Tertyshnikov A.V.,Fedorov Institute of Applied Geophysics
Izvestiya, Physics of the Solid Earth | Year: 2017
The results of calculating the characteristics of the pseudopositioning of two navigational receivers in Tuapse and 60 km north of Tuapse at the Goryachii Klyuch locality before and after a weak submarine earthquake are presented. The earthquake with the epicenter 2 km offshore of Tuapse occurred on September 8, 2010. The experiment was conducted with the satellite receivers recoding the signals of the GLONASS/GPS global navigational satellite systems (GNSS). The receivers pertain to the system of satellite monitoring and forecasting the natural and manmade hazards on the segment of the North Caucasian Tuapse–Adler railroad. The pseudopositioning calculations based on the first carrier frequency of a GLONASS/GPS GNSS are conducted by the original author’s technology for monitoring the ionosphere and geological motions. It is established that the errors of the pseudopositioning estimates increase by the time of the earthquake. The accompanying effects in the variations of the ionospheric electron density and in the state of the Earth’s magnetic field are considered. The obtained results complement the existing data on the dynamics of the precursors of the earthquakes. © 2017, Pleiades Publishing, Ltd.
Zabaydullin O.,Fedorov Institute of Applied Geophysics |
Dubau J.,LUTH |
Dubau J.,University Paris - Sud
Journal of Physics B: Atomic, Molecular and Optical Physics | Year: 2012
For He-like ions, photoabsorption and photoionization cross-sections of 1s 2 can differ in the resonance region due to possible resonance radiative decays. This difference increases along isoelectronic sequence. As an example, the 2s2p autoionizing state is considered for different atomic elements (Z = 16, 20, 26). For these elements, we use atomic data computed, without radiative damping, by the R-matrix BreitPauli code for 1s 2 and 1s2s photoionization processes, which are available on atomic data websites. Applying Davies and Seaton's (1969 J. Phys. B: At. Mol. Phys. 2 757) radiative damping theory, we insert the damping effect. Comparisons are made with similar data computed by another code, which uses Robicheaux et al's (1995 Phys. Rev. A 52 1319) damping theory, also available on an atomic code website. We also present a very simple approximation of Davies and Seaton's theory, and test it by comparisons of data computed with and without the approximation. © 2012 IOP Publishing Ltd.
Klimenko M.V.,Kaliningrad State Technical University |
Klimenko V.V.,Russian Academy of Sciences |
Zakharenkova I.E.,Russian Academy of Sciences |
Pulinets S.A.,Fedorov Institute of Applied Geophysics |
And 2 more authors.
Advances in Space Research | Year: 2011
The problems of physical explanation and possible mechanisms of the seismo-ionospheric effects formation are under discussion now. There are proposed different mechanisms of such effects, for example, large- and small-scale internal gravity waves (IGWs), atmospheric electric field, electromagnetic fields and emissions. However, the appearance of local large-scale seismo-ionospheric anomalies in Total Electron Content (TEC) is possible to explain only by two mechanisms: an atmospheric electric field and/or small-scale IGWs. In this paper, the simulation results for reproduction of the observed seismo-ionospheric great positive effects in TEC prior to strong Wenchuan earthquake are presented. The obtained results confirm the proposed mechanism of seismo-ionospheric effects formation by the penetration of the seismogenic electric field from the atmosphere into the ionosphere. It is suggested that so great TEC enhancement observed 3 days prior to Wenchuan earthquake could be explained by combined action of seismogenic vertical electric field and IGWs generated by the solar terminator. © 2011 COSPAR. Published by Elsevier Ltd. All rights reserved.
Poluarshinov M.A.,Fedorov Institute of Applied Geophysics
Geomagnetism and Aeronomy | Year: 2014
A method of recording internal gravitational waves (IGWs) from spacecraft by observing disturbances in the atmospheric emission layer, formed in the vicinity of the solar terminator and emitted in the atmospheric molecular oxygen system (762 ± 5 nm), is considered. The possibility of such observations and the efficiency of recording various characteristics of IGWs passing through the observed emission layer are estimated. © Pleiades Publishing, Ltd 2014.
Batakov A.M.,Fedorov Institute of Applied Geophysics
Geomagnetism and Aeronomy | Year: 2012
We present a concept regarding the effectiveness of ionospheric models in maximum usable frequency (MUF) forecasts according to the fitting criterion for daily progress in predicted and experimentally observed MUFs. For example, it is shown using the daily variability in the MUF on two one-leap paths that an MUF model on the basis of a long-term IPG forecast is characterized by efficiency within 0.8. It is shown using the same two paths that a forecast on the basis of the International Reference Ionosphere (IRI) model has the same efficiency. A model of the effectiveness probability density function is constructed on the basis of a generalization of the method of nonholomorphic functions. © 2012 Pleiades Publishing, Ltd.
