Articles | Volume 22, issue 9
Ann. Geophys., 22, 3211–3219, 2004
https://doi.org/10.5194/angeo-22-3211-2004

Special issue: Equatorial and low latitude aeronomy (ELLA)

Ann. Geophys., 22, 3211–3219, 2004
https://doi.org/10.5194/angeo-22-3211-2004

  23 Sep 2004

23 Sep 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 W. L. C. Lima et al.
  • 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.