Delayed Ionospheric Response to Solar Activity: Influence of Geomagnetic Activity

The role of geomagnetic activity in the delayed response of the ionosphere along with the solar influences was investigated through a series of controlled simulations of the National Center for Atmospheric Research Thermosphere-Ionosphere-Electrodynamics General Circulation Model under conditions of moderate geomagnetic storms during varying solar activity. In addition, observed ionospheric total electron content data sets were used to investigate the ionospheric delay and to compare it with the model simulations. The ionospheric delay varies spatially and seasonally depending on the solar and geomagnetic activity conditions. The simulations show a global decrease in ionospheric delay during Northern Hemisphere spring, except at high-latitudes in the Northern Hemisphere under moderate geomagnetic activity. The delay increases in the Western Hemisphere during the winter season. We found that the ionospheric delay during the 27-day solar rotation period changes based on whether geomagnetic activity occurs before or after the peak solar rotation day. This study emphasizes the significance of considering the geomagnetic activity when calculating ionospheric delay.