GPS-Total electron content variability in Brazil during low solar activity
Abstract
Variations of ionospheric Total Electron Content (TEC) have been calculated using GPS data obtained over a low latitude station Presidente Prudente, Brazil (22.1o S; 51.4o W ) in 1997, a period of low solar activity. Two hourly TEC averages are presented for the period. Diurnal, seasonal, solar activity variations and the Equatorial Anomaly effects are discussed. TEC diurnal means compared with IRI-95 predictions for equinoxes and solstices months showed that IRI-95 systematically overestimates the observed values. Pre-midnight TEC enhancements were observed all over the year, except in May and June. The TEC values measured reproduce the same general trend of the TEC observations over Cachoeira Paulista, Brazil (22.5o S 45o W). The "fountain" effect seems to be more effective at Presidente Prudente because of its lower magnetic dip latitude. A correlation between TEC experimental values and low solar flux (62 < F10.7 < 116 flux units) emphasizes the inadequacy of IRI to model low latitude TEC values at low solar activity periods. These are the first results obtained using TEC-GPS technique for total electron content measureme n t s at low latitudes in Brazil.
- Publication:
-
34th COSPAR Scientific Assembly
- Pub Date:
- 2002
- Bibcode:
- 2002cosp...34E2610M