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 |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.

Highlights

  • The response of ionosphere-thermosphere system in the equatorial and low latitude region during super geomagnetic storms or superstorms are important space weather issues

  • Investigations related to magnetosphere-ionosphere interactions during geomagnetic storms at equatorial and low latitude continue to attract considerable attention because more case studies are needed to understand better different types of space weather events and increase our capability to predict ionospheric responses

  • In this paper we have presented the simultaneous ionospheric sounding observations from to stations Palmas (PAL) and Sao Josedos Campos (SJC) located in the Brazilian sector, during the superstorm on 20 November 2003

Read more

Summary

Introduction

The response of ionosphere-thermosphere system in the equatorial and low latitude region during super geomagnetic storms or superstorms (we have considered a geomagnetic storm with |Dst |max>250 nT as superstorm) are important space weather issues. This 2 Observations impact resulted in a superstorm with a storm sudden commencement (SSC) at 08:03 UT (20 November) attaining The two ionospheric sounding stations (PAL and SJC) have

Results
Conclusion
Full Text
Published version (Free)

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call