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Annales Geophysicae An interactive open-access journal of the European Geosciences Union
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Volume 29, issue 10
Ann. Geophys., 29, 1765–1778, 2011
© Author(s) 2011. This work is distributed under
the Creative Commons Attribution 3.0 License.
Ann. Geophys., 29, 1765–1778, 2011
© Author(s) 2011. This work is distributed under
the Creative Commons Attribution 3.0 License.

Regular paper 10 Oct 2011

Regular paper | 10 Oct 2011

Storm-time total electron content and its response to penetration electric fields over South America

P. M. de Siqueira1, E. R. de Paula1, M. T. A. H. Muella2, L. F. C. Rezende1, M. A. Abdu1, and W. D. Gonzalez1 P. M. de Siqueira et al.
  • 1National Institute for Space Research, INPE, Av. dos Astronautas 1758, Jardim da Granja, 12227-010, São José dos Campos-SP, Brazil
  • 2Universidade do Vale do Paraíba, UNIVAP, Laboratório de Física e Astronomia, IP&D, Av. Shishima Hifumi 2911, Urbanova, 12244-000, São José dos Campos-SP, Brazil

Abstract. In this work the response of the ionosphere due to the severe magnetic storm of 7–10 November 2004 is investigated by analyzing GPS Total Electron Content (TEC) maps constructed for the South America sector. In order to verify the disturbed zonal electric fields in South America during the superstorm, ionospheric vertical drift data obtained from modeling results are used in the analysis. The vertical drifts were inferred from ΔH magnetometer data (Jicamarca-Piura) following the methodology presented by Anderson et al. (2004). Also used were vertical drifts measured by the Jicamarca ISR. Data from a digisonde located at São Luís, Brazil (2.33° S, 44.2° W, dip latitude 0.25°) are presented to complement the Jicamarca equatorial data. Penetration electric fields were observed by the comparison between the equatorial vertical drifts and the Interplanetary Electric Field (IEF). The TEC maps obtained from GPS data reflect the ionospheric response over the South America low-latitude and equatorial region. They reveal unexpected plasma distributions and TEC levels during the main phase of the superstorm on 7 November, which is coincident with the local post-sunset hours. At this time an increase in the pre-reversal enhancement was expected to develop the Equatorial Ionization Anomaly (EIA) but we observed the absence of EIA. The results also reveal well known characteristics of the plasma distributions on 8, 9, and 10 November. The emphasized features are the expansion and intensification of EIA due to prompt penetration electric fields on 9 November and the inhibition of EIA during post-sunset hours on 7, 8, and 10 November. One important result is that the TEC maps provided a bi-dimensional view of the ionospheric changes offering a spatial description of the electrodynamics involved, which is an advantage over TEC measured by isolated GPS receivers.

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