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.
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.
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 .
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.