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.

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).

Events of induced proton precipitations from the inner radiation belt have been detected. They accompanied almost a half (11) of 25 anomalous electron precipitations recorded onboard the Meteor-M No. 2 satellite in 2014−2022 in Oceania at low latitudes in the morning hours of local time under quiet geomagnetic conditions. It is surmised that such events could be provoked by proton fall into cyclotron resonance with low-frequency radiation stimulated by a mobile ionospheric heater. The observed effects in anomalous electron precipitations which may be interpreted in the framework of the mobile ionospheric heater conception are also discussed.

According to observations of the radiation situation in space from the Meteor-M No. 2 satellite, which is in a sun-synchronous circular orbit with a height of ~832 km, 25 anomalous increases in electron fluxes with a duration of ~6–8 min each were detected. These rare events were recorded in 2014–2022 in Oceania at low latitudes in the morning hours of local time under quiet geomagnetic conditions, at energies from ~100 keV to several MeV. Electron fluxes in the channel of the Cherenkov counter were observed at the level of fluxes of galactic cosmic rays in the polar caps, and in the channels of other counters, at the level of fluxes at the maximum of the outer radiation belt. It is assumed that precipitation of electrons from the inner radiation belt was observed: during bounce oscillations, electrons fell into cyclotron resonance with radio emission initiated by ground and/or ship transmitters in the morning hours of local time.

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.

— The first results of monitoring the radiation state of the near-Earth space on the Arktika-M no. 1 spacecraft in a high-apogee Molniya orbit are considered. The characteristics of the devices of the heliogeophysical instrumentation complex GGAK-HE are presented. The results of the comparative analysis of experimental and model distributions of energetic particle fluxes of the Earth’s radiation belts in the orbit of the Arktika-M no. 1 , as well as of some features of the dynamics of the outer electron radiation belt in 2021 and 2022 and the solar proton event of October 28, 2021, based on the experimental data from Arktika-M no. 1 , Meteor-M no. 2 , and Elektro-L no. 2 spacecraft are presented.

Homogeneous series of solar cosmic-ray events for four solar-activity cycles against the background of decreased activity in cycles 23 and 24 are considered. The number of solar cosmic-ray events with energies above 10 MeV decreased insignificantly, while the number of ground-level enhancements in comparison between cycles 23 and 24 decreased by eight times. It is shown that the average contribution of flares to the generation of ground-level enhancements decreased from cycle 23 to cycle 24 by three times, and the average contribution of coronal mass ejections decreased by five times; the average contribution of flares to the generation of solar cosmic rays with energy >10 MeV decreased by 1.3 times, and the average contribution of coronal mass ejections increased by 1.4 times.

Type-II radio emission often accompanies events in solar cosmic rays and is an indicator of the propagation of a shock wave in the solar corona. Conversely, the shock wave associated with coronal mass ejections plays an important role in the acceleration of solar protons. Both of these phenomena can occur unaccompanied by solar cosmic rays, while not all solar cosmic ray events are accompanied by type-II radio emission. The statistical relationships between these phenomena are considered based on the catalogs of solar proton events for the 23rd and 24th solar-activity cycles. It is shown that the events of solar cosmic rays accompanied by type-II radio emissions are among the most powerful in terms of both particle characteristics and source characteristics.

The results of a comparative analysis from Russian satellite data on the radiation environment in the near-Earth space during September–November 2020 are presented. The source of variations in the fluxes and spectra of electrons in the Earth’s outer radiation belt during this period was the high-speed fluxes of the solar wind from the coronal hole. Differences in the response of the Earth’s outer radiation belt to recurrent geomagnetic disturbances at each solar revolution are discussed.

Solar proton events are compared using the Catalogue of Solar Proton Events of the 24th Cycle of Solar Activity and solar events with long-duration high-energy gamma radiation based on measurements at the Fermi gamma-ray telescope. High-energy γ-quanta are mainly the product of the decay of π о -mesons during the interaction of high-energy protons on the Sun. Sources of gamma-ray flares not accompanied by solar protons are located in the eastern hemisphere of the Sun, and the associated coronal ejections do not move toward the Earth. Solar protons from such sources are not recorded by the terrestrial observer.

— The results of a comparative analysis of the fluxes and spectra of solar protons measured in September 2017 by satellites at different orbits (ELECTRO-L No. 2, GOES 13, and METEOR-3 No. 2) and the results of modeling of the ionization rate in the polar atmosphere based on data from these experiments are presented. It is found based on data from Russian and US satellites that the proton spectra are sufficiently close to each other and are exponential. Calculations of the ionization rate in the polar atmosphere based on data from the three experiments showed close results, except for those at low altitudes.

Results of the comparative analysis of the dynamics of SCR fluxes with energies of 1–100 MeV in the interplanetary environment according to the data of the ACE and Wind spacecraft and within the Earth’s magnetosphere according to the data of the GOES-15 and Electro-L satellites in the region of geostationary orbits, and POES-19 and Meteor-M1 in the region of polar caps during two increases in SCR of January 19–31, 2012, are presented. It is shown that the decrease in the efficiency of SCR penetration into the Earth’s magnetosphere in the region of the orbits under study on January 28, 2012, is related to the passage of the Earth’s magnetosphere through the interplanetary environment structure with a quasi-radial interplanetary magnetic field and a small pressure of the solar wind.

The authors consider methodical and practical questions of detecting penetrating radiation in "Meteor" satellites as one of the important factors affecting the equipment operation in space.To implement dosimetry estimates the authors calculated active threshold energies and geometric factors for Geiger, Cherenkov and scintillation detectors of penetrating radiation which are included in the complex KGI-4S satellite "Meteor-3M» № 1 designed to detect particles with energies up to 600 MeV for protons and up to 7 MeV for electrons .Publications with keywords:outer space ,