Differences between GPS and digisonde measurements of Total Electron Content at Tucumán

Abstract

Measurements of Total Electron Content (TEC) were obtained from GPS and digisonde data, at Tucum´an (26.69◦S, 65.23◦W), for days in different seasons, and with different geomagnetic activities, in 2004. Differences between both methods — associated with plasmaspheric content — are analyzed regarding hourly behavior, magnetic activity, and season; and are also compared with other latitude data. Results show a general good agreement between both methods, GPS measurements being generally higher around the diurnal maximum; results agree with theoretical predictions and findings from other authors as well. Maximum TECs occur in equinox, particularly, on magnetically perturbed days. Concerning the plasmaspheric content, our results do not show clear differences between quiet and perturbed days. The seasonal behavior can be associated with variations of the equatorial anomaly.