High-latitude observations from the Polar Geophysical Institute are used to study the development of a typical auroral substorm that occurred on September 13, 2013. According to satellite data, the event was linked to parameters of the solar wind and physical domains and boundaries of the magnetosphere. Characteristics of the spatial structure of polar auroras (scaling indices, anisotropy) are determined for typical auroral structures (quiet and rayed arcs, breakup, pulsating bands, and omega structures).

The geophysical processes in the dayside polar cusp on December 22, 2003 under the northern orientation of the interplanetary magnetic field (IMF), relatively high speed and low density of the solar wind by using the ground-based optical observations on Spitsbergen and DMSP F16 spacecraft observations were examined. A comparison of spacecraft and ground-based observations shows that soft electron precipitation in the cusp region determine the region of the auroral luminosity in the (OI) 630.0 nm emission. The peculiarity of the event under consideration is the observation of a bright rayed auroral arc bordering the dayside cusp from its polar edge. The results of observations of the low-altitude DMSP F16 spacecraft during its pass over the rayed arc were analyzed. Explanations of the observed phenomena are proposed based on the analysis of changes in the spectra of precipitating electrons and the formation of an electron beam by a field-aligned electric field.

Geophysical processes in the region of the dayside polar cusp on December 22, 2003, were studied for a northern orientation of the interplanetary magnetic field (IMF) and a relatively high-velocity, low-density solar wind, using ground-based optical observations in Svalbard and DMSP F16 satellite data. Comparison of satellite and ground-based observations shows that soft electron precipitation in the cusp region determines the auroral glow in the 630.0 nm (OI) emission. The peculiarity of the considered event is observation of a bright rayed arc of the aurora rimming the dayside cusp from its polar edge. The results of observations by the low-flying DMSP F16 satellite as it intersected the rayed arc were analyzed. Explanations for the observed phenomena are proposed, based on analysis of changes in the spectra of precipitating electrons and formation of a field-aligned electron beam by the field-aligned electric field.

In this work, we discuss the problems associated with the formation of the outer radiation belt (ORB) taking into account previous results, including the recent ones. In our opinion, the traditional approaches to the dynamics of the ORB have the following problems: • inconsistency between the times provided by the popular “quasilinear” approach to the ORB description and the observed electron acceleration times; • impossibility to describe ORB dynamics during magnetospheric storms using the “quasilinear” approach when the particle fluxes after storm restore to their pre-storm values, i.e., belong to the storms of the third type according to Reeves et al. (2003, https://doi.org/10.1029/2002GL016513 ) classification; • impossibility of explaining the Tverskaya’s relation, which connects the position of the maximum of the relativistic flux formed after storm with the minimum value of the Dst/SYM-H variation, as well as the acceleration of relativistic electrons during magnetospheric substorms even in the absence of storms. We show that such difficulties do not appear if we take into account the large- scale magnetospheric dynamics, including auroral oval shift toward low latitudes during storms, substorm injections into the region of depressed magnetic field during storm recovery phase and the action of the adiabatic mechanism of electron deceleration and acceleration. The action of stochastic mechanisms of ORB acceleration is also discussed.

The results of observations of low-altitude spacecraft crossing the daytime sector of the auroral zone and of high-apogee spacecraft in the equatorial plane of the magnetosphere were analyzed in order to identify the main processes leading to the formation of dayside polar cusps. Observations from the DMSP F7 spacecraft were used to analyze the latitudinal characteristics of ion precipitation in the cusp region and to study the latitudinal profile of ion pressure in the cusp depending on the IMF parameters. A significant difference was found in identifying the cusp boundaries using an automated data processing system and direct analysis of spacecraft observations. It is shown that for small negative values of the Bz-component of the IMF (〈Bz〉 = –3.0 nT), an ordinary feature of the cusp is the latitudinal profile of the ion pressure (Pi) with a width of 1° of latitude with two maxima, one of which is located in the equatorward and the other in the poleward of the cusp. For large negative Bz values (–6, –8 nT), the polar maximum in the latitudinal profile Pi disappears; only the equatorial maximum remains, the Pi level at the maximum increases, and the width of the cusp decreases to 0.7°. For Bz IMF > 0, the most characteristic is the Pi profile with a maximum ion pressure in the polar part of the cusp. The cusp for Bz > 0 is located at higher latitudes than for Bz < 0, and its average latitudinal width increase to 1.4° of latitude. In the prenoon sector MLT, the most typical for periods with a large negative By-component of the IMF (〈By〉 = –6.3 nT, 〈Bz〉 = –1.7 nT) is a cusp with a width of 1.4° of latitude with a flat top in the latitudinal Pi profile. Comparison of the pressure distributions observed at low heights with data from high-apogee satellites confirmed the possibility of describing the formation of the cusp as a diamagnetic cavity and using observations in the cusp to determine the ion pressure in the magnetosheath.

