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Vol. 1 (1998 year), No. 2
Namgaladze A.A., Martynenko O.V., Volkov M.A., Namgaladze A.N., Yurik R.Yu.
High-latitude version of the global numerical model of the Earth's upper atmosphere
The global numerical model describing the thermosphere, ionosphere and protonosphere of the Earth as a single system has been modified for the polar upper atmosphere studies. The spatial and time resolution of the model has been significantly enhanced by the use of the variable latitudinal steps of numerical integration. The model is being developed to encompass modelling of the inner part of the magnetosphere confined by the closed geomagnetic field lines and the mesosphere. The results of the model calculations for the quiet magnetic conditions have been compared with the data of the empirical ionospheric and thermospheric models as well as with the EISCAT data and, in general, reasonable agreement between theoretical and empirical data has been found. The new high-latitude version of the model has been applied as well to the investigations of the disturbed behaviour of the Earth’s upper atmosphere during geomagnetic substorms and storms and during disturbances in the cusp region. The physical mechanisms of the upper atmosphere responses to the solar wind and magnetospheric forcings have been understood by the use of the model in several case studies.
(in English, стр.62, fig. 44, tables. 0, ref 145, MS Word 95, MS Word 95 956 Kb)
Vol. 4 (2001 year), No. 1
Namgaladze A.A., Bogolubov A.A., Kalityonkov N.V., Pivovarov V.G., Sverdlov Yu.L., Uspensky M.V.
Geophysical researches in the Arctic
This paper is an attempt to present a review of the investigations of geophysical processes in the Arctic having been conducted during last years in the MSTU. The basic object of the researches are the physical processes taking place in the near-Earth space above the Arctic, as well as on the global scale, influencing on operation of the space rockets and satellites, radiotechnical systems and long lines of energy transfer. A conclusion has been made that the researches of the geophysical processes in the Arctic conducted at the MSTU are complex, made at high scientific level using the modern computer methods, and very cooperative.
(in Russian, стр.10, fig. 0, tables. 0, ref 73, MS Word 95, MS Word 95 29 Kb)
Vol. 6 (2003 year), No. 1
Namgaladze A.A., Namgaladze A.N., Fadeeva Yu.V., Goncharenko L.P. and Salah J.E.
Lower thermosphere and ionosphere behaviour during a strong magnetic storm of March 31, 2001: Modelling and comparison with the Millstone Hill incoherent scatter radar measurements
The numerical global Upper Atmosphere Model (UAM) has been used for studying the lower thermosphere and ionosphere behaviour during a strong magnetic storm of March 31, 2001. A comparison of the calculation results with the Millstone Hill IS radar data obtained during this magnetic storm has been carried out. A satisfactory agreement between the measured and calculated ion temperatures, electron and ion drift velocities has been obtained. The calculated electric field variation is similar to the observed one but is twice less in magnitude. As to the neutral horizontal wind velocities, there is a large difference between the calculated values and data obtained by the Millstone Hill IS radar, down to the different signs of the wind components. This difference can be bound up to distinctions in the frequencies of the ion-neutral collisions dependent on the neutral atmosphere parameters and the ion composition, and in the electric fields measured at Millstone Hill and theoretically calculated by the UAM. The reasons of the discrepancy of the thermospheric winds simulated by the UAM and calculated at Millstone Hill have been examined. The results of this examination show that the Millstone Hill wind results are very sensitive to the measured electric field values especially when the last are so large as they were in the case, and therefore even a moderate difference between the calculated and observed electric fields may cause a significant discrepancy of the thermospheric winds simulated by the UAM and calculated at Millstone Hill.
(in English, стр.6, fig. 11, tables. 0, ref 7, MS Word 95, MS Word 95 495 Kb)
Vol. 6 (2003 year), No. 1
Shapovalova Yu.A., Namgaladze A.A. and Namgaladze A.N.
