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Titre du Document
Forecasting the occurrence of ionospheric scintillation activity in the equatorial ionosphere on a day-to-day basis
In the low-latitude ionospheric F region, ambient conditions after sunset are often conducive to the generation of small-scale plasma density structures by the Rayleigh-Taylor instability mechanism. Radio wave signals passing through these electron density irregularities experience amplitude fluctuations that lead to radio wave scintillation. The scintillation index, S4, is a measure of the severity of these amplitude fluctuations. It is well known that the occurrence frequency of scintillation activity depends on solar cycle, season, longitude and local time, with a large day-to-day variability. In this paper, we present the results of a continuing study that utilizes a ground-based digital sounder at the magnetic equator to provide a forecast of the subsequent occurrence of scintillation activity and a network of UHF and L-band receivers that measure the S4 index, on a night-to-night basis. To establish the forecasting relationship, observations were carried out in 1998 and 1999 in the Peruvian/Chilean longitude sector. The relationship between the magnitude of the vertical E x B drift velocity enhancement just after sunset as determined by the Jicamarca Digisonde and the magnitude of the S4 index subsequently observed an hour or two later by the scintillation receivers at Ancon, Peru and Antofagasta, Chile was established. In most cases at both UHF and L-band frequencies, this relationship is not linear, but there appears to be a threshold in E x B drift of ∼ 20 m/s. On
Type du document
Conférence : 40th Years of Equatorial Aeronomy Sparked by the Jicamarca Radio Observatory. Workshop, Lima, PER, 2002-05
ISSN : 1364-6826
Journal of atmospheric and solar-terrestrial physics A. 2004, vol. 66, n° 17, pp. 1567-1572 [6 pages] [bibl. : 7 ref.]
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