A case study of Daily and Seasonal Changes in Total Electron Content in mid-latitudes Regions in the Period of 2019-2021

Abstract

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 paper reports a comparative analysis of the seasonal and daily changes in the total electron content (TEC) as observed from 2019 to 2021 during the 11-year solar cycle in eight stations 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) (35.6 N; 51.5 E), Hamedan (Iran) (34.6 N; 48.5 E), Tabriz (Iran) (38.1 N; 46.5 E), Yerevan (Armenia) (40.1 N; 44.5 E), Diyarbakir (Turkey) (37.6 N; 40.5 E), Ankara (Turkey) (39.6 N; 33.0 E), Cyprus (Cyprus) (35.1 N; 33.5 E), and Baghdad (Iraq) (33.1 N; 44.5 E). Also, by taking the quiet solar activity conditions into account, TEC’s variations are investigated hourly, daily, and seasonally. For this research, absolute total electron content (ATEC) observations from Global Positioning System (GPS) have been analyzed. The results showed that the highest TEC values occurred during 08:00–12:00 UT (12:00–16:00 LT), and the lowest values occurred during 23:00–02:00 UT (3:00–6:00 LT). From a seasonal point of view, in 2019 and 2020, the maximum value of TEC is observed during the March equinox and the September equinox, respectively, and the lowest maximum value of TEC is observed during the December solstice, but in 2021, the maximum value of TEC is observed during the June solstice and the lowest maximum value of TEC is observed during the December solstice.