Possible Relation of a Specific Ionospheric Event to Simultaneous Meteorological Data

Abstract

DURING the night of October 31/November 1, 1967, a sudden change in the structure of amplitude scintillations of radio signals from the S-66 BEC satellite was observed at Fort Monmouth. Observations made at 41, 40 and 20 MHz are indicated in Fig. 1, which relates to orbit 12239; the satellite was passing in a west–east direction near 40° N latitude. The unusual event was manifested by (1) a train of strong and frequent amplitude scintillations which was interrupted for a short period and resumed 60 s later and by (2) a similar interruption showing also a scintillation-free zone during 44 s of the following orbit, 12240. The polarization of the signals displayed corresponding variations. Usually such short and sudden interruptions of strong amplitude scintillations are not observed with satellite signals. The geographic location of the subionospheric tracks from 350 km altitude of these two passages is shown by the dashed lines in Fig. 2. The start and end of the scintillation-free intervals, as obtained from amplitude recordings, are given in Table 1. The related total integrated electron content was obtained from measurements of a polarization follower having sampling times of 80 µs and automatic digitized printout for each time second. The electron content curves show a familiar oscillatory pattern¹ which characterizes the observation of severe amplitude scintillations. During the “no-scintillations” periods shown in Table 1, the electron content followed a smooth curve.