Results are presented from comparing an analytical study of the radial distribution of magnetohydrodynamic disturbances of magnetic field components in the body of a model solar wind magnetic cloud to data on a real cloud recorded on a spacecraft. An analytical–numerical solution for disturbances was found using a cylindrical coordinate system for a cloud represented by a force-free cylindrical tube with a helical magnetic field. The general idea of the radial distribution of the magnetic field components in the body of the magnetic cloud is consistent with the registered parameters of magnetic field disturbances on patrolling spacecraft, as is confirmed by an objective correlation analysis. Joint post-processing of the count results and real data enhances the consistency, testifying to the adequacy of the magnetohydrodynamic approach to analyzing oscillations in the model body of the magnetic cloud.

A neural network forecast of substorms caused by the impact of solar wind plasma flows on the Earth’s magnetosphere has been performed. For this, recurrent neural network models were created based on physical cause-and-effect relationships of the dynamics of high-latitude geomagnetic activity (according to the AL index) with the parameters of the interplanetary magnetic field (IMF) and solar wind plasma (SWP). Two parameters are used as input sequences: the bz-component of the IMF and the integral parameter Σ[NV 2], taking into account the prehistory of the process of pumping the kinetic energy of the solar wind into the magnetosphere, where N and V are the plasma density and solar wind velocity, respectively. The forecast of the AL index according to SWP and IMF for 10 min, etc. with 10 min discreteness individually by an individual artificial neural network (ANN) for each point corresponding to the dynamics of the AL index was completed. This means that the prediction of a continuous series of values AL index is achieved by a parallel running of the ANN package. The number of ANNs in the package is determined by the duty cycle of the required predictive series of the AL index, while taking 90 min of the history of input parameters in each of the networks into account provides a prediction of the values AL index with an accuracy of 80

Images are created of the causal relationship between substorm activity and the characteristics of such large-scale solar fluxes as magnetic clouds interacting with the Earth’s magnetosphere. An artificial neural network of the Kohonen layer type is used to classify these images. The results from classification identify selected classes of substorms with perturbations in parameters of the solar wind and interplanetary magnetic field that are typical of structural elements of magnetic clouds.

В исследовании рассмотрены особенности генерации высокоширотных геомагнитных возмущений, вызываемых оболочками магнитных облаков (МО) солнечного ветра представляющих собой горячую и плотную турбулентную плазму с сильными флуктуациями компонент межпланетного магнитного поля. Для этих целей выполнены нейросетевые классификационные эксперименты по сопоставлению динамики параметров оболочек магнитных облаков с динамикой аврорального AL-индекса еще до развития глобального геомагнитного возмущения. Результаты, полученные искусственным интеллектом, согласуются с физическими представлениями о процессах развития высокоширотной геомагнитной активности под действием турбулентной среды оболочек магнитных облаков на земную магнитосферу.

Simultaneous disturbances of the total electron content and the horizontal component of geomagnetic field in the range of Pc6 are registered during periods of magnetospheric substorms. Such disturbances arise in intervals of interaction between Earth’s magnetosphere and the turbulent sheath of magnetic clouds. Wavelet analysis of disturbances in the interplanetary magnetic field and the velocity and density of solar wind plasma testify to the existence of oscillations with similar periods in the interplanetary medium.

A Kohonen artificial neural network (ANN) was used to classify patterns of causal relationships between the level of geomagnetic activity in the auroral zone and plasma and magnetic field parameters in the body of an interplanetary magnetic cloud (IMO). Terrestrial and satellite observations during 33rd interplanetary magnetic clouds recorded from 1998 to 2012 are examined in detail. Experiments with the ANN during its fast training show that substorm discrimination by their intensity by three classes plus a "collector" for collecting atypical events is optimal for the study. An analysis of the classification result studies showed that each selected class of substorms corresponds to a specific set of perturbations of the plasma parameters and the magnetic field of the IMO. Using the integral characteristics of the plasma and the IMF components as input parameters of the ANN allowed us to detect the levels of the expected intensity of the AL index with an accuracy of up to 70%. The created ANNs can be used to restore the AL index both during periods of isolated magnetospheric substorms and during periods of a series of continuous successive substorms, one after another.

Впериоды магнитосферных суббурь зарегистрированы одновременные возмущения полного электронного содержания и горизонтальной компоненты геомагнитного поля в диапазоне периодов Рс6, возникающие в интервалы взаимодействия магнитосферы Земли с турбулентной оболочкой магнитных облаков. Вейвлет анализ возмущений межпланетного магнитного поля, скорости и плотности плазмы солнечного ветра свидетельствует о существовании в межпланетной среде колебаний с такими же периодами.

