 4 degrees. 6. f. 48 per cent of the nighttime scintillations were accompanied by spread F; 25 per cent of the night hours showed spread F. 7. g. The period of the scintillation (peak to peak time of the individual fluctuation) ranged predominantly from 5 sec to 1 min. 8. The picture that evolves is that summer daytime scintillations during periods of low magnetic activity are probably associated with sporadic- E patches of 300–600 km with high critical frequency sporadic- E. Nighttime scintillation is correlated with spread F, geomagnetieally controlled and occurs over a large latitude range in the same time zone.