The article presents the results of a comparative analysis of the solar proton event on March 30, 2022, which has an unusual time profile of solar proton fluxes, and the previous and subsequent solar proton events (March 28, 2022, and April 02, 2022). Increases in energetic proton fluxes in the interplanetary and near-Earth space are associated with successive solar X-ray flares M4.0, X1.3, and M3.9 and three halo-type coronal mass ejections. The study was based on experimental data obtained from spacecraft located in the interplanetary space (ACE, WIND, STEREO A, and DSCOVR), in a circular polar orbit at an altitude of 850 km (Meteor-M2) and in geostationary orbit (GOES-16, Electro-L2). An explanation has been proposed for the specific features of the energetic proton flux profile in the solar proton event on March 30, 2022: protons accelerated in the flare on March 30, 2022 were partially screened by an interplanetary coronal mass ejection, the source of which was the explosive processes on the Sun on March 28, 2022; late detection of maximum proton fluxes, simultaneous for particles of different energies, is due to the arrival of particle fluxes inside an interplanetary coronal mass ejection. The spatial distribution of solar protons in near-Earth orbit was similar to the distribution at the Lagrange point L1 but with a delay of 50 min.

The parameters of dimmings and their relation to coronal mass ejections (CMEs) are studied to determine the location of possible sources of ejections on the solar disk during solar cycle 24. We used the Solar Demon database, which contains information on flares and dimmings obtained by processing images from the SDO/AIA space observatory. Of all the analyzed dimmings, 16

The paper demonstrates results of modeling arrival time of coronal mass ejections (CME) to near-Earth space with parameters of coronal dimmings in 2010–2018. We use drag-based model (DBM) for CME propagation and empirical model for quasi-stationary solar wind streams. We compared the ICME arrival time and speed forecast for events with coronal source in the central region of the solar disk based on the CME initial speed using (1) CACTus database; (2) dimming maximum intensity drop from Solar Demon database to calculate the initial speed of the CME. Results show that the methods result in similar errors. To study the possibility of predicting ICME, for which a CME may not be observed in the coronagraph for some reason, modeling of ICME was carried out using dimming parameters. In 43

We discuss the reasons for the extreme compression of the magnetosphere during the storm on February 27, 2023, when the magnetopause crossed the geostationary orbit. At the same time, aurora was observed at middle latitudes. The global parameters of magnetospheric current systems were calculated from data on the parameters of the interplanetary medium and geomagnetic indices characterizing the evolution of the ring current and the westward auroral electrojet, using a paraboloid model of the magnetosphere. We have calculated the contributions of various current systems to the observed value of the D_st index. The contribution of the tail current sheet is comparable with the contribution of the ring current for this storm. The calculated modelled field is compared with the data of the GOES-16, 18 magnetometers; the results are in good agreement with observations.

Представлены результаты исследования потоков солнечных протонов с энергией больше 5 МэВ в околоземном космическом пространстве 13–23.III.2023. Особенностями исследуемого периода являются отсутствие наблюдаемой солнечной вспышки, с которой можно ассоциировать начало события, нехарактерный временной профиль потоков протонов, а также большая длительность существования потоков солнечных протонов в околоземном пространстве. Предпринята попытка объяснить источники наблюдаемых вариаций потоков частиц и понять, что происходило на Солнце и в окружающем Землю пространстве. Источником солнечных протонов 13.III.2023 был взрывной процесс на обратной от Земли стороне Солнца, зарегистрированный как корональный выброс массы очень большой мощности. Причиной длительного и сложного временного профиля солнечных протонов был вклад процессов ускорения частиц на Солнце и в межпланетной среде, а также модуляция потоков частиц структурами межпланетного магнитного поля. Предложен возможный сценарий, объясняющий существование повышенных потоков солнечных частиц 15–23.III.2023: формирование гелиосферной структуры – замкнутой области-­ловушки, образованной двумя межпланетными корональными выбросами массы и областями взаимодействия высокоскоростных и медленных потоков солнечного ветра. В работе использованы экспериментальные данные, полученные с космического аппарата Solar Orbiter и с космических аппаратов, расположенных вблизи точки L1 системы Земля – Солнце (ACE и DSCOVR) и на геостационарной орбите (GOES-16).