The efficiency of the previously developed algorithm for predicting extreme solar flares from their geomagnetic precursors has been tested on the example of a series of class X flares recorded on September 6, 2017. Over the past few years, these events of the solar flare activity are seen as the most intense. The algorithm consists in comparing the total histograms of the normalized number of synchronization moments for oscillations of long-period pulsations in the horizontal component of the geomagnetic field with extreme solar flare events in the intervals preceding them. The result of the algorithm is that extrema of histograms were detected a few days before the development of intense solar flares and can be considered as markers of the expected extreme flare activity. The study confirms the possibility of using the previously proposed algorithm for a short-term forecast of solar flare activity.

We propose a method for determining location and orientation of extended solar sources of magnetic clouds, using coronagraph data and SOHO EIT/MDI images of the photosphere. To estimate the probability of formation of magnetic clouds, we use a simple cylindrical force-free model. We have established that more extended sources and those having a slight inclination to the solar equator and located on the solar limb as compared to those that are nonextended and strongly inclined can generate expanding clouds, which with high probability can reach the magnetosphere like clouds from a source near the zero meridian and low latitudes. We determine the relationship between extreme values of substorm activity and parameters of solar sources under study during the impact of magnetic clouds on Earth’s magnetosphere from the AL index. We note that there are no substorms associated with extended sources outside the heliolatitude range ~5–20°. The established relationship between solar source coordinates and geomagnetic activity of the magnetic cloud sheath and body are consistent with the most probable distribution of magnetoactive regions over the solar disk.

The paper draws attention to the complex structure of the fast magnetic clouds of the solar wind, which, in addition to the actual cloud body, contain a turbulent transition layer (cloud sheath) with a large and irregular magnetic field following the shock wave. The orientation of the plane of the magnetic-cloud shock wave with respect to the interplanetary magnetic field modified by the shock wave propagating in the solar wind for 33 cases of the registration of fast magnetic clouds has been calculated. The dependence of the substorm activity in the auroral zone on the level of turbulent processes occurring in the sheath of magnetic clouds has been studied. It was taken into account that the turbulent phenomena in the sheath are largely determined by the orientation of the shock-wave plane with respect to the interplanetary magnetic field. It is shown that the level of magnetic activity in the auroral zone, which is characterized by the integral AL index, increases with a decrease in the angle between the direction normal to the shock-wave front and the vector of the interplanetary magnetic field. Thus, the most geoeffective are magnetic clouds with a quasi-parallel shock wave, and the least geoeffective are those with a quasi-perpendicular shock wave. It was concluded that the intensity of turbulent processes in the cloud sheath increases with a decrease in the magnetic field penetrating the sheath, which plays a stabilizing role for turbulent magnetohydrodynamic perturbations.

Comparison of wavelet spectrum (skeletons) local maxima for disturbed components of solar plasma flow parameters and geomagnetic field disturbances recorded along the meridional station chain during geomagnetic storm intervals is performed in the range of magnetohydrodynamic (MHD) waves. An algorithm for quantitative evaluation of analyzed skeletons consistency has been developed. It has been used to demonstrate the possibility of the type of solar wind plasma flow elaboration on unique spectral signs of Solar wind speed disturbances, density and interplanetary magnetic field. It is shown that the energy spectrum of oscillations for these parameters reflects the internal structure of the corresponding plasma formation. The skeletons application to the analysis of the interplanetary space main parameters made it possible to estimate the magnetosphere reaction time in geomagnetic field horizontal component oscillations at different latitudes on the disturbance. As a result, the distributed magnetosphere reaction over latitude was determined in the form of geomagnetic field oscillations on the disturbed solar flow parameters. It is shown that the dynamics of the components of the solar wind parameters disturbance spectra corresponding to plasma flows manifest themselves in the MHD spectra of high-latitude stations magnetograms and can be used as a diagnostic tool. Â

