Geomatik Uygulama ve Araştırma Merkezi, (GEOMER) / Geomatics Application and Research Center
Permanent URI for this collectionhttps://hdl.handle.net/11413/6776
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Browsing Geomatik Uygulama ve Araştırma Merkezi, (GEOMER) / Geomatics Application and Research Center by Subject "Ionosphere"
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Publication Metadata only Relations between the GNSS, InSAR, and the other techniques for prediction of earthquakes(Springer Heidelberg, Tiergartenstrasse 17, D-69121 Heidelberg, Germany, 2015-09) Urusan, Ahmet Y.It is a well-known fact that the earthquakes have a lot of different parameters. Modern technology allows us to observe an important part of these settings. For example, when an earthquake occurs, its location, time, and depth, etc., values are measured by a seismometer. Recently, using the modern technologies, Global Positioning System (GPS) and Interferometric Synthetic Aperture Radar (InSAR) give us a chance to predict earthquakes in the short or long term. For avoiding the destruction the force of an earthquake can bring to human beings, it is inevitable to use the newer techniques. To predict out about the expected main shock, someone must begin to study firstly earthquakes which have already occurred. In this research, the seismometer and acceleration-meter data have been evaluated and compared by the geodetic measuring data of the InSAR and GPS data for Van earthquake on 23 October 2011. The area of research made out by the InSAR technique and the deformations produced by the GPS technique are being tested under centimeter precision. Additionally, the ionospheric total electron content values obtained by the GPS method have been considered, and the ionospheric distortions acquired from the closest Continuously Operating Reference Stations-Turkey stations, particularly Muradiye station, have been observed. Also, they have been interpreted geophysically.Publication Metadata only The Ionospheric Refractivity Effects on the GPS Signals(IEEE, 345 E 47Th St, New York, Ny 10017 Usa, 2013) Ünver, Onur; Guyer, Sinan; Uzel, Turgut; Can, Zehra; 9308; 2759The communication between the global navigation satellites and ground observation stations is provided by the electromagnetic waves that emits from the satellites. When the satellite signals pass through the Ionosphere, they are refracted by the different Ionospheric layers. The precise determination of the Ionospheric refractivity index is crucial for the evaluation of the Ionospheric delay that depends on the refraction ratio. The electromagnetic waves that passes through the Magnetoionic medium interacts with the medium depending upon the free electron content and plasma frequency. As a consequence of that interaction the medium shows the dispersive and refractive effects on the waves. The phase and group velocity of an electromagnetic wave in the vacuum are equal and advances with the speed of light, on the other hand in the plasma medium there is a relativistic difference between the phase and group velocities, and this difference depends on the refractivity index of the medium. The refractivity shows varieties depending upon the free electron content of the medium, external magnetic field, gyrofrequency of electrons and plasma frequency. In the earth's atmosphere the layer that locates the altitude 501000 km and contains free electrons and positive ions as a result of the effects of the solar radiation and solar energetic particles is called as Ionosphere. In the Ionosphere, the thermal effects on the electrons are low level so this region is termed "cold plasma". In the Ionospheric researches, due to mass of the positive ions higher than mass of the electrons, ion motions are neglected. In terms of quality and quantity, Ionosphere shows the Magnetoionic medium effects on the electromagnetic waves. In this study, the variations of the Ionospheric refractivity index on the GPS signals due to different Ionospheric conditions is examined and made a comparison with the results of the literature.