The results of studying the fluxes of solar protons with energies greater than 5 MeV in near-Earth space on March 13–23, 2023, are presented. The features of the period under study are no visible solar flare with which the beginning of the event could be associated and an untypical time profile of proton fluxes, as well as a long duration of the existence of solar proton fluxes in near-Earth space. An attempt was made to explain the sources of the observed different variations in particle fluxes and to understand what happened on the Sun and in the near-Earth space. The source of solar protons on March 13, 2023, was an explosive process on the back side of the Sun from the Earth, registered as a coronal mass ejection of very high power. The reason for the long and complex time profile of solar protons was the contribution of particle acceleration processes on the Sun and in the interplanetary medium, as well as the modulation of particle fluxes by the structures of the interplanetary magnetic field. A possible scenario has been proposed to explain the existence of increased fluxes of solar particles on March 15–23, 2023: the formation of a heliospheric structure, this being a closed trap region formed by two interplanetary coronal mass ejections and regions of interaction of high-speed and slow solar wind streams. The study uses experimental data obtained from the Solar Orbiter spacecraft and from spacecraft located near the L1 point of the Earth–Sun system (ACE and DSCOVR) and in geostationary orbit (GOES-16).

The paper presents the results of studying the dynamics of the magnetic field and electron fluxes of the Earth’s outer radiation belt with an energy of >2 MeV according to the GOES-15 geostationary satellite during a fairly long period (October 16, 2016 to February 16, 2017) of moderate and weak magnetospheric activity caused by the arrival of a sequence of high-speed solar wind streams. The main variations in the electron flux in the geostationary orbit are caused by the movement, deceleration and acceleration of particles in the outer radiation belt of the Earth under the influence of geomagnetic activity. The results of a comparative analysis of variations in electron fluxes and components of the magnetospheric field testify to the predominant influence of the magnitude and structure of the magnetospheric field on the dynamics of relativistic electron fluxes in the outer radiation belt. Changes in the components of the magnetospheric magnetic field and in electron fluxes are results of a single process that occurs together with changes in the magnetosphere as a whole.

The TUS detector was a highly sensitive orbiting telescope. Due to the spacecraft’s polar orbit, the detector was able to observe the UV emission of the atmosphere above the polar auroral oval. Events with vintensity variations characteristic of pulsating auroras were detected along the equatorial boundary of the auroral oval. These variations occurred during prolonged geomagnetic disturbances. When compared to data from charged particle detectors, they revealed an increased flux of precipitating high-energy electrons with energies of more than 100 keV along with UV pulsations.

Последние годы интенсивно развивается наука, изучающая Вселенную. Вселенная включает в себя пространство, время, материю и энергию.

The authors demonstrate the possibility of using CubeSat nanosatellites to study solar cosmic rays (SCRs). SCR electron fluxes over the polar caps at altitudes of ∼550 km are detected. Measurements are made using scintillation detectors of cosmic radiation (DeCoR) mounted on several CubeSat nanosatellites of Moscow State University during an SCR event on September 6–21, 2022.

Electron fluxes with energies >0.3 MeV have been measured on the SiriusSat-1 satellite in the final stage of its flight in the altitude range from 400 to 180 km in the region of the South Atlantic anomaly. The existing models of distributions of electron fluxes in the near-Earth space such as the АЕ8 and АЕ9 models primarily concern trapped particles in radiation belts at altitudes above 400 km. Data on subrelativistic electron fluxes at altitudes below 300 km are almost absent. Since the SiriusSat-1 satellite operated until its burning in the atmosphere, unique measurements of the altitude behavior of subrelativistic electron fluxes have been performed, in particular in the region of the South Atlantic anomaly.

A study is performed of solar proton events that occurred during periods of the reversal of the Sun’s magnetic field in cycles 19–24 of solar activity. Periods 8–12 months long and falling on the times of the magnetic field’s reversal are found in each solar cycle. The number of solar events and the total and maximum proton fluences are reduced during these periods, while the energy spectra are softer than those in preceding and subsequent periods of the same duration. In most of the considered cycles, the above periods begin after their maxima or during local Gnevyshev minima.