The main ionospheric trough stratification as a result of the noncoincidence of the Earth's geomagnetic and geographic axes
By the use of the global numerical upper atmosphere model (UAM) an investigation of the influence of the noncoincidence of the Earth's geomagnetic and geographic axes on the electron density distribution within the main ionospheric trough have been performed for the quiet geophysical conditions. It has been shown, that noncoincidence of the axes causes not only appreciable UT-effect, but also the main ionospheric trough stratification. This stratification appears in some longitudinal sectors due to the periodical movements of the magnetospheric convection pattern relatively to the terminator position.
(in Russian, стр.7, fig. 3, tables. 0, ref 23, MS Word 95, MS Word 95 328 Kb)
Vol. 8 (2005 year), No. 1
Doronina E.N., Namgaladze A.A.
Variations of the latitude-longitudinal variations of thermospheric parameters during geomagnetic storms of 17-20 April, 2002
Study of the latitude-longitudinal variations of the Earth's thermosphere parameters depending on geomagnetic conditions has been performed by the method of mathematical modeling. Calculations have been made with use of the theoretical model of the Earth upper atmosphere (UAM) and the empirical model of the thermosphere (NRLMSISE-00). The maps of global distribution of the calculated thermospheric parameters, such as temperature of neutral gas, concentration of molecular nitrogen and atomic oxygen, the ratio of their concentrations, and also the ratio of ratio n(O)/n(N2) in the disturbed conditions to the quiet ones and the velocity of the horizontal thermospheric wind for the moments 1200 and 2400 UT on April 16, 17 and 18 have been plotted. The results show that the geomagnetic storm effects are stronger in UAM, than in MSIS: in the disturbed conditions in average the neutral temperature is 150-200 K higher.
(in Russian, стр.12, fig. 7, tables. 0, ref 19, Adobe PDF, Adobe PDF 935 Kb)
Vol. 8 (2005 year), No. 1
Doronina E.N., Namgaladze A.A., Goncharenko L.P.
Variations of thermospheric parameters above incoherent dispersion stations during geomagnetic storms of 17-19 April, 2002
Study of the geomagnetic storm influence on the Earth's thermosphere behaviour has been performed by the mathematical modelling method. Thermospheric parameters have been calculated by two ways: by solving the continuity, momentum and heat balance equations (the theoretical model UAM) and using the empirical model of the thermosphere - MSISE2000. The calculations with the UAM have been conducted in two versions with various initial conditions: in the version UAM(TM) initial conditions have been taken from the MSIS, and in the version UAM(T5) they have been taken from the quasi-steady state UAM solution obtained by 5-day model runs. The time variations of the following thermospheric parameters have been analyzed: neutral temperature, molecular nitrogen and atomic oxygen concentrations, the ratio n(O)/n(N2) and the meridional component of the thermospheric wind. The comparison of the various calculation versions has shown that the geomagnetic storm effects in the UAM are larger than in the empirical model of the thermosphere, giving better agreement with the incoherent scatter data on the ionospheric electron density.
(in Russian, стр.12, fig. 6, tables. 0, ref 25, Adobe PDF, Adobe PDF 417 Kb)
Vol. 8 (2005 year), No. 1
Knyazeva M.A., Namgaladze A.A.
Mathematical modelling of forming the night middle-latitude maxima of the electron density in the F2-region of the quiet middle-latitude ionosphere and in the Earth plasmasphere
The relative role of the thermospheric wind and electromagnetic drift in forming the night middle-latitude maxima of the electron density has been investigated for the quiet geomagnetic conditions by using the global numerical upper atmosphere model (UAM). It has been shown that the thermospheric wind creates these maxima, and the electromagnetic drift influences on the form and latitude location of the high-latitude side of the higher electron density regions, the latter depends on the value of the electromagnetic drift velocity. It has been found that appreciable UT- and MLT-effects become apparent in the latitudinal location, form and structure of these regions. The night middle-latitude maxima are clearly seen in the Northern Hemisphere near 00:00 UT and in the Southern Hemisphere - near 18:00 UT. The maxima are shifted to the more low latitudes when getting from the evening hours to the postmidnight ones.
(in Russian, стр.12, fig. 12, tables. 0, ref 10, Adobe PDF, Adobe PDF 1700 Kb)
Vol. 8 (2005 year), No. 1
Yurik R.Yu., Namgaladze A.A.
