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Magnetic field secular variations in Ukraine on the base of RS network observations |
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Maksymchuk, V. (1), Orlyuk, M. (2) |
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(1) Carpathian Branch of S.I.Subbotin's Geophysical Institute,Ukrainian academy of Sci., Lviv, Uktaine; (2) S.I.Subbotin's Geophysical Institute, Ukrainian academy of Sci., Kyiv, Ukraine |
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Geomagnetic observations on the RS network let us obtain information about absolute values of magnetic field components, which are the base for normal magnetic field maps plotting. But repeat observations on the RS network give a possibility to obtain magnetic field secular variations (SV) data and information about their spatial structure. Considering size of the investigating area (18 degrees in E-W direction and 8 degrees in N-S direction) the problem of normal geomagnetic field and its SV mapping is very actual for Ukraine. In 2018 SV network in Ukraine consists from 78 points (near 1 SV point in 8,000 sq.km). More, in Ukraine are based 3 magnetic observatories: Kyiv, Lviv, Odesa. Recent RS network was founded during 2003-2004 yrs. And first cycle of observations was fulfilled. Repeat observations were done during 2010-2011 yrs. The results were the base for maps of secular variations, X, Y, Z, F, D components for 2010-2005 years. Especially complex SV spatial structure in all magnetic field components was stated. Few anomalous zones of F SV morphology in Ukraine are defined. Minimum values of SV are characteristic in Transcarpathians (28 nT/per year), Volyno-Podillya (30 nT/per year), Crimea Peninsula (30 nT/per year). Central and Eastern parts of Ukraine are characterized by mosaic SV structure of F field with some isometric anomalies, proved only by one SV point. Comparison of SV spatial structure, based on the SV points data and IGRF model shows essential differences. Deviation from IGRF model for F, Z components were defined in active seismic regions of Carpathians and Crimea (-2-3 nT/per year), for Volyno-Podillya and Donbass (2-3 nT/per year). The same time close correlation of SV anomalies structure with anomalous magnetic field can be observed. It testifies Earth’s lithospheric sources impact in magnetic field SV. The next repeatable geomagnetic observations cycle on the Ukrainian SV network is planned in 2019-2020 yrs. |
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