![]() ![]() This study focuses on the analysis of the variations of ionosphere over Turkey that can be grouped into anomalies during equinox and solstice periods using TEC estimates obtained by a regional GPS network. Global Positioning System (GPS) recordings can be utilized to estimate the TEC, thus GPS proves itself as a useful tool in monitoring the total variability of electron distribution within the ionosphere. Total Electron Content (TEC) is the integral of the electron density along a ray path that indicates the total variability through the ionosphere. ![]() Ionospheric electron density is the determining variable for investigation of the spatial and temporal variations in the ionosphere. Ionospheric responses during equinox and solstice periods over Turkey This study is supported by TUBITAK EEEAG 114E541 a part of the Scientific and Technological Research Projects Funding Program. SKLD and L2N values in the solstice are larger than those in the equinox. It is observed that the difference between solstice and equinox periods increases related to the upgrading geomagnetic activity. The solstice and equinox periods within the same year and the solstice periods and the equinox periods from 2010 to 2012 are compared with each other for 18 Turkish National Permanent GPS Network (TNPGN-Active) stations. In this study, the behavior of the IONOLAB- Total Electron Content (TEC) estimates obtained from dual frequency ground-based GPS receivers are examined using Symmetric Kullback Leibler Distance (SKLD) and L2 Norm (L2N) methods both for the periods that include the equinox and solstice between 20 for Turkey. Therefore, relying on the evidence that there have been variations observed in the VLF, LF and HF signals, magnetic field of the earth and in the local electric field, a unified theory, that would explain the mechanism and cause of the disturbance in the layers of atmosphere, is a widely investigated research topic. Ionosphere responds to solar EUV radiation by varying within the diurnal 24-hour period, seasonal periods and annually and over the 11-year cycle of solar activity. Ionosphere is a layer of the atmosphere which is an integral part of whole geomagnetic and geological framework. Ionospheric Response during the Equinox and the Solstice Periods over Turkey Additional joint observations are needed to identify the seasonal and longitudinal dependences of TID characteristics. During the summer solstice, the overall wave activity is smaller than during vernal equinox. Relative amplitudes are substantially greater over Millstone Hill, whereas higher absolute amplitudes are observed over Kharkiv. Absolute and relative amplitudes, time of appearance, durations and phase differences of TIDs show strong height and seasonal variability. There is no obvious relationship between the observed wave processes and variations in the auroral electrojet. We found that TIDs with periods of 40-80 min are observed during all measurements and concentrated predominantly near the sunrise and sunset terminators over both sites. The same methods and software were used for analysis of both data sets to ensure consistency. The joint measurements were conducted near the vernal equinox and summer solstice in 2016 using Kharkiv (49.6 N, 36.3 E) and Millstone Hill (42.6 N, 288.5 E) incoherent scatter radars. We present the results of comparative study of traveling ionospheric disturbances (TIDs) obtained at middle latitudes of different longitudinal sectors during two coordinated observational campaigns. Traveling ionospheric disturbances observed by Kharkiv and Millstone Hill incoherent scatter radars near vernal equinox and summer solstice ![]()
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