The phenomena accompanying the event of synchronous night-time ionospheric and geomagnetic disturbances, marked in globally magnetospecific quiet-time on the base of the mid-latitude Kazan station minute data, are analyzed. The dynamic and wavelet spectra comparison for studied disturbances showed coinciding features of the simultaneous disturbances for layer F2 critical frequency and H, D, Z geomagnetic field components. Therefore it was possible to assume their magnetosonic nature and establish the characteristic periods of observed magnetosonic ULF disturbances in the range of 35-50 minutes. The spatial analysis of noted magnetosonic disturbances with use of geomagnetic data obtained at stations located at different latitudes and longitudes toward to Kazan station demonstrated the isotropy of founded magnetosonic waves. This allows classifying them as fast magnetosonic disturbances. It is shown that the studied event occurs under substorm development conditions. The causes establishment of intramagnetospheric magnetohydrodynamic (MHD) disturbance is an important goal of solar-terrestrial physics. The appearance of magnetosound disturbances in the magnetosphere-ionospheric medium is commonly associated with development of geomagnetic storm. MHD disturbances in the magnetosphere and ionospheric conductive layers can also be associated however with other high-energy processes. In studies [Barkhatova et al., 2009; Barkhatova et al., 2015], for example, magnetosound type waves, generated by an eastward electrojet and earthquakes of large magnitude were detected. At the same time in addition to geomagnetic field disturbances, synchronous disturbances in ionospheric conductive layer F2 in the ULF range were observed. The present study is devoted to the analysis of phenomena accompanying the event of synchronous night time ionospheric and geomagnetic disturbances, detected in the globally magneto-quiet time at the midvertical sounding data and data of geomagnetic field H, D, and Z components with a minute resolution for the interval September 1-4, 2014. The coinciding features of F2 layer critical frequency and the geomagnetic field components simultaneous disturbances as a result of dynamic spectra and wavelet patterns comparison of studied disturbance for September 3, 2014 were found. For other days (1, 2 and 4 September) in the night time region (+ 3 GMT) there is no pronounced ionospheric disturbance. Fig. 1 shows the critical frequency foF2 and the geomagnetic field H component wavelet spectra for Kazan station, received for September 3, 2014 during the night time interval (00.00 to 02.00 UT). The black arrows show the maxima coincidence of ionospheric and geomagnetic field H component disturbances for the interval 01.17 01.55 UT. The best coincidence of considered disturbances was noted for periods from 15 to 30 minutes. The fact of simultaneous disturbances for foF2 and the geomagnetic field components coincide allow us to assume their magnetosound nature. The question of relation for considered disturbances to SMS (slow magnetosound), more likely associated to geomagnetic field force line, or to an isotropic FMS (fast magnetosound) type can be solved by spatial analysis of disturbance wavelet spectra received at stations with different latitudes and longitudes from Kazan. The data of 51.87 E), Hel (54.61 N, 18.82 E), San Fernando (36.67 N, 5.50 W). The coincidence of spectral maxima for Kazan station critical frequency and geomagnetic field H component at the magneto-conjugated observatory Port Alfred (southern hemisphere) for the analyzed frequency range is established for the studied time interval. This indicates the connection of studied wave phenomenon to the corresponding geomagnetic force line. The comparison of the disturbance spectral features for the critical frequency over Kazan with disturbances of geomagnetic field H, D components at other stations located in a large latitudinal-longitude region also showed cases of analyzed spectral features coincidence. Such isotropic behavior for studied magnetosound waves makes it possible to classify them as fast magnetosound disturbances. The search for a possible source of considered night time mid-latitude synchronous ionospheric and geomagnetic disturbances required the study of outer magnetospheric processes. During the case of foF2 disturbances in Kazan, disturbances of the interplanetary magnetic field Bz component (Bz IMF) were detected in the same frequency range. So it was established that the long-period oscillations of Bz IMF find their manifestation in the ionosphere and geomagnetic field components. Fig. 2 shows the wavelet spectra of the foF2 critical frequency at Kazan station (upper panel) and Bz IMF component for the considered time interval. Synchronization of geomagnetic and ionospheric disturbances on the substorm process background 98 A study of time behavior for the Solar wind concentration shows that in the time period up to 00.45 UT (+3 GMT Kazan) its higher values are observed with a further decrease and reaching the minimum value at 01.00 UT. For the interval 01.00 02.00 UT, there is a general increase in the Solar wind velocity, which persists throughout the interval. Figure 1. Wavelet spectra of F2 layer critical frequency (the first panel from the top) and geomagnetic field H component (second panel) for September 3, 2014. The black arrows indicate a correspondence between the spectra maximums for foF2 and the H component disturbances. Figure 2. Wavelet spectra of the ionospheric layer F2 critical frequency and interplanetary magnetic field Bz component disturbances for September 3, 2014. The arrows indicate areas of the spectral singularities coincidence for foF2 critical frequency and IMF Bz component. O.M. Barkhatova et al. 99 In addition, during ~ 01.00 UT, the values of IMF Bz component change from small negative to positive values. Such situation, according to [Barkhatov et al., 2017; Morley and Freeman, 2007], correspond to the substorm development. Note that the considered time interval corresponds to the night-time magnetosphere sector, within the westward electrojet (AL) is localized. Its dynamic shows that during this time there really is a bay-like disturbance preceded a non-disturbed period (AL ~ -20 nT). Fig. 3 shows the dynamics of the Solar wind parameters and the AL index. Black vertical lines indicate the coincidence of foF2 and geomagnetic field H component spectral features at Kazan station. The performed results demonstrate the possibility of synchronous ionospheric and geomagnetic disturbances existence in the class of Pi3 pulsations (periods of 15-30 min) at medium latitudes for local nighttime in the global geomagnetic non-disturbed conditions. The magnetosound nature of observed disturbances is demonstrated by comparing of foF2 critical frequency over the Kazan station and geomagnetic field component spectral patterns over a large spatial region including high, middle and low latitudes. The revealed magnetosound disturbances can be generated by the instability of westward electrojet. At the same time, these electrojet participates in substorm process as an element of a large-scale three-dimensional current system a substorm current wedge. During the substorm development, the extended magnetic force lines of geomagnetic tail are subjected to ULF vibration by disturbed magnetized Solar wind. It makes possible to explain such low frequencies of observed disturbances in comparison with resonant MHD oscillations under quiet conditions. Thus, the noted synchronization of ionospheric and magnetic disturbances gives reason for believing that detected disturbances have a magnetosound nature and are associated with substorm activity. Acknowledgements. -05-35-00084 and the Ministry of for provided Kazan ionospheric vertical sounding data. Figure 3. Interplanetary magnetic field component Bx, By, Bz plots (left panel), Solar wind velocity and concentration (right panel) for September 3, 2014. Vertical black lines indicate the coincidence of foF2 and H component spectral features at Kazan station.

