A Case Study of Daily and Seasonal Changes in Total Electron Content in Mid-Latitudes Regions in the Period of 2019–2021

The behavior of the total electron content (TEC) on a global scale has been the subject of research for several years. However, certain features of this behavior, including the effectiveness of energetic particles and their anomalies at different latitudes, are poorly understood. This research reports a comparative analysis of the seasonal and daily changes in the TEC as observed from 2019 to 2021 (low solar activity) in the mid-latitudes between 33.1 and 40.1 degrees. The points include eight stations across four countries with the following coordinates: Tehran (Iran), Hamedan (Iran), Tabriz (Iran), Yerevan (Armenia), Diyarbakir (Turkey), Ankara (Turkey), Nicosia (Cyprus), and Baghdad (Iraq). Also, by taking the quiet solar activity conditions into account, TEC’s variations have been investigated hourly, daily, and seasonally. For this research, TEC observations from the Global Positioning System (GPS) have been analyzed. The results showed that the highest TEC values occurred during 0900–1100 UT (1300–1500 LT), and the lowest values occurred during 2400–0200 UT (400–600 LT). From a seasonal point of view, in 2019, the maximum value of TEC was observed during the March equinox, and the lowest maximum value of TEC was observed during the December solstice, but in 2020 and 2021 the maximum value of TEC was observed during the June solstice and September equinox, the lowest value of TEC is observed during the December solstice.