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Volume 25, issue 4
Ann. Geophys., 25, 863–873, 2007
https://doi.org/10.5194/angeo-25-863-2007
© Author(s) 2007. This work is distributed under
the Creative Commons Attribution 3.0 License.
Ann. Geophys., 25, 863–873, 2007
https://doi.org/10.5194/angeo-25-863-2007
© Author(s) 2007. This work is distributed under
the Creative Commons Attribution 3.0 License.

  08 May 2007

08 May 2007

The ionospheric response in the Brazilian sector during the super geomagnetic storm on 20 November 2003

F. Becker-Guedes1, Y. Sahai1, P. R. Fagundes1, E. S. Espinoza2, V. G. Pillat1, W. L. C. Lima3, Su. Basu4, Sa. Basu5, Y. Otsuka6, K. Shiokawa6, E. M. MacKenzie7, X. Pi8, and J. A. Bittencourt9 F. Becker-Guedes et al.
  • 1Universidade do Vale do Paraiba (UNIVAP), São José dos Campos, SP, Brazil
  • 2Radio Observatorio de Jicamarca, Instituto Geofisico del Peru, Lima, Peru
  • 3Centro Univ. Luterano de Palmas (CEULP), Universidade Luterana do Brasil (ULBRA), Palmas, TO, Brazil
  • 4Center for Space Physics, Boston University, Boston, MA, USA
  • 5Space Vehicles Directorate, Air Force Research Laboratory, Hanscom AF Base, MA, USA
  • 6STELAB, Nagoya University, Toyokawa, Japan
  • 7Institute for Scientific Research, Boston College, Chestnut Hill, MA, USA
  • 8Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
  • 9Instituto Nacional de Pesquisas Espaciais (INPE), São José dos Campos, SP, Brazil

Abstract. A very intense geomagnetic storm (superstorm) began with storm sudden commencement (SSC) at 08:03 UT on 20 November 2003, as a result of the coronal mass ejection (CME) by sunspot 484 hurled into space on 18 November 2003. The geomagnetic storm attained |Dst|max=472 nT at 20:00 UT (20 November). In this paper we present the simultaneous ionospheric sounding observations, using the Canadian Advanced Digital Ionosondes (CADIs), carried out from Palmas (PAL; 10.2° S, 48.2° W; dip latitude 5.5° S; a near equatorial station) and São José dos Campos (SJC; 23.2° S, 45.9° W; dip latitude 17.6° S; station located under the crest of equatorial ionospheric anomaly), Brazil. In addition, total electron content (TEC) measurements from several GPS receiving stations in the Brazilian sector during this storm are presented. The simultaneous ionospheric sounding observations carried out at SJC and PAL, and TEC observations on 3 consecutive days viz., 19 November (quiet), 20 November (disturbed) and 21 November (recovery phase) are presented. Salient features from the ionospheric observations in the Brazilian sector during the superstorm are discussed. The difference in the observed ionospheric response at the two stations (PAL and SJC) is considerable. This is not surprising given that PAL is close to the magnetic equator and SJC is near the crest of the equatorial ionospheric anomaly (EIA). It should be pointed out that soon after the SSC (about 4 h later), the F-region critical frequency (foF2), the F-region peak height (hpF2), and variations of virtual heights at different frequencies (iso-frequency plots) all show wavelike oscillations of the F-region during daytime at both the ionospheric sounding stations. Unusual rapid uplifting of F-region at PAL was observed during both the main and recovery phases of the storm.

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