@Article{SahaiBitSobFagTak:1996:ObIoPl,
author = "Sahai, Yogeshwar and Bittencourt, Jose Agusto and Sobral, Jose
Humberto Andrade and Fagundes, Paulo Roberto and Takahashi,
Hisao",
title = "Observations of ionospheric plasma depletions using OI 630.0 nm
nightglow imaging",
journal = "Revista de la Academia de Ciencias de Bolivia",
year = "1996",
volume = "14",
number = "1",
pages = "15--28",
keywords = "AERONOMIA, MONOSFERA, BOLHAS DE PLASMA, DEPLECOES DE PLASMA,
LUMINESCENCIA, IMAGEAMENTO OTICO, EMISSAO OI 630.0 NM.",
abstract = "Ionospheric plasma irregularities associated with nighttime
equatorial spread-F phenomena have been the subject of intensive
experimental and theoretical investigations during recent years.
Large scale plasma depletions, referred to as transequatorial
bubbles or plumes, continue to attract considerable attention. The
studies of ionosphere plasma irregularities assume great
importance, because the irregularities degrade the radio wave
signals passing through the region and, therefore, have
considerable influence on the ionospheric/trans-ionospheric radio
wave communications. The F-region nightglow emissions arising from
ionospheric recombination processes can be used to remotely
observe the dynamics of transequatorial ionospheric plasma bubbles
and smaller scale plasma irregularities. In a collaborative
project between the Center for Space Physics, Boston University,
USA- and the National Institute for Space Research (INPE), Brazil,
an all-sky imaging system was put in operation at Cachoeira
Paulista (22.7 degree S, 45.0 degree W, dip latitude 15.8 degree
S), in March 1987. This wide angle imaging technique provides an
unique capability of permiting observations over regions covering
several million square kilometers from a single observing station.
Also, regular measurements of several nightglow emissions and
ionospheric sounding are carried out at Cachoeira Paulista and
Fortaleza (3.9 degree S, 38.4 degree W, dip latitude 3.7 degree
S). A VHF electronic polarimeter was in operation at Cachoeira
Paulista. This clustering of observational facilities in the
Brazilian sector provided coincident and complementary
observations of various upper atmospheric parameters. In this
paper we present and discuss some features of the 01630.0 nm
emission all-sky imaging observations carried out during the
period 1987-1989. The transequatorial ionospheric plasma bubbles
manifest in all-sky optical imaging observations as nearly
north-south aligned intensity-depleted regions. The observed
seasonal variation of the airglow depletions shows a maximum
during the summer months and virtually no airglow depletions
during the winter months. The case studies presented show
different forms of generation and development phases of airglow
depletions during the course of a night. The all-sky images also
permitted the determination of the altitude-latitude extent of the
plasma depleted regions and some results are presented. It has
been observed that the attitudes reached by the plasma depleted
flux tubes over the magnetic equator in the Brazilian sector-often
exceed 2500 km.",
label = "8766",
targetfile = "7406.pdf",
urlaccessdate = "05 maio 2024"
}