%0 Journal Article %T Time variation of total electron content over Tucum¨¢n, Argentina %A M. Mosert %A R. Ezquer %A C. Jadur %A R. del V. Oviedo %J Geof¨ªsica internacional %D 2004 %I Universidad Nacional Aut¨®noma de M¨¦xico %X The day-to-day variability of total electron content, TEC, at Tucum¨¢n (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. %K Faraday TEC %K equatorial anomaly %U http://www.geofisica.unam.mx/unid_apoyo/editorial/publicaciones/investigacion/geofisica_internacional/anteriores/2004/02/Mosert.pdf