Research of the thermospheric-ionospheric interaction in the disturbed conditions by the example of the magnetic storm of 3-4 April, 1979
Recent numerical results of the upper atmosphere storm modeling have been presented for the strong magnetic storm of 3-4 April 1979 at the high solar activity level. The results have been obtained using the global time-dependent three-dimensional numerical Upper Atmosphere Model (UAM). The cross-polar cap electric potential, the precipitating electron fluxes, and the positions of the auroral oval boundaries have been used as storm-time model input parameters. The time variation of the calculated disturbances along the midday and midnight geomagnetic meridians of the thermospheric parameters at the height 350 km as well as those of the electron number density at the peak of F2-layer have been shown. The role of the electromagnetic plasma drift and thermospheric composition and wind disturbances on the storm-time ionosphere and thermosphere behaviour is discussed. A comparison of the calculated and observed neutral mass density and ionospheric F2-layer critical frequency latitudinal variations demonstrates a good agreement between the model and experimental data.
(in Russian, стр.14, fig. 9, tables. 1, ref 21, Adobe PDF, Adobe PDF 1300 Kb)
Vol. 12 (2009 year), No. 2
Namgaladze A.A., Zolotov O.V., Zakharenkova I.E., Shagimuratov I.I., Martynenko O.V.
Ionospheric total electron content variations observed before earthquakes: Possible physical mechanism and modeling
Some experiments have been carried out by phase association and infrasonic sources location using the Apatity infrasound array and Finnish-Swedish acoustic network. Several events from the area of Plesetsk spaceport have been detected and located. The analysis of variation of backazimuth estimations has been done basing on signals from repeating military explosion in Northern Finland. Estimations of the location accuracy for the explosions have been obtained. It has been confirmed that cause-effect relation exists between facts of presence or absence of infrasonic wave first arrivals and weather conditions.
(in English, стр.8, fig. 6, tables. 0, ref 29, Adobe PDF, Adobe PDF 0 Kb)
Vol. 12 (2009 year), No. 2
Zubova Yu.V., Namgaladze A.A.
The vibrationally excited molecular nitrogen effects by numarical modelling of the ionospheric F2-layer behaviour during major magnetic storms
The GPS derived TEC disturbances before earthquakes were discovered in the last years using global and regional TEC maps, TEC measurements over individual stations as well as measurements along individual GPS satellite passes. For strong mid-latitudinal earthquakes the seismo-ionospheric anomalies look like local TEC enhancements or decreases located in the vicinity of the forthcoming earthquake epicenter. Such structures are generated in the ionosphere for several days prior to the main shock. The amplitude of plasma modification reaches the value of 30-90 % relative to the non-disturbed level. The zone of the anomaly maximum manifestation extends larger than 1500 km in latitude and 3500-4000 km in longitude. In case of strong low-latitudinal earthquakes there are effects related with the modification of the equatorial F2-region anomaly: deepening or filling of the ionospheric electron density trough over the magnetic equator. The possible physical mechanism which can cause such anomalies has been proposed. We consider that the most probable reason of the NmF2 and TEC disturbances observed before the earthquakes is the vertical drift of the F2-region ionospheric plasma under the influence of the zonal electric field of seismic origin. To check this hypothesis, the model calculations have been carried out with the use of the UAM (Upper Atmosphere Model) – the global numerical model of the Earth’s upper atmosphere. The electric potential distribution at the near-epicenter region boundary required for the electric field maintenance has been proposed. The upper atmosphere state, presumably foregone a strong earthquake, has been modeled by means of switching-on of additional sources of the electric field in the UAM electric potential equation which was solved numerically jointly with all other UAM equations (continuity, momentum and heat balance) for neutral and ionized gases. The efficiency of the proposed mechanism has been investigated by means of model calculations of the ionosphere response to the action of zonal electric field produced by seismogenic sources located at the middle and low latitudes. The results of the corresponding numerical model calculations of the electric field and its effects in the ionospheric F2-layer and plasmasphere have been presented. They have revealed a fine agreement with TEC anomalies observed before strong earthquakes at the middle and low latitudes both in spatial scales and in amplitude characteristics.