Klimenko M.V.,Russian Academy of Sciences |
Klimenko V.V.,Russian Academy of Sciences |
Zakharenkova I.E.,Russian Academy of Sciences |
Pulinets S.A.,Fedorov Institute of Applied Geophysics
Advances in Space Research | Year: 2012
The measurements of GPS signal delays show that the local areas of increased/decreased Total Electron Content (TEC) of the ionosphere can be observed before strong earthquakes. The main possible cause of these TEC disturbances is the vertical plasma drift under the action of zonal electric field. The spatial pattern of electric potentials for such electric field was proposed. The model calculations were done to investigate the efficiency of the proposed mechanism. The calculation results revealed the agreement with TEC variations observed before strong earthquakes and showed that the equatorial electrojet variations can be considered as precursors of earthquakes. © 2011 COSPAR. Published by Elsevier Ltd. All rights reserved.
Teterin K.A.,Fedorov Institute of Applied Geophysics
Geomagnetism and Aeronomy | Year: 2013
In view of the popularity of using empirical models in implementing SW radio communication at long distances and in problems of target detection, it became necessary to adapt these models to the real state of the ionosphere so that these models could be used in operational work. It is proposed to adapt the IRI model by optimizing the values of the global ionospheric index and the number of solar spots, i.e., the parameters used in the model when calculating the height distribution of electron concentration in the ionosphere, with the involvement of oblique incidence backscatter sounding data. The problem regarding the correctness of the adaptation problem was considered under some restrictions. An estimate of the adaptation error has been obtained. © 2013 Pleiades Publishing, Ltd.
Shubin V.N.,RAS Institute of Radio Engineering and Electronics |
Karpachev A.T.,RAS Institute of Radio Engineering and Electronics |
Tsybulya K.G.,Fedorov Institute of Applied Geophysics
Journal of Atmospheric and Solar-Terrestrial Physics | Year: 2013
We propose a global median model SMF2 (Satellite Model of the F2 layer) of the ionospheric F2-layer height maximum (hmF2), based on GPS radio-occultation data for low solar activity periods (F10.7A<80). The model utilizes data provided by GPS receivers onboard satellites CHAMP (~100,000 hmF2 values), GRACE (~70,000) and COSMIC (~2,000,000). The data were preprocessed to remove cases where the absolute maximum of the electron density lies outside the F2 region. Ground-based ionospheric sounding data were used for comparison and validation. Spatial dependence of hmF2 is modeled by a Legendre-function expansion. Temporal dependence, as a function of Universal Time (UT), is described by a Fourier expansion. Inputs of the model are: geographical coordinates, month and F10.7A solar activity index. The model is designed for quiet geomagnetic conditions (Kr=1-2), typical for low solar activity.SMF2 agrees well with the International Reference Ionosphere model (IRI) in those regions, where the ground-based ionosonde network is dense. Maximal difference between the models is found in the equatorial belt, over the oceans and the polar caps. Standard deviations of the radio-occultation and Digisonde data from the predicted SMF2 median are 10-16km for all seasons, against 13-29km for IRI-2012. Average relative deviations are 3-4 times less than for IRI, 3-4% against 9-12%. Therefore, the proposed hmF2 model is more accurate than IRI-2012. © 2013 .
Datsko V.N.,Fedorov Institute of Applied Geophysics
Journal of Communications Technology and Electronics | Year: 2016
Experimental data on propagation of electromagnetic waves over the ocean surface along a 235-km path in the frequency range 5–30 MHz are analyzed. It is found that the field attenuation at frequencies below 15 MHz, which is anomalously weak according to the ground ray theory, is related to excitation of surface waves and agrees well with the data obtained in the frequency range 0.6–6.0 GHz. © 2016, Pleiades Publishing, Inc.
Konstantinova A.V.,Fedorov Institute of Applied Geophysics |
Danilov A.D.,Fedorov Institute of Applied Geophysics
Geomagnetism and Aeronomy | Year: 2015
It is shown that the use of initial data series of different lengths is one of the main causes of the difference in the values of trends in the F2-layer parameters, foF2 and hmF2, obtained in a series of publications of the authors and published by other researchers. Arguments are presented in favor of the statement that systematic changes in the F2 layer began around 1980. Searching for trends, the authors consider periods after 1980. At the same time the majority of other scientists use the entire available array of data beginning in 1957 and 1958 (and sometimes even earlier) to search for trends. In that case, the analyzed time interval automatically includes the period before 1980, when the trends were absent. This leads to a substantial underestimation of the magnitude of the obtained negative trends in foF2 and hmF2. Particular examples based on the data of both the authors and other scientists confirming the statement are presented. © 2015, Pleiades Publishing, Ltd.