Produção Nacional
Investigation of OI 557.7 nm and OI 630.0 nm nightglow intensity ratios during the occurrence of equatorial F-region plasma bubbles
1995; Elsevier BV; Volume: 57; Issue: 8 Linguagem: Inglês
10.1016/0021-9169(94)00064-u
ISSN1878-593X
AutoresP. R. Fagundes, Y. Sahai, H. Takahashi,
Tópico(s)GNSS positioning and interference
ResumoAbstract It is well-known that, at equatorial and low-latitudes, the OI 557.7 nm emission emanates both from the mesosphere and F-region. Earlier investigations using, in general, ground-based simultaneous observations indicate that the contribution to the OI 557.7 nm emission from the F-region is about 20% of the F-region OI 630.0 nm emission. Both of these emissions are excited by the dissociative recombination process (O 2 + + e → O ∗ ( 1 S, 1 D) + O) in the F-region. The nocturnal intensity variations of these emissions sometimes show large short-lived depletions, associated with the passage of equatorial spread-F plasma bubbles through the field of view of a photometer. Regular observations of these emissions have been carried out at Cachoeira Paulista (22.7°S, 45.0°W), Brazil, since 1973. In this paper, we present and discuss simultaneous observations of these emissions, during periods of strong equatorial spread-F conditions, when both emissions show large intensity drop-outs. Twenty-five nights of measurements from Cachoeira Paulista have been analysed for this study, which indicate that the average ratio of the intensity depletions ( ΔI557.7 nm ΔI630 nm ) is about 0.26±0.07 for F-region altitudes, and this component has a dependence on the height of the electron density profile.
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