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

The most recent findings on the dynamics of the outer radiation belt (ORB) and the physics of magnetospheric substorms are examined. Specifically, we investigate the relationship between storm time substorms and the energetic electron population that forms the ORB. Traditionally, storm time substorms have been considered as the primary source of energetic electrons, which are further accelerated during storms to contribute to the formation of the ORB. However, several observations have demonstrated that large magnetospheric substorms can generate high-energy electrons even in the absence of magnetic storms. Substorms introduce dispersionless injections of energetic electrons deep into the magnetosphere from the geosynchronous orbit during storm times. The injected electrons undergo additional acceleration via the betatron mechanism during the storm recovery phase, thus increasing the ORB population. To gain a better understanding of this process, it is crucial to study plasma sheet turbulence, substorm onset processes, and the brightening of auroral arcs. By analyzing the aforementioned findings, this study aims to highlight the need for reanalyzing of the role of auroral processes in the formation of the ORB.

The unique trajectories of DMSP spacecraft relative to a dayside polar cusp are considered. They allow the cusp precipitation to be characterized in different longitudinal sectors for short time intervals of 2–3 min. The latitudinal widths of a cusp depend on the magnetic local time (MLT) and differ considerably in the pre- and after-noon sectors. A large-scale trend in ion energy fluxes upon a change in MLT can be observed in a cusp, along with smaller variations in energy fluxes having longitudinal dimensions of ~100–150 km. The latitudinal widths of a cusp are determined mainly by the solar wind dynamic pressure (Psw). The width of a cusp is 2.0°–2.5° of latitude at Psw = 17–19 nPa and only ~0.3° at Psw ≈ 1.0 nPa.

The data from the DMSP spacecraft were used to study the characteristics of ion and electron precipitation in the nightside sector of the auroral zone during magnetically quiet periods at extreme values of the solar wind dynamic pressure ( Psw ). It was shown that the ion pressure at the isotropy boundary (IB) increases with Psw and can reach a level of 4–6 nPa at Psw = 20–22 nPa. The latitude profiles of the ion pressure obtained at different levels of Psw indicate that the increase in Psw is accompanied by an expansion of the ion precipitation region and a shift of the IB to lower latitudes. At 〈 Psw 〉 = 0.5 nPa, the IB latitude is ~70.4° CGL, while at 〈 Psw 〉 = 16.3 nPa, it shifts toward the equator to ~64.6° CGL. As the Psw level decreases, the energy fluxes of precipitating electrons decrease significantly. At Psw < ~ 2.0 nPa, auroras in the region of the auroral oval can be considered subvisual. At extremely low values of dynamic pressure, Psw = ~ 0.2 nPa, it becomes very problematic to identify the zone of electron and ion precipitation.

Observations from the low-orbit DMSP satellites are used to study dynamics of the ion pressure and latitude of the isotropy boundary (IB) under significant but different changes in the solar wind dynamic pressure. High coefficients of correlation between the ion pressure at the IB and its latitude are found for two events. Possible reasons for such dynamics of IB parameters are discussed.

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.

The dependence of scattering in the F2 layer on geomagnetic activity and solar wind parameters is investigated using the example of two isolated strong magnetic storms on March 17 and June 22–23, 2015. It is shown that Moscow was in the region of the auroral oval precipitations during the magnetic storms, and the recorded F- scattering was the result of the superpositioning of several processes. The dependence of F -scattering recorded in the main phase of the June magnetic storm on indices AL and Dst is determined along with the dynamic pressure of the solar wind.

