Time variation of total electron content over Tucumán, Argentina

The day-to-day variability of total electron content, TEC, at Tucumán (26.9S; 294.6E; Dip: -21.1) has been studied. The database includes TEC measurements by Faraday rotation during the high solar activity period from April 1982 (R12= 114) to March 1983 (R12= 75). Two variability parameters have been used in the analysis: the standard deviation from the mean values s and the variability index v = (standard deviation/mean value) x100. The diurnal and seasonal variations of both variability parameters have been analyzed. A comparative analysis with the day-to-day variability of critical frequency in the F2 region, foF2, is presented. A table of values of the relative variability v is presented in terms of seasons and typical hours. Additional studies are suggested in order to extend the results to other geographical and geophysical conditions.