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

Abstract

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 |D st | 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 Correspondence to: F. Becker-Guedes (fabio@univap.br) 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.

TEC variations during low solar activity period (2005–2007) near the Equatorial Ionospheric Anomaly Crest region in India

“…A similar increase of TEC was reported for the super storm of 20 November 2003 in the Brazilian low latitude sector by Becker-Guedes et al (2007). The subsequent day decrease (negative storm phase) may be due to thermospheric winds and neutral composition changes produced by the storm time Joule heating.…”

Storm time response of GPS-derived total electron content (TEC) during low solar active period at Indian low latitude station Varanasi

“…Once, this process becomes operative, upward plasma transport takes place, which results into enhancement of VTEC. A similar increase of TEC was reported for the super storm of 20 November 2003 in Brazilian low latitude (Becker-Guedes et al 2007) and for the storm of 24 August 2005 in Indian EIA region (Bagiya et al 2009). The subsequent day (12 October) during the recovery period, decrement in VTEC is observed, which is in the limit of day-to-day variability of the ionosphere.…”

Storm-time ionization enhancements at the topside low-latitude ionosphere

“…Dmitriev (dalex@jupiter.ss.ncu.edu.tw) enhancements of ion and electron density (storm-enhanced density or SED) and temperature at the low-and mid-latitude topside ionosphere are detected by means of in-situ space experiments (e.g. Mannucci et al, 2005;Oyama et al, 2005;Yizengaw et al, 2005) and of remote techniques, such as ionosonde, radar and total electron content (TEC) obtained from GPS signal processing (Tsurutani et al, 2004;Yizengaw et al, 2005;Zhao, et al, 2005;Dabas et al, 2006;Becker-Guedes et al, 2007;Huang et al, 2007).…”