(in Russian, стр.12, fig. 14, tables. 1, ref 24, Adobe PDF, Adobe PDF 0 Kb)
Vol. 13 (2010 year), No. 4
Knyazeva M.A., Zubova Yu.V., Namgaladze A.A.
Numerical modelling of the Weddell Sea Anomaly in behaviour of the ionospheric F2-region
The morphology and mechanism of the Weddell Sea Anomaly (WSA) forming has been investigated by using the global numerical model of the Upper Atmosphere Model and empirical model of the ionosphere IRI-2001. It has been shown that both models reproduce WSA in the summer southern hemisphere in longitudinal sector 255-315?E. It has been found that the analogous WSA longitudinal variation of the electron density takes place in the summer northern hemisphere in longitudinal sector 75-135?E. It has been shown that both phenomena are caused by the non-coincidence of the geomagnetic and geodetic axes which produces the difference in vertical velocities of the ion transfer by the thermospheric wind action in the western and eastern longitudinal sectors.
(in Russian, стр.10, fig. 6, tables. 0, ref 32, Adobe PDF, Adobe PDF 0 Kb)
Vol. 14 (2011 year), No. 3
Botova M.G., Martynenko O.V., Namgaladze A.A.
Numerical modeling of the ion temperature influence
The formation of three-dimensional structure of the "plasmasphere – ionosphere" system under the influence of ionization / recombination, charge exchange reactions and field-aligned (along the geomagnetic field lines) diffusion of ions O+ and H+ has been investigated by the numerical simulation method using the global upper atmosphere model (UAM). A few large-scale structural features: 3 night-time ionospheric electron density maxima – sub-auroral, mid-latitudinal and near-equatorial, and corresponding peaks of n(O+) in the outer plasmasphere and n(H+) in the mid-latitudinal plasmasphere have been obtained. The geometry of the geomagnetic field and the spatial non-homogeneity of the ion temperature give a determinative contribution to the formation of these features.
(in Russian, стр.6, fig. 1, tables. 0, ref 17, Adobe PDF, Adobe PDF 0 Kb)
Vol. 15 (2012 year), No. 2
Karpov M.I., Zolotov O.V., Namgaladze A.A.
Modeling of the ionosphere response on the earthquake preparation
Seismo-ionosphere coupling processes have been investigated considering the GPS observed anomalous ionospheric Total Electron Content (TEC) variations before strong earthquakes as their precursors. The numerical simulations' results of the TEC response on the vertical electric currents flowing between the Earth and ionosphere during the earthquake (EQ) preparation time have been performed. Model experiments have been carried out using the Upper Atmosphere Model. The following currents' parameters were varied in: (i) direction (to or from the ionosphere); (ii) latitudinal zone of the sources' (EQ epicenters) location; (iii) currents' configuration: (1) grid nodes with "straight" currents were surrounded by "border" grid points with currents of opposite direction ("return" currents); (2) the "return" currents were spread out over the globe; (3) without "return" currents. Numerical simulations have shown that electric currents with density of 4?10-8 A/m2 over the area of about 200 km in longitude and 2500 km in latitude produce both positive and negative TEC disturbances with magnitude up to 35 % in agreement with GPS TEC observations before EQs.
(in English, стр.6, fig. 4, tables. 0, ref 27, Adobe PDF, Adobe PDF 0 Kb)
Vol. 15 (2012 year), No. 2
Romanovskaya Yu.V., Namgaladze A.A., Zolotov O.V., Starikova N.A., Lopatiy V.Z.
Searching for seismo-ionospheric earthquakes precursors: Total electron content disturbances before 2005-2006 seismic events
During earthquakes preparation periods significant disturbances in the ionospheric plasma density are often observed. These anomalies are caused by lithosphere-atmosphere-ionosphere interaction, particularly by the seismic electric field penetrating from the ground surface into the ionosphere. The seismic electric field produces electromagnetic ЕВ drift changing plasma density over the epicenter region and magnetically conjugated area. The paper is devoted to analysis of regular Global Positioning System observations and revelation of seismo-ionospheric precursors of earthquakes in Total Electron Content (TEC) of the ionosphere. Global and regional relative TEC disturbances maps (%) have been plotted for 2005-2006 M6, D<60 km seismic events and analyzed in order to determine general features of precursors. The obtained results agree with the recent published case-study investigations.
