నైరూప్య

VARIATIONS OF TEC OVER BANGALORE STATION DURING THE YEAR 2003

N. Venkateswara Rao , T.Madhu, Sk. Bibibathula, P.Prathyusha and Y. Anusha

Satellite-Based Augmentation Systems (SBASâ�?�?s) are useful to aid the civil aviation in precision approach and other applications. India is developing its own navigation system, „GAGANâ�?�? (GPS Aided GEO Augmented Navigation), which is expected to become operational by 2014. A major concern that compromises accuracy in these systems is the fluctuating TEC at low latitudes which also displays steep horizontal gradients. The TEC values obtained from the SOPAC (Scripps Orbits and Permanent Array Center) data archive of the IGS (International GNSS (Global Navigation Satellite Systems) Service) for Bangalore Station(13.030N,77.510E),India show large variations, which can adversely affect the Indian GAGAN requirements. The TEC variations for quiet & storm days, their comparison with the IRI (International Reference Ionosphere) obtained over a period of one year (2003) give important features of the Indian low latitude region.