@article{ZolotovProkhorovNamgaladzeetal.2011, author = {Zolotov, O. V. and Prokhorov, Boris E. and Namgaladze, Alexander A. and Martynenko, O. V.}, title = {Variations in the total electron content of the ionosphere during preparation of earthquakes}, series = {Russian journal of physical chemistry : B, Focus on physics}, volume = {5}, journal = {Russian journal of physical chemistry : B, Focus on physics}, number = {3}, publisher = {Pleiades Publ.}, address = {New York}, issn = {1990-7931}, doi = {10.1134/S1990793111030146}, pages = {435 -- 438}, year = {2011}, abstract = {The morphological features in the deviations of the total electron content (TEC) of the ionosphere from the background undisturbed state as possible precursors of the earthquake of January 12, 2010 (21:53 UT (16:53 LT), 18.46A degrees N, 72.5A degrees W, 7.0 M) in Haiti are analyzed. To identify these features, global and regional differential TEC maps based on global 2-h TEC maps provided by NASA in the IONEX format were plotted. For the considered earthquake, long-lived disturbances, presumably of seismic origin, were localized in the near-epicenter area and were accompanied by similar effects in the magnetoconjugate region. Both decreases and increases in the local TEC over the period from 22 UT of January 10 to 08 UT of January 12, 2010 were observed. The horizontal dimensions of the anomalies were similar to 40A degrees in longitude and similar to 20A degrees in latitude, with the magnitude of TEC disturbances reaching similar to 40\% relative to the background near the epicenter and more than 50\% in the magnetoconjugate area. No significant geomagnetic disturbances within January 1-12, 2010 were observed, i.e., the detected TEC anomalies were manifestations of interplay between processes in the lithosphere-atmosphere-ionosphere system.}, language = {en} } @article{ProkhorovFoersterHeetal.2014, author = {Prokhorov, Boris E. and Foerster, M. and He, M. and Namgaladze, Alexander A. and Holschneider, Matthias}, title = {Using MFACE as input in the UAM to specify the MIT dynamics}, series = {Journal of geophysical research : Space physics}, volume = {119}, journal = {Journal of geophysical research : Space physics}, number = {8}, publisher = {American Geophysical Union}, address = {Washington}, issn = {2169-9380}, doi = {10.1002/2014JA019981}, pages = {11}, year = {2014}, abstract = {The magnetosphere-ionosphere-thermosphere (MIT) dynamic system significantly depends on the highly variable solar wind conditions, in particular, on changes of the strength and orientation of the interplanetary magnetic field (IMF). The solar wind and IMF interactions with the magnetosphere drive the MIT system via the magnetospheric field-aligned currents (FACs). The global modeling helps us to understand the physical background of this complex system. With the present study, we test the recently developed high-resolution empirical model of field-aligned currents MFACE (a high-resolution Model of Field-Aligned Currents through Empirical orthogonal functions analysis). These FAC distributions were used as input of the time-dependent, fully self-consistent global Upper Atmosphere Model (UAM) for different seasons and various solar wind and IMF conditions. The modeling results for neutral mass density and thermospheric wind are directly compared with the CHAMP satellite measurements. In addition, we perform comparisons with the global empirical models: the thermospheric wind model (HWM07) and the atmosphere density model (Naval Research Laboratory Mass Spectrometer and Incoherent Scatter Extended 2000). The theoretical model shows a good agreement with the satellite observations and an improved behavior compared with the empirical models at high latitudes. Using the MFACE model as input parameter of the UAM model, we obtain a realistic distribution of the upper atmosphere parameters for the Northern and Southern Hemispheres during stable IMF orientation as well as during dynamic situations. This variant of the UAM can therefore be used for modeling the MIT system and space weather predictions.}, language = {en} } @article{ZolotovNamgaladzeProkhorov2013, author = {Zolotov, Oleg V. and Namgaladze, Alexander A. and Prokhorov, Boris E.