Browsing by Author "Karatay, S"
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Web of Science Classification of the Ionospheric Disturbances Caused by Geomagnetic and Seismic Activity with K-Nearest Neighbors Algorithm(2024.01.01) Budak, C; Karatay, S; Erken, F; Cinar, AWeb of Science Comparison of Design Gmrt Wind Turbine Plant Effectively with other Power Wind(2017.01.01) Hancerliogullari, A; Sener, YA; Unal, S; Karadeniz, M; Hancerliogullari, G; Kurnaz, A; Cetiner, MA; Ashufat, SA; Madee, YGA; Karatay, SWeb of Science Publication Detection of the ionospheric disturbances on GPS-TEC using Differential Rate Of TEC (DROT) algorithm(2020-05-15) Karatay S.; Karatay, SThe solar, geomagnetic, gravitational and seismic activities can cause spatial and temporal (hourly, diurnal, seasonal and annual) variabilities of the ionosphere. Main observable ionospheric parameters such as Total Electron Content (TEC) can be used to quantify these. TEC is the total number of electrons on a ray path crossing the atmosphere. The network of world-wide Global Positioning System (GPS) receivers provide a cost-effective solution in estimating TEC over a significant proportion of global land mass. This study is focused on the analysis of the variations of ionosphere over a midlatitude region using GPS-TEC estimates for three Sun Spot Numbers (SSN) periods. The investigation is based on a fast and automatic variability detection algorithm, Differential Rate Of TEC (DROT). The algorithm is tested using literature data on disturbances generated by a geomagnetic activity, a Solar Flare, a Medium Scale Travelling Ionospheric Disturbance (MSTID), a Large Scale TID (LSTID) and an earthquake. Very good agreement with the results in the literature is found. DROT is applied to IONOLAB-TEC estimates from nine Turkish National Permanent GPS Network (TNPGN Active) stations over Turkey to detect the any wave-like oscillations, sudden disturbances and other irregularities during December, March, June, September months for 2010, 2011, 2012 years. It is observed that DROT algorithm is capable of detecting both small and large scale variability due to climatic, gravitational, geomagnetic and solar activities in all layers of ionosphere. The highest DROT values are observed in 2010 during winter months. In higher solar activity years of 2011 and 2012, DROT is able to indicate both seasonal variability and severe changes in ionosphere due to increased number of geomagnetic storms and local seismic activities.Publication Estimation of frequency and duration of ionospheric disturbances over Turkey with IONOLAB-FFT algorithm(2020-09-01) Karatay S.; Karatay, SOne of the more common methods of observation of variability of the Earth’s ionosphere is based on total electron content (TEC) estimated from ground-based dual-frequency Global Positioning System (GPS) receivers. Variations in solar, geomagnetic and seismic activity cause depletions or enhancements in the ionospheric electron concentrations that can be detected as disturbances. Some of these disturbances have wave-like characteristics, where frequency of oscillation can be used to identify and classify the disturbance. In this study, the frequency of such periodic disturbances is estimated using a fast Fourier transform (FFT)-based method, namely IONOLAB-FFT, in the spectral domain. IONOLAB-FFT, which was initially developed to be used on slant TEC (STEC), is modified to be applied to TEC in the local zenith direction of the receiver. The algorithm is tested using literature data on disturbances generated by a geomagnetic activity, a solar flare, a medium-scale traveling ionospheric disturbance (MSTID), a large-scale TID (LSTID) and an earthquake. An accordance with these known disturbances is observed in running IONOLAB-FFT, and the main frequencies and durations of the disturbances are estimated. IONOLAB-FFT method is applied to TEC computed from Turkish Permanent GPS Network (TNPGN-Active) which lies in mid-latitude region to detect the any wave-like oscillations, sudden disturbances and other irregularities during December, March, June and September months for 2010, 2011 and 2012 years. It is observed that a large number of the estimated frequencies are accumulated between 0.08 and 0.14 MHz corresponding to periods of 3.5 h to 2 h. The significant frequencies are grouped less than 0.28 MHz. A large number of the durations of the oscillations are between 425 and 550 min in 2010, 300 and 550 min in 2011 and 350 and 400 min in 2012. The longest duration (around 800 min: 13.33 h) is observed in December months, and the shortest duration (around 2 h) is observed in September months.Web of Science Web of Science Ionospheric responses during equinox and solstice periods over Turkey(2017.01.01) Karatay, S; Cinar, A; Arikan, FWeb of Science Prediction of GPS-TEC on Mw > 5 Earthquake Days Using Bayesian Regularization Backpropagation Algorithm(2023.01.01) Karatay, S; Gul, SEWeb of Science Seasonal Variations of Impedance in the Ionospheric Plasma(2020.01.01) Unal, I; Karatay, S; Yesil, A; Hancerliogullari, AWeb of Science SPACE WEATHER STUDIES OF IONOLAB GROUP(2016.01.01) Arikan, F; Sezen, U; Toker, C; Artuner, H; Bulu, G; Demir, U; Erdem, E; Arikan, O; Tuna, H; Karatay, S; Gulyaeva, TL; Mosna, ZWeb of Science Spatio-Temporal Prediction of Ionospheric Total Electron Content Using an Adaptive Data Fusion Technique(2019.01.01) Erken, F; Karatay, S; Cinar, AWeb of Science Publication Temporal variations of the ionospheric disturbances due to the seasonal variability over Turkey using IONOLAB-FFT algorithm(2020-05-01) Karatay S.; Karatay, SThe ionosphere is exposed to forcing from below due to gravitational, geomagnetic and seismic activities, and above due to solar wind. These forces cause some medium and large scale irregularities and disturbances into the upper atmosphere and ionosphere. Some of these disturbances occur in the form of wave-like oscillations in the ionosphere which propagate at a certain frequency, duration and velocity. These disturbances can be detected by monitoring the ionosphere using Total Electron Content obtained from Global Positioning System (GPS-TEC). In this study, the temporal analysis of these disturbances due to the seasonal variability is carried out for a mid-latitude GPS network using Ionosphere Research Laboratory TEC (IONOLAB-TEC) over Turkey. The IONOLAB Fast Fourier Transform (FFT) algorithm is applied to GPS-TEC obtained from nine Turkish National Permanent GPS Network (TNPGN) active stations in Turkey for December (winter solstice), March (spring equinox), June (summer solstice), September (autumn equinox) months in 2010 (low solar activity), 2011 and 2012 (moderate solar activity). It is observed that the highest frequency accumulates around 0.2 mHz at morning and afternoon hours while it accumulates around 0.1 mHz at noon and night hours. The frequency increases from solar quiet year 2010 to solar quiet active year 2012. In all years, it is observed that most frequencies are grouped at higher frequencies for the equinox months. The lower frequencies are observed for the solstice months for all time intervals. The largest numbers of the durations accumulate around 100 min (1.66 h) for morning hours, 200 min (3.33 h) for noon hours, 200 min (3.33 h) for afternoon hours and 150 min (2.5 h) for night hours. After sunrise and sunset, the durations of the disturbances are shorter than those observed for noon and afternoon times. The duration shortens from solar quiet year 2010 to solar quiet active year 2012. The durations for equinox months are shorter than those for the solstice months.Web of Science The relationship between the Quasi Biennial Oscillation and Sunspot Number(2015.01.01) Sagir, S; Karatay, S; Atici, R; Yesil, A; Ozcan, OWeb of Science The Seasonal Anomalies in Ionosphere over Turkey(2016.01.01) Cinar, A; Karatay, S; Arikan, F