@Article{BatistaAbSoBeMaCaBa:2006:UnEaMo,
author = "Batista, Inez Staciarini and Abdu, Mangalathayil Ali and Souza,
Jonas Rodrigues and Bertoni, Fernando Celso Perin and Matsuoka, M.
T. and Camargo, P. O. and Bailey, G. J.",
affiliation = "Instituto Nacional de Pesquisas Espaciais, Divis{\~a}o de
Aeronomia (INPE.DAE) and Instituto Nacional de Pesquisas
Espaciais, Divis{\~a}o de Aeronomia (INPE.DAE) and Instituto
Nacional de Pesquisas Espaciais, Divis{\~a}o de Aeronomia
(INPE.DAE) and Instituto Nacional de Pesquisas Espaciais,
Divis{\~a}o de Aeronomia (INPE.DAE) and {Universidade Estadual
Paulista} and {Universidade Estadual Paulista} and {University of
Sheffield}",
title = "Unusual early morning development of the equatorial anomaly in the
Brazilian sector during the Halloween magnetic storm",
journal = "Journal of Geophysical Research",
year = "2006",
volume = "111",
number = "A5",
pages = "A05307 (10pp)",
month = "May",
keywords = "low latitudes, electric-field, ionosphere, region, model,
satellite, radar, drif.",
abstract = "The solar events that occurred at the end of October 2003 gave
rise to very strong geomagnetic disturbances that peaked twice
with Dst values reaching -345 nT around 0000 UT on 30 October and
-400 nT around 2300 UT, on the same day. Disturbances in several
ionospheric parameters were observed over Brazil. This work will
focus on the ionospheric response to the initial westward prompt
penetration electric field and on the strong intensification of
the equatorial ionization anomaly that occurred because of the
electric field polarity reversal that followed in the early
morning hours of 29 October. The F layer peak height over the
equator first decreased under the strong prompt penetration
westward electric field, which was followed by significant height
increase under eastward electric field. We have used Sheffield
University Plasmasphere Ionosphere Model (SUPIM) with an
intensified westward disturbed electric field in the presunrise
hours, presumably due to prompt penetration from the
magnetosphere, in order to study the effect of such a field in the
ionosphere. The simulation results showed that prompt penetration
of magnetospheric electric fields of westward polarity to the
nightside equatorial region seems to be the most probable cause of
the initial F layer height decreases. The intensification of the
equatorial ionization anomaly and the unusual enhancement on F
layer peak density, which was not modeled by the SUPIM, are
explained as caused by the strong eastward electric field that
followed the initial phase in combination with a highly variable
disturbed meridional/transequatorial wind system as inferred from
the F2 layer peak height variations. The highly dynamic wind
pattern, with a short-term response (2-4 hours), is compatible
with the predictions of some previous theoretical model
calculations reported in the literature.",
doi = "10.1029/2005JA011428",
url = "http://dx.doi.org/10.1029/2005JA011428",
issn = "0148-0227 and 2156-2202",
language = "en",
targetfile = "jgra18183.pdf",
urlaccessdate = "16 jun. 2024"
}