Variations in the equatorial ionization anomaly peaks in the Western Pacific region during the geomagnetic storms of April 6 and July 15, 2000
© The Society of Geomagnetism and Earth, Planetary and Space Sciences (SGEPSS); The Seismological Society of Japan; The Volcanological Society of Japan; The Geodetic Society of Japan; The Japanese Society for Planetary Sciences. 2007
Received: 5 September 2006
Accepted: 15 February 2007
Published: 8 June 2007
This study utilizes total electron content (TEC) observed by a network of ground-based GPS receivers located in the Western Pacific region (∼120°E) to study the responses of the low-latitude equatorial ionization anomaly (EIA) to the two major magnetic storms that occurred during April 4–10 and July 12–18, 2000. The latitude, time, and TEC (LTT) maps in the northern and southern EIA regions show that both EIA peaks move equatorward along with a pronounced reduction of the TEC values 10–12 h after the storm onset. The variations in the EIA peak TEC values and locations in the northern EIA are highly correlated with those in the southern EIA. The correlation coefficients of the day-to-day variations of peaked TEC between the northern and southern EIA regions are 0.75 in the April storm and 0.83 in the July storm. The correlation coefficients of the day-to-day EIA peak movements between the two hemispheres are 0.98 in the April storm event and 0.88 in the July storm event. The highly correlated peaked TEC and movements between the northern and the southern hemisphere suggest that the storm-produced electrodynamics played a dominant role in affecting the low-latitude ionosphere during the two major storms.