COMPARISON OF TRANSIENT VARIATION OF TOTAL ELECTRON CONTENT WITHIN AND OUTSIDE EQUATORIAL ANOMALY REGION

Abstract

This research work was carried out to compare the Transient variation of Total Electron Content (TEC) within the equatorial ionization anomaly (EIA) region and outside the anomaly region. TEC data were obtain from a GPS-SCINDA system station in the EIA region at the Federal University of Technology Akure in Nigeria (geomagnetic coordinates; lat. 2.65oN, long. 77.2oE) and IGS station in the middle latitude region at Matera in Italy (lat. 34.6oN, long.90.9oE) from 2008 to 2010 were used. The TEC data was analysed base on the international quietest and most disturbed days of the period for the study. The diurnal variation of TEC, shows that there exist a predawn minimum value of TEC between 0300 LT and 0600 LT in both the EIA region and middle latitude. It was also observed that TEC in the EIA region usually peaked around local noon. However TEC in the middle latitude region peaked when it is most enhanced, this often occur either in the noon and post noon sector. In the monthly variation TEC in the EIA region were observed to peaked either at March-April of September-October, this were observed to be equinoctial months. However in the middle latitude the peak of TEC varies base on the intensity of solar radiation received by the region. The study shows that equatorial ionization enhances TEC in the EIA region. The fountain effect of this equatorial ionization was observed to extend into the low-middle latitude, this result in the occurrence of predawn minimum of TEC and the pre-midnight enhancement of TEC. It was further observed that TEC in the EIA region is majorly equatorial ionization development, while TEC in the middle latitude region is majorly controlled by EUV solar radiation and neutral winds.