Türkiye ve Balkanlarda Güneş Etkin Yıllarda İyonküre Yönseme Modellemesi

In the context of space-based navigation, guidance, and positioning systems, the characterization of the ionospheric trend model holds critical importance. The Total Electron Content (TEC), defined as the total number of free electrons contained in a cylinder with a cross-section of 1 m² is a fundamental and measurable variable commonly utilized for modeling ionospheric variability. The regional planar trend of TEC over the midlatitude region encompassing a significant portion of Turkey and some Balkan countries has been modeled within a stochastic framework. Median values of the expected value of this planar model as well as its coefficients representing inclination in latitude and longitude were estimated using the Least Squares (LS) approach, taking into account four different years characterized by high solar activity. The expected value of the model indicates that peak values occur during midday hours in March and October, coinciding with the equinoxes, which aligns with seasonal expectations. The smallest variations in the latitude coefficient occur during winter nights, whereas the highest variations are observed during summer midday hours. In the east-west direction, inclination values are evenly distributed, supporting the movement of sunrise and sunset. The highest inclinations are observed in March and October, while the least variation occurs in June and July.