Equatorial Irregularity Campaigns. Part I. Correlated Scintillation and Radar Backscatter Measurements in October 1976.

摘要

An intensive study of nighttime electron density irregularities in the equatorial ionosphere was conducted in October 1976 by making simultaneous radar and scintillation measurements near the magnetic dip equator. The 50-MHz radar observations at Jicamarca, Peru, and scintillation measurements at nearby ground stations of Ancon and Huancayo, Peru, were made by receiving VHF transmissions from the geostationary satellites, LES-9 and Marisat, as well as the VHF transmissions from the orbiting Wideband satellite. The thick irregularity patches detected by the radar could be associated with intense scintillation events, signifying thereby that the patches containing 3-m irregularities also contain kilometer-sized irregularities, giving rise to the radar backscatter and scintillations, respectively. By comparison of the onset times of scintillation on different propagation paths separated in the east-west direction, as well as by performance of spaced receiver scintillation measurements at Ancon, the drift speed of irregularities was determined. The irregularities were observed to drift eastwards at a speed ranging between 90 and 140 m per sec during 1900 and 2400 local time. From a knowledge of the derived value of drift speed and the duration of scintillation events, the irregularity patches were found to have eastward dimensions between 100 and 800 kilometers. On a statistical basis, the irregularity patches detected in the scintillation experiment were noted to be preponderant to those giving rise to thick radar backscatter structures. This indicates the possiblity of having equatorial irregularity patches with spectral powers concentrated at large scale sizes only. (Author)