Browsing by Author "Cinar A."

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Ionospheric responses during equinox and solstice periods over Turkey
(2017-11-01) Karatay S.; Cinar A.; Arikan F.
Ionospheric electron density is the determining variable for investigation of the spatial and temporal variations in 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. 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. 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. It is observed that noon time depletions in TEC distributions predominantly occur in winter for minimum Sun Spots Numbers (SSN) in the central regions of Turkey which also exhibit high variability due to midlatitude winter anomaly. TEC values and ionospheric variations at solstice periods demonstrate significant enhancements compared to those at equinox periods.
Spatio-Temporal Prediction of Ionospheric Total Electron Content Using an Adaptive Data Fusion Technique
(2019-12-01) Faruk Erken; Karatay S.; Cinar A.
Abstract: The ionosphere, a part of upper atmosphere, plays an important role on the propagation of radio waves. Hence, understanding, remote sensing and monitoring of the ionospheric phenomena can provide a compressive description to the physical process that are affected by the behavior of ionosphere. One of descriptive quantity of ionosphere is Total Electron Content (TEC). TEC is the total number of electrons integrated between two points and characterized by observing carrier phase delays of received radio signals transmitted from satellites located above the ionosphere, often using Global Positioning System (GPS) satellites. In this study, TEC is predicted from TEC estimates obtained from GPS network located in Turkey in space and time using an Adaptive Data Fusion Technique (ADF). It is observed that characteristic distributions of the predict TEC and original TEC values are similar with each other. Mean Square Errors are less than 4 TECU. ADF has a high performance for the spatio-temporal prediction when the results are compared with the techniques used in the related studies in the literature.
The seasonal anomalies in ionosphere over Turkey
(2016-06-20) Cinar A.; Karatay S.; Arikan F.
The ionosphere is a region on the Earth's upper atmosphere which extends between 50 km to 1000 km from the ground. It is a layer that consists gases which are ionized by solar radiation. Solar radiation and incident angle of the Sun is important to understand how the Ionosphere affects the radio waves. Total Electron Content (TEC) is one of the important parameters that characterizes Ionosphere and directly related with the Sun's activity. The Ionosphere reflects radio waves and provides communication to distance places in short wave radio communication. In this study, behaviours of the Ionosphere in Turkey are examined for soltice and equinox periods between the years 2009 and 2012 which are one of solar minima and solar maxima periods, respectively by using Symmetric Kullback-Leibler Distance and L2 Norm methods.