@Article{SahaiBitSobFagTak:1996:ObIoPl,
author = "Sahai, Yogeshwar and Bittencourt, Jos{\'e} Augusto and Sobral,
Jos{\'e} Humberto Andrade and Fagundes, Paulo Roberto and
Takahashi, Hisao",
title = "Observations of ionospheric plasma depletions using OI 630.0 nm
nightglow imaging",
journal = "Revista Brasileira de Geof{\'{\i}}sica",
year = "1996",
volume = "14",
number = "1",
pages = "15--28",
keywords = "AERONOMIA, ionosf{\'e}ricos, bolhas de plasma, luminescencia,
deple{\c{c}}{\~a}o, emiss{\~a}o, imagens, ionospherics, olasma
bubbles, airglow, depletion, emission5images.",
abstract = "Ionospheric plasma irregularities associated with nighttime
equatorial spread-F phenomena have been tile subject of intensive
experimental and theoretical investigations during recent years.
Large scale plasma deplections, 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§S, 45.0§ W, dip latitude 15.8§ S), in March 1987.
This wide angle imaging technique provides an unique capability of
permitting 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§
S, 38.4§ W, dip latitude 3.7§ S). A VH:IF 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 paramcte7-s. In this paper we present and discuss some
features of the OI 630.0 nm emission all-sky imaging observations
carried out during the period 1987-1999. 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 tile 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 tile altitude-latitude
extent of the plasma depleted regions and some results are
presented. It has been observed that the altitudes reached by the
plasma depleted flux tubes over the magnetic equator in the
Brazilian sector often exceed 2500 km.",
issn = "0102-261X",
label = "9665",
targetfile = "8746.pdf",
urlaccessdate = "04 maio 2024"
}