Investigation of variations in Turkey ionosphere during severe geomagnetic storms by using tusaga-active stations

The effects of six severe geomagnetic storms occurring in the 24th solar cycle on the Turkey ionosphere were investigated using six stations (datc, hors, midy, oniy, tekr and vezi) in the Turkey National Basic GNSS Network-Active (TUSAGA-Aktif) system. Total Electron Content (TEC) values, which characterize the ionospheric exchange, were calculated from these stations using IONOLAB-TEC software. TEC values were calculated separately for geomagnetically disturbed and calm situations. Statistically Differential and Differential ROT (DROT) methods were used to detect the ionospheric response in severe geomagnetic storms. According to the results obtained with these methods, it can be stated that positive and negative ionospheric storms occur in the ionosphere of Turkey. Positive storms also occurred in the main phase of the storm, while negative ionospheric storms occurred in the return phase. In addition, according to the difference method in this study, it can be stated that an ionospheric storm did not occur over the ionosphere of Turkey during the severe geomantic storms that occurred in the last years of the 24th solar cycle. According to the DROT method, it can be stated that medium-sized ionospheric disturbances occur on all days that are geomagnetically disturbed on the Turkey ionosphere in the first three storms. However, in the last three storms, it can be stated that large-scale ionospheric perturbations have occurred in the main phase of the storm in general. However, it can be stated that the severe storm of August 2018 caused large-scale ionospheric perturbations on all geomagnetically disturbed days. In the light of these findings, it can be stated that solar winds and the magnetic field of the earth cause positive and negative storms on the Turkey ionosphere, but not continuously, and cause medium and large-scale ionospheric disturbances. Because both large and medium-sized ionospheric perturbations and negative and positive ionospheric storms can have significant impacts on radio communications, satellite-based navigation systems, and other ionospheric-based technologies, monitoring and understanding these disturbances is crucial to mitigate their effects and develop more robust systems.