Comparison of Transient Variation of Total Electron Content within and Outside Equatorial Ionization Anomaly Region

Abstract

This research analyzed the Transient (Quiet and disturbed conditions) variation of Total Electron Content (TEC) within the Equatorial Ionization Anomaly (EIA) region and outside the anomaly region in the area of ground Global Positioning System (GPS) stations at Federal University of Technology Akure (FUTA) in Nigeria (a station in the EIA region) and Matera in Italy (a station in the middle latitude region) for period of 2008 to 2010. The work shows variation of TEC in function of the daily timing, geographical positioning of the studied area and seasons. The study correlates the TEC to the development of the investigated regions and to the variation of ultraviolet solar radiation and neutral winds. The data were collected using special equipment (Novatel GSV 4004B GPS SCINDA system installed at FUTA Nigeria by the US Air Force Research Laboratory (AFRL) USA (PI-keith Groves)) and the International GNSS Service (IGS) GPS system at Matera Italy. The diurnal variation shows TEC maximum on afternoon, for quiet days and almost similar variations, with small changes for the disturbed days. The difference observed between quiet and disturbed days are correlated with different space weather conditions. A predawn minimum (low in EIA region) and pre-midnight enhancement (higher at EIA region) were observed in each area investigated. Similarly the monthly and seasonal variations were analyzed. The study shows that TEC value is usually higher at the EIA region than the middle latitude region. But when storms occurs TEC Value at the middle latitude is higher. It observed from the study that TEC in the EIA region is mainly controlled by the EIA development, while the TEC variation in the middle latitude region is controlled by extreme ultraviolet solar radiation and neutral winds.