There have been a number of theories proposed concerning the loss of relativistic electrons from the radiation belts. However, direct observations of loss were not possible on a number of previous missions due to the large field of view of the instruments and often high-altitude orbits of satellites that did not allow researchers to isolate the precipitating electrons from the stably trapped. We use measurements from the ELFIN-L suit of instruments flown on Lomonosov spacecraft at LEO orbit, which allows us to distinguish stably trapped from the drift loss cone electrons. The sun-synchronous orbit of Lomonosov allows us to quantify scattering that occurred into the loss cone on the dawn-side and the dusk-side magnetosphere. The loss at MeV energies is observed predominantly on the dawn-side, consistent with the loss induced by the chorus waves. The companion data publication provides processed measurements.

Within the framework of the Moscow University space project SOZVEZDIE-270, a constellation of cubesat nano-satellites with a set of instruments is being deployed, which, among other goals, provides monitoring of the near-Earth space radiation environment, control of the geo- and heliophysical conditions. Along with the space constellation, a network of ground receiving stations is also being created. During the project implementation, 11 spacecraft of the cubesat format have been launched to date. Currently, there are 6 such spacecraft operating in near-Earth orbit, which transmit scientific and telemetric data. During 2023–2024 it is planned to launch at least 8 more such satellites into low circular polar orbits. Multi-satellite constellation has been implemented, which makes it possible to carry out simultaneous measurements of particle and quantum fluxes using the same type of instruments at different points in the near-Earth space. Such measurements provide unique information about the sub-relativistic electron flux dynamics, including variations due to precipitation, which is of great importance for understanding the mechanisms of trapped and quasi-trapped electron acceleration and losses.

The results of a study of energetic electron precipitation from the Earth’s outer radiation belt into the atmosphere during weak geomagnetic storm on February 1–5, 2015 are presented. The work was carried out on the basis of experimental data on electron fluxes with energies >0.1, >0.3, and >2 MeV obtained from Meteor-M2 polar satellite. For a comparative analysis of the electron fluxes of the outer radiation belt, precipitating and trapped, Van Allen Probes data were used. It is shown that the strongest precipitation are observed during the main phase of the storm and in the beginning of the recovery phase, when prolonged intense substorm activity occurs. In spite of significant precipitation in the wide L-MLT area as was found in [6], decrease in the flux of trapped electrons at the belt maximum during the main phase of the storm was not observed. Moreover, during the late recovery phase, the flux of electrons with E > 2 MeV increased, while that with E > 0.1 and E > 0.3 MeV did not change.

The new approaches to the modelling of the Sun-solar wind-magnetosphere-radiation belts chain and their implementation at MSU's Space weather center (Space Monitoring Data Center, SMDC) are presented. The main idea is to use data from medium-term (3-5 days) forecasts of the speed of quasi-stationary solar wind streams based on data obtained from solar images in the UV wavelength range to improve the quality of forecasts of the magnetospheric factors of the space environment. An operational model for predicting the daily fluence of relativistic electrons (>2 MeV) in the Earth's outer radiation belt has been developed, with the extended set of input parameters that include the forecast of the solar wind velocity. To validate the model, the period from October 11, 2016 to February 18, 2017 was considered, during which the Sun made several revolutions and it was possible to observe the evolution of coronal holes and the devel-opment of solar sporadic phenomena. The arrival of high-speed solar wind streams from coronal holes to the Earth's magnetosphere, as well as, as impact of coronal mass ejections, provoked geomagnetic disturbances of various intensity, and caused significant variations of the electron fluxes of the Earth's outer radiation belt. SMDC website implements solar wind model based on the data of solar observa-tions by the AIA instrument of the SDO space observatory at wavelengths of 19.3 and 21.1 nm that forecasts the daily fluence of rel-ativistic electrons (E > 2 MeV) in geostationary orbit. It is shown that the use of the results of medium-term forecasting of the solar wind speed as an input parameter in the daily electron fluence forecast model can significantly improve its quality with a forecast horizon of up to 4 days.(c) 2022 COSPAR. Published by Elsevier B.V. All rights reserved.

Distinguishing features of a series of solar proton event (SPE) catalogs for the 20th–24th cycles of solar activity are described. The results of a comparative analysis of the 23rd and 24th cycles of solar activity performed according to the data of a series of SPE catalogs are presented. The opportunities provided by SPE catalogs for studying space weather factors, such as the dynamics of solar activity, the structure and state of the interplanetary medium, and the Earth’s magnetosphere are discussed.