GPS based measurements of total electron contents at low latitude ground station Varanasi

SINGH A.K.; SANJAY K; SINGH R. P; AZPILICUETA FRANCISCO; BRUNINI CLAUDIO

Ooty, India

Simposio; National Space Science Symposium; 2008

India National Space Science

The equatorial ionospheric anomaly (EIA) is characterized, in terms of latitudinal distribution of ionization, by a trough at the day magnetic equator and a crest at ~ 17° on either side of the magnetic equator (Appleton, 1946).The cause of anomaly is often attributed to the so called “fountain effect” (Duncen, 1960). The development of the equatorial ionospheric anomaly is as seen in the total electron content (TEC). TEC is the integral of electron number density along the line of sight path from an observer to a satellite, and can vary dramatically day to day (Rastogi & Klobuchar, 1990). Huang and Chang (1996) reported that the strength of the equatorial anomaly reveals semiannual variations and increases with solar activity. Wu et al. (2004) studied seasonal effects on the characteristics of the anomaly crest by analyzing TEC data acquired from a chain of nine ground GPS stations at Taiwan during the period of Sunspot minimum activity. They found that the locations of the anomaly crest are scattered in latitude and local time, do not correlate with the season, and magnetic activity. They demonstrated that the monthly EIA was well correlated with Dst-index and weakly correlated with F10.7. In this paper, we studied seasonal effects on the characteristics of the anomaly crest by analyzing TEC derived from GPS data recorded at low latitude station Varanasi (geomagnetic. lat 14°, 55’N, long. 154°E), near anomaly crest region during the period May 2007 to December 2007.