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Unusual nighttime impulsive foF2 enhancements at low latitudes: Phenomenology and possible explanations
Author(s)
Language
English
Obiettivo Specifico
2A. Fisica dell'alta atmosfera
1IT. Reti di monitoraggio e Osservazioni
4IT. Banche dati
Status
Published
JCR Journal
JCR Journal
Peer review journal
Yes
Title of the book
Issue/vol(year)
3/54(2014)
ISSN
0273-1177
Electronic ISSN
1879-1948
Publisher
Elsevier Science Limited
Pages (printed)
369-384
Issued date
August 1, 2014
Subjects
Abstract
This paper is focused on unusual nighttime impulsive electron density enhancements that are rarely observed at low latitudes on a
wide region of South America, under quiet and medium/high geomagnetic conditions. The phenomenon under investigation is very peculiar because besides being of brief duration, it is characterized by a pronounced compression of the ionosphere. The phenomenon was studied and analyzed using both the F2 layer critical frequency (foF2) and the virtual height of the base of the F region (h'F) values recorded at five ionospheric stations widely distributed in space, namely: Jicamarca (-12.0°, -76.8°, magnetic latitude -2.0°), Peru; Sao Luis (-2.6°, -44.2°, magnetic latitude +6.2°), Cachoeira Paulista (-22.4°, -44.6°, magnetic latitude -13.4°), and Sao Jose´ dos Campos (-23.2°, -45.9°, magnetic latitude -14.1°), Brazil; Tucumán (-26.9°, -65.4°, magnetic latitude -16.8°), Argentina. In a more
restricted region over Tucumán, the phenomenon was also investigated by the total electron content (TEC) maps computed by using measurements from 12 GPS receivers. A detailed analysis of isoheight ionosonde plots suggests that traveling ionospheric disturbances (TIDs) caused by gravity wave (GW) propagation could play a significant role in causing the phenomenon both for quiet and for medium/high geomagnetic activity; in the latter case however a recharging of the fountain effect, due to electric fields penetrating from the
magnetosphere, joins the TID propagation and plays an as much significant role in causing impulsive electron density enhancements.
wide region of South America, under quiet and medium/high geomagnetic conditions. The phenomenon under investigation is very peculiar because besides being of brief duration, it is characterized by a pronounced compression of the ionosphere. The phenomenon was studied and analyzed using both the F2 layer critical frequency (foF2) and the virtual height of the base of the F region (h'F) values recorded at five ionospheric stations widely distributed in space, namely: Jicamarca (-12.0°, -76.8°, magnetic latitude -2.0°), Peru; Sao Luis (-2.6°, -44.2°, magnetic latitude +6.2°), Cachoeira Paulista (-22.4°, -44.6°, magnetic latitude -13.4°), and Sao Jose´ dos Campos (-23.2°, -45.9°, magnetic latitude -14.1°), Brazil; Tucumán (-26.9°, -65.4°, magnetic latitude -16.8°), Argentina. In a more
restricted region over Tucumán, the phenomenon was also investigated by the total electron content (TEC) maps computed by using measurements from 12 GPS receivers. A detailed analysis of isoheight ionosonde plots suggests that traveling ionospheric disturbances (TIDs) caused by gravity wave (GW) propagation could play a significant role in causing the phenomenon both for quiet and for medium/high geomagnetic activity; in the latter case however a recharging of the fountain effect, due to electric fields penetrating from the
magnetosphere, joins the TID propagation and plays an as much significant role in causing impulsive electron density enhancements.
Type
article
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2014_AdvancesSpaceResearch_foF2_unusual_enhancements.pdf
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Format
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