EFFECTS OF GEOMAGNETIC SUPER STORMS ON THE IONOSPHERIC F-REGION IN THE SOUTH AMERICAN SECTOR USING A GPS TECHNIQUE: A REVIEW

Y. SAHAI; A. J. DE ABREU; P. R. FAGUNDES; R. DE JESUS; G. CROWLEY; M. V. KLIMENKO ; V. V. KLIMENKO; C. BRUNINI; M. GENDE; V.G. PILLAT; J.R. ABALDE; J.A. BITTENCOURT

Asian Journal of Physics

ANITA PUBLICATIONS

Lugar: Meerut; Año: 2011 vol. 20 p. 299 - 319

0971-3093

In the present investigation, the effect of several super storms on the ionospheric region covering the South American sector (Brazil and Argentina) has been studied using a GPS technique. The super storm periods studied include geomagnetically quiet, disturbed and arecovery phases. Considering super storms with |Dst| > 250 nT, four periods with six super storm events have been analyzed. The four periods analyzed are 05-08 April 2000 (only Brazilian sector), 27-31 October 2003 (Brazilian and Argentinean sectors), 19-23 November 2003 (only Brazilian sector), and 06-11 November 2004 (Brazilian and Argentinean sectors). In this review, we present and discuss in a consolidated form during the results obtained by us during these superstorms. Both vertical total electron content (VTEC) and phase fluctuations (TECU/min) from several GPS stations (for which data were available) have been presented. Phase fluctuations are a good indicator of spread-F irregularities with a few km sizes. We have compared the observed TEC at different GPS observing sites during the four periods with the TIME-GCM simulation results. The model results show both similarities and differences from the observed results. Large variations (both positive and negative storm phases) in the VTEC during the main and recovery phases compared to quiet day variation were observed in several super storm events studied. The phase fluctuations indicate the presence of plasma bubbles extending to the Argentinean sector during the post-sunset pre-reversal period of super storms on the nights of 29-30 and 30-31 October 2003, and 07-08 November 2004.