@Article{KlausnerFaSaWrPiBe:2009:ObGWOs,
author = "Klausner, Virginia and Fagundes, Paulo Roberto and Sahai,
Yogeshwar and Wrasse, Cristiano M. and Pillat, Valdir Gil and
Becker-Guedes, F.",
affiliation = "{Universidade do Vale do Para{\'{\i}}ba (UniVap)} and
{Universidade do Vale do Para{\'{\i}}ba (UniVap)} and {Instituto
Nacional de Pesquisas Espaciais (INPE)} and {Universidade do Vale
do Para{\'{\i}}ba (UniVap)} and {Universidade do Vale do
Para{\'{\i}}ba (UniVap)} and {Universidade do Vale do
Para{\'{\i}}ba (UniVap)}",
title = "Observations of GW/TID oscillations in the F2 layer at low
latitude during high and low solar activity, geomagnetic quiet and
disturbed periods",
journal = "Journal of Geophysical Research",
year = "2009",
volume = "114",
number = "A02313",
month = "Feb.",
keywords = "gravity-wave activity, ionosphere, equatorial, events, region,
terminator, Brazil.",
abstract = "Ionospheric vertical sounding observations, using a digital
ionosonde, are being carried out on a routine basis at Sao Jose
dos Campos (23.2 degrees S, 45.9 degrees W; dip latitude 17.6
degrees S, hereafter referred to as SJC), Brazil, located under
the southern crest of the equatorial ionization anomaly (EIA),
since August 2000. In this paper, we present and discuss the
seasonal variation of gravity wave (GW) and traveling ionospheric
disturbance (TID) oscillations in the ionospheric F2 layer during
high solar activity (HSA, September 2000 to August 2001) and low
solar activity (LSA, January 2006 to December 2006) observed at
SJC during different levels of geomagnetic activity. The GW/TID
signatures in the F2 layer can be seen in the isofrequency lines
of virtual height daily variations for six fixed frequencies (3,
4, 5, 6, 7, and 8 MHz) which show quasiperiodic oscillations
(crests and valleys). The crests and valleys when seen in close
frequencies present a phase difference (i.e., first it is observed
at higher frequency then at lower frequency), indicating a
downward phase velocity. These quasiperiodic oscillations induced
in the virtual heights are divided into three groups as small
amplitude (lower than 40 km), medium amplitude (between 40 km and
60 km), and large amplitude (greater than 60 km). The observations
show that GWs/TIDs are much more pronounced at F layer heights
during HSA than LSA and the large-amplitude GWs/TIDs are present
normally only during HSA.",
doi = "10.1029/2008JA013448",
url = "http://dx.doi.org/10.1029/2008JA013448",
issn = "0148-0227 and 2156-2202",
language = "en",
targetfile = "jgra19531.pdf",
urlaccessdate = "16 jun. 2024"
}