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Ann. Geophys., 22, 3211-3219, 2004
www.ann-geophys.net/22/3211/2004/
© European Geosciences Union 2004
Response of the equatorial and low-latitude ionosphere during the space weather events of April 2002
W. L. C. Lima1, F. Becker-Guedes2, Y. Sahai2, P. R. Fagundes2, J. R. Abalde2, G. Crowley3, and J. A. Bittencourt4
1Centro Univ. Luterano de Palmas (CEULP), Universidade Luterana do Brasil (ULBRA), 77054-970 Palmas, TO, Brazil
2Universidade do Vale do Paraíba (UNIVAP), 12244-000 São José dos Campos, SP, Brazil
3Southwest Research Institute, San Antonio, TX 78238-5166, USA
4Instituto Nacional de Pesquisas Espaciais (INPE), 12201-970 São José dos Campos, SP, Brazil
Abstract. A digital ionosonde, of the type known as Canadian Advanced Digital
Ionosonde (CADI), has been in routine operation at São José dos
Campos (23.2° S, 45.9° W; dip latitude 17.6° S), Brazil, since
August 2000. A new CADI was installed at Palmas (10.2° S, 48.2° W;
dip latitude 5.5° S), Brazil, in April 2002. The two CADIs are part of a
new network being established in a collaborative program between UNIVAP and
CEULP/ULBRA, to study the equatorial and low-latitude ionospheric regions in
Brazil. In this paper we present and discuss the effects of the space
weather events during 17-20 April 2002, as evidenced by the ionospheric
parameter changes from simultaneous observations at São José dos
Campos and Palmas. A comparison of the observed ionospheric parameters (h'F,
hpF2 and foF2) at the two stations, separated only by about 1460km, shows
both similarities and differences associated with the geomagnetic
disturbances. Also, a comparison of the observed F-region parameters with
the ASPEN-TIMEGCM model results is presented. The model results show
reasonable agreement during the quiet period of observations, but some
discrepancies have been observed during the geomagnetic disturbances.
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