The phenomena which accompany synchronization of night-time ionospheric and geomagnetic disturbances in an ULF range with periods 35–50 min near the mid-latitude station Kazan during a global magnetically quiet period have been analyzed. The comparison between dynamic spectra and wavelet patterns of these disturbances has revealed that spectral features of simultaneous disturbances of the F2-layer critical frequency and H, D, Z geomagnetic field components are similar. By studying spectral features of the F2-layer critical frequency over Kazan and disturbances of the H and D geomagnetic field components at magnetic stations which differ from Kazan station in longitude and latitude, we have established that the disturbances considered belong to the class of fast magnetosonic waves. The analysis of solar wind parameters, interplanetary magnetic field (IMF), and values of the auroral index AL in the period under study has shown that this event is associated with IMF Bz component disturbances and occurs during substorm development.

The pattern of ionospheric activity along the meridional and latitudinal directions in the middle latitudes was analyzed based on the previously suggested IAI index. The contribution of the solar and geophysical factors that largely control the midlatitude ionosphere and the general level of the ionospheric disturbance were established. Changes in the ionospheric activity traced along a meridian from lower to higher latitudes in the interval from 35° to 50° N were quantified. Based on the obtained results, a method is suggested for calculating a correction of the IAI index, which makes it possible to estimate IAI at any desired latitude from the values of this index at a particular station. A neural network approach is developed for prompt diagnosis and forecasting of the state of the midlatitude ionosphere in terms of the IAI index from the level of the solar-geophysical activity. The optimal configuration of the neural network and the most efficient input parameters, which provide the maximum (75%) efficiency of the neural network forecasts of the IAI index, are determined.

Magnetogravity activity during the preparation of four strong (M > 6.5) earthquake with epicenters at medium (35–40° N) and low (10° S–10° N) latitudes is detected. For this purpose a comparison of simultaneous disturbances at dynamic spectra of ionospheric layers Es, E, F2 critical frequencies and geomagnetic field X, Y, Z components was performed. It was found that the greatest number of magnetogravity events noted in epicenters vicinity takes place at two days before the considered earthquakes. Evaluation of dynamic spectra intensity level which was obtained by data from magnetic stations located around the epicenter, allows to identify the magnetogravity waves (MGW) propagation direction with least damping. In most cases they coincide with geomagnetic field direction. Attention is paid to ionospheric wind influence for low-frequency MGW mode.

Synchronous disturbances of ionospheric (layers F2, E, and Es) electron density and the geomagnetic field components during the intervals of strong earthquakes (exceeding 6.5 on the Richter magnitude scale) (8 January 2006 and 17 July 2006 off the west coast of Indonesia) have been detected. These disturbances are supposed to be related to the formation of magnetogravity waves (MGWs) during the development of high energy geophysical events. The enhancement of MGW activity takes place two days before and after the quake. On the day of the event MGWs are not registered except for the passage of acoustic-gravity waves. The existence of MGWs is analytically confirmed by the dispersion analysis under conditions of the horizontal geomagnetic field (near-equatorial regions) and the finite ionospheric conductivity.

The possibility of magnetogravity wave (MGW) propagation in the equatorial ionosphere taking into account the finite conductivity is analyzed. The dispersion relation shows the existence of two propagating MGW modes in ionospheric layer F2: high-frequency (HF MGW) and low frequency (LF MGW). The dispersion relations for them are executed and the characteristic frequencies and propagation velocities are determined. In this part of research the spectral features of disturbances in components of environment displacement for HF MGW, generated by a mass source, is carried out. The results are applied to estimate the values of density, pressure and magnetic field spectral components of magnetogravity disturbances caused by horizontal meteor sweep. They may be useful in the analysis of ionospheric disturbances excited by high energy geophysical sources.