}, title = {Specific features of ionospheric total electron content variations in the periods of preparation of the earthquakes on March 11, 2011 (Japan) and October 23, 2011 (Turkey)}, series = {Russian journal of physical chemistry : B, Focus on physics}, volume = {7}, journal = {Russian journal of physical chemistry : B, Focus on physics}, number = {5}, publisher = {Pleiades Publ.}, address = {New York}, issn = {1990-7931}, doi = {10.1134/S1990793113050266}, pages = {599 -- 605}, year = {2013}, abstract = {The main morphological features of variations of the total electron content (TEC) of the ionosphere before the earthquakes on March 11, 2011 (Japan) and October 23, 2011 (Turkey) are examined. The revealed features are compared to those of ionospheric TEC disturbances observed prior to several other large seismic events, as well as to those included in a list of the most frequently observed ionospheric TEC disturbances interpreted as possible ionospheric precursors of earthquakes. It is shown that, in the periods of preparation of the earthquakes under consideration, on March 8-11 and October 20-23, abnormal ionospheric TEC disturbances were observed as long-lived structures in a near-epicentral region and in the region magnetically conjugated to it.}, language = {en} } @article{NamgaladzeZolotovProkhorov2013, author = {Namgaladze, Alexander A. and Zolotov, O. V. and Prokhorov, Boris E.}, title = {Numerical simulation of the variations in the total electron content of the ionosphere observed before the Haiti earthquake of January 12, 2010}, series = {Geomagnetism and aeronomy}, volume = {53}, journal = {Geomagnetism and aeronomy}, number = {4}, publisher = {Pleiades Publ.}, address = {New York}, issn = {0016-7932}, doi = {10.1134/S0016793213030122}, pages = {522 -- 528}, year = {2013}, abstract = {We present the results of a study of the abnormal variations in the total electron content (TEC) of the ionosphere observed before the earthquake of January 12, 2010, in Haiti. Global and regional maps of TEC relative (\%) deviations from the quite background state are built for January 9-12, 2010. Using the UAM (Upper Atmosphere Model) global numerical model of the upper atmosphere of the Earth, the variations in the electric potential in the ionosphere and TEC are calculated using external seismic current above faults between the Earth and the ionosphere as a lower boundary condition. The numerical simulation results are compared with observations. It is shown that the simulated variations in the TEC at a specified current density of about 1 x 10(-8) A/m(2) on an area of 200 km (latitude) x 4000 km (longitude) above the focus represent all main features of the observations: prevalence of increased TEC values (positive disturbances), neighboring negative disturbances of lower magnitudes, localization, magnetic conjugacy of high-intensity effects in the Southern Hemisphere, and disappearance of disturbances around midday. Methodological recommendations are given to reveal variations in the TEC related to the preparation of seismic events.}, language = {en} } @article{BotovaNamgaladzeProkhorov2013, author = {Botova, M. G. and Namgaladze, Alexander A. and Prokhorov, Boris E.}, title = {Modeling of variations of the peak F2 layer electron density and total electron content during the recovery period after the magnetic storm of April 15-20, 2002}, series = {Russian journal of physical chemistry : B, Focus on physics}, volume = {7}, journal = {Russian journal of physical chemistry : B, Focus on physics}, number = {5}, publisher = {Pleiades Publ.}, address = {New York}, issn = {1990-7931}, doi = {10.1134/S1990793113050151}, pages = {606 -- 610}, year = {2013}, abstract = {The results of numerical modeling by using the global upper atmosphere model of the Earth (UAM) for reproducing the peak F2 layer electron density (N (m) F2) and total electron content (TEC) during recovery period after the magnetic storm of the April 15-20, 2002 are discussed. According to the simulations, the time it takes to reach a stationary regime of N (m) F2 and TEC diurnal variations is 24 hours, much shorter then the plasmasphere refilling time. The results are compared with the predictions of the IRI-2007 empirical model and GPS data on the TEC and found in good quantitative agreement for the latitudinal variations of N (m) F2 and TEC for daytime conditions in the southern hemisphere. The worst agreement occurs in the region of the main ionospheric trough.