We analyzed the problems of formation of the outer radiation belt (ORB) taking into consideration the latest changes in our understanding of the high-latitude magnetospheric topology. This includes strong evidence that the auroral oval maps to the outer part of the ring current, meanwhile the ORB polar boundary maps inside the auroral oval. Our analysis also includes the variation of the plasma pressure distribution and the time of the acceleration of relativistic electrons during geomagnetic storm. It is shown that the maximum of ORB is formed after the geomagnetic storm in the region of plasma pressure maximum. The position of this maximum agrees with the prediction of the ORB formation theory based on the analysis of ring current development during storm. We emphasize the role of adiabatic processes in the ORB dynamics and the importance of the substorm injections during storm recovery phase for the formation of enhanced fluxes of ORB electrons after the storm.

Data from the DMSP F6 and F7 satellites are used to show that during the magnetic calm the ion pressure in the region of the ionospheric projection of the low-latitude boundary layer does not depend on the Bz component of the interplanetary magnetic field but grows rapidly along with the dynamic pressure of the solar wind. A local increase in ion pressure in the midday sector is detected, and its possible manifestation in the intensity of high-latitude dayside auroras is discussed.

The Earth's magnetosphere is mainly a collisionless plasma system with non-Maxwellian particle distributions, which are often fitted by the kappa function. While the Maxwell distribution function is described by two parameters (density and temperature), the kappa distribution function has three parameters: density, core energy, and the kappa index that characterizes the slope at high energies. In this study, we fitted an ion flux measured by the five Time History of Events and Macroscale Interactions during Substorms satellites in the Earth's magnetosphere during quiet geomagnetic conditions by a single kappa distribution function. The data were constrained to the following regions: from seven Earth Radii (7 RE) to the Earth's magnetopause at the dayside, and up to 20 RE for other magnetic local time sectors. The two-dimensional spatial distribution of the fitted parameters and their radial dependencies were analyzed. Regions of high and low kappa-parameter are selected and their formation is discussed.

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.

An analysis is performed of the statistical relationship between coronal mass ejections and solar flares to establish the sequence of these events. Periods of delay in the occurrence of coronal mass ejections relative to the associated flare-like manifestations of solar activity are determined. It is found that situations in which flares occur several hours ahead of coronal ejections predominate.

An analysis is performed for data from the Russian METEOR-M2 spacecraft and the RBSP/Van Allen probes received during several magnetic storms with D st < –100 nT. The high latitude trapping boundary of electrons with energies >100 keV is shown to be localized inside the region of auroral precipitations and sometimes coincides with the polar boundary of an auroral oval. The contribution from the adiabatic effect to the drops in relativistic electron fluxes during the main phase of a storm and their growth during the recovery phase is determined.

The ion pressure in the regions of ionospheric projections of the plasma mantle, polar cusp, low-latitude boundary layer, and the region of structured precipitation of the auroral oval during magnetic calm is studied based on data from the DMSP F6 and F7 low-altitude spacecraft. It is shown that the level of ion pressure in all of these regions does not depend on either the polarity or the value of the Bz component of the IMF. The ion pressure in the mantle varies from 0.02 to 0.06 nPa and does not depend on the magnitude of the solar wind dynamic pressure. The average pressure level is $$\left\langle {Pm} \right\rangle $$ = 0.03 ± 0.01 nPa. In the cusp area at IMF Bz > 0, the ion pressure (Pc) does not depend on the solar wind dynamic pressure (Psw), while the pressure at IMF Bz < 0 increases significantly with the increasing in Psw. The average pressure level is $$\left\langle {Pc} \right\rangle $$ = 1.0 ± 0.3 nPa, which is almost two orders of magnitude higher than that in the mantle. The ion pressure also increases with the solar wind dynamic pressure in both the LLBL and the auroral oval precipitation (AOP). The average pressure in the LLBL is $$\left\langle {{{P}_{L}}} \right\rangle $$ = 0.27 ± 0.07 nPa, while in the AOP region its average value is two times lower. The MLT pressure pattern in LLBL shows a pronounced increase in the noon sector (~11–14 MLT), the value of which increases with increasing in the solar wind dynamic pressure. In the AOP region the pressure is distributed over MLT fairly evenly, which results in a significant pressure difference (ΔP = PL – PA) in the noon sector between the low-latitude boundary layer and the auroral oval.