Comparison of Storm-Time Changes of Ionospheric Total Electron Content at Nearby Locations in Mid-Latitudes

Abstract

The changes in the total electron content (TEC) at some mid-latitude locations in the American zone are compared during nine geomagnetc storms which are comparatively clean (clear-cut single main phase). It is found that TEC changes are sometimes related to sudden storm commencement (SSC) and sometimes to main phase onset (MPO) and the changes are sometimes positive and sometimes negative with no obvious relationship either with season or with any particular phase of the geomagnetic storm. It is concluded that there is no direct cause-effect relationship between ionospheric changes and changes of geomagnetic field as such and the only thing common between these is their common source viz, impact of interplanetary plasma blobs while subsequent evolutions are independent and unrelated.