(in English, стр.5, fig. 2, tables. 0, ref 29, Adobe PDF, Adobe PDF 0 Kb)
Vol. 15 (2012 year), No. 3
Zolotov O.V., Namgaladze A.A., Prokhorov B.E.
Total electron content disturbances prior to Great Tohoku March 11, 2011 and October 23, 2011 Turkey Van earthquakes and their physical interpretation
This paper discusses the GPS (Global Positioning System) observed TEC (Total Electron Content) variations prior to the M 9.0 Great Tohoku (Japan, Sendai) March 11, 2011 and M 7.1 Oct. 23, 2011 Turkey Van earthquakes as possible seismo-ionosphere precursors. We have formulated a set of the TEC phenomenological features often reported as precursors to strong earthquakes based on our experience and publications' analysis. This feature-set has been applied to the relative TEC deviations for time intervals March 08-11, 2011 and Oct. 20-23, 2011 preceding M 9.0 Great Tohoku (Japan) March 11 and Turkey Van Oct. 23 earthquakes, respectively. In both cases there have been revealed strong local long-living (of about several hours) TEC disturbances at the near-epicenter and magnetically conjugated areas. These disturbances may be treated as seismo-ionospheric precursors. The physical mechanism for the observed TEC structures for these two as well as for other cases of recent strong seismic events has been proposed. The anomalies have been interpreted and explained on the base of this physical mechanism from the origin hypothesis point of view in terms of electromagnetic lithosphere-ionosphere coupling.
(in English, стр.12, fig. 3, tables. 0, ref 63, Adobe PDF, Adobe PDF 0 Kb)
Vol. 15 (2012 year), No. 3
Karpov M.I., Namgaladze A.A., Zolotov O.V.
Three-dimensional structure of the seismo-electromagnetic ionospheric electron density disturbances
The paper presents the three-dimensional structure of the ionospheric electron density disturbances triggered by the vertical electric currents flowing between the Earth and ionosphere over the faults before the strong earthquakes. The results were obtained using the global numerical Earth's Upper Atmosphere Model (UAM). The vertical electric currents flowing between the Earth and ionosphere over the faults were used as lower boundary conditions for the UAM electric potential equation. The UAM calculated 3D structure of the ionospheric electron density disturbances demonstrates an importance of all three ionospheric plasma drift movements – vertical, meridional and zonal but not only vertical one.
(in English, стр.9, fig. 9, tables. 0, ref 26, Adobe PDF, Adobe PDF 0 Kb)
Vol. 15 (2012 year), No. 3
Knyazeva M.A., Romanovskaya Yu.V., Namgaladze A.A.
Numerical modeling of the electron density enhancements in the night-time ionospheric F2-layer
The middle-latitude enhanced electron density regions (EEDRs) in the night-time ionospheric F2-layer have been investigated using the global numerical Upper Atmosphere Model (UAM) and the empirical ionospheric model IRI-2001. The mechanism of formation, seasonal and latitudinal-longitudinal variations of the EEDRs has been studied. It has been shown that two types of the EEDRs exist on the geomagnetic foF2 maps: 1) winter type with maxima in the latitudinal and diurnal foF2 variations and 2) summer type with the maximum in the latitudinal variation only. Formation of both types of the EEDRs is explained by the corresponding seasonal variations of the thermospheric wind. The physical mechanism of the EEDRs forming is based on the joint action of the plasma flows from the plasmasphere and the neutral wind inducing transportation of the ionospheric plasma along the geomagnetic field lines. The Weddell Sea Anomaly and the analogous phenomenon observed in the Northern Hemisphere have been explained.
(in English, стр.14, fig. 7, tables. 0, ref 56, Adobe PDF, Adobe PDF 0 Kb)