}, language = {en} } @article{ProkhorovFoersterLesuretal.2018, author = {Prokhorov, Boris E. and F{\"o}rster, Matthias and Lesur, Vincent and Namgaladze, Alexander A. and Holschneider, Matthias and Stolle, Claudia}, title = {Modeling of the ionospheric current system and calculating its}, series = {Magnetic Fields in the Solar System: Planets, Moons and Solar Wind Interactions}, volume = {448}, journal = {Magnetic Fields in the Solar System: Planets, Moons and Solar Wind Interactions}, publisher = {Springer}, address = {Dordrecht}, isbn = {978-3-319-64292-5}, issn = {0067-0057}, doi = {10.1007/978-3-319-64292-5_10}, pages = {263 -- 292}, year = {2018}, abstract = {The additional magnetic field produced by the ionospheric current system is a part of the Earth's magnetic field. This current system is a highly variable part of a global electric circuit. The solar wind and interplanetary magnetic field (IMF) interaction with the Earth's magnetosphere is the external driver for the global electric circuit in the ionosphere. The energy is transferred via the field-aligned currents (FACs) to the Earth's ionosphere. The interactions between the neutral and charged particles in the ionosphere lead to the so-called thermospheric neutral wind dynamo which represents the second important driver for the global current system. Both processes are components of the magnetosphere-ionosphere-thermosphere (MIT) system, which depends on solar and geomagnetic conditions, and have significant seasonal and UT variations. The modeling of the global dynamic Earth's ionospheric current system is the first aim of this investigation. For our study, we use the Potsdam version of the Upper Atmosphere Model (UAM-P). The UAM is a first-principle, time-dependent, and fully self-consistent numerical global model. The model includes the thermosphere, ionosphere, plasmasphere, and inner magnetosphere as well as the electrodynamics of the coupled MIT system for the altitudinal range from 80 (60) km up to the 15 Earth radii. The UAM-P differs from the UAM by a new electric field block. For this study, the lower latitudinal and equatorial electrodynamics of the UAM-P model was improved. The calculation of the ionospheric current system's contribution to the Earth's magnetic field is the second aim of this study. We present the method, which allows computing the additional magnetic field inside and outside the current layer as generated by the space current density distribution using the Biot-Savart law. Additionally, we perform a comparison of the additional magnetic field calculation using 2D (equivalent currents) and 3D current distribution.}, language = {en} } @article{FoersterNamgaladzeDoroninaetal.2011, author = {F{\"o}rster, M. and Namgaladze, Alexander A. and Doronina, E. N. and Prokhorov, Boris E.}, title = {High-latitude thermospheric winds: Satellite data and model calculations}, series = {Russian journal of physical chemistry : B, Focus on physics}, volume = {5}, journal = {Russian journal of physical chemistry : B, Focus on physics}, number = {3}, publisher = {Pleiades Publ.}, address = {New York}, issn = {1990-7931}, doi = {10.1134/S1990793111030043}, pages = {439 -- 446}, year = {2011}, abstract = {The thermospheric crosswind velocities at an altitude of 400 km measured by an accelerometer on board of the CHAMP satellite are compared with the results of model calculations performed using the Upper Atmosphere Model (UAM). The results of measurements averaged over the year in 2003 reveal a two-vortex structure of high-latitude winds corresponding to magnetospheric-ionospheric convection of ions in the F2 ionosphere region. A similar picture with similar speed values was obtained in model calculations. A comparison of the crosswind speed obtained in individual measurements on October 28, 2003 with the corresponding model values revealed close agreement between them in some flights and differences in others. Taking into account the dependence of convection electric field on the B (y) component of interplanetary magnetic field sometimes improved agreement between thermospheric crosswind speeds obtained in model calculations and measured using the satellite.}, language = {en} }