Investigation of ionospheric TEC anomalies caused by space weather conditions

Abstract

This study examines the influence of space weather conditions on ionospheric TEC variations at different latitudes around the world. According to the space weather condition indices (geomagnetic storm-activity indices, solar activity indices, magnetic field change indices, plasma density and proton flux indices) different time periods were chosen. GPS observations were used to obtain TEC data derived from International GNSS Service (IGS) stations located at northern and southern hemisphere latitude regions (equatorial, mid-latitude and high latitude). GPS TEC data were evaluated associated with the space weather conditions using 15-day running median statistical analysis method. The results showed that besides the commonly used geomagnetic storm-activity and solar activity indices, plasma density, magnetic field change and particle flux indices are also important in determining whether there is any TEC anomaly in the ionosphere. This study illustrated that all indices should be examined in the applications associated with the ionosphere and particularly in the research of pre-earthquake ionospheric anomalies.