First measurements of low-energy cosmic rays on the surface of the lunar farside from Chang’E-4 mission

The intensity of low-energy cosmic rays on the lunar farside is consistent with that observed in the near-earth space.

Comparative case study of two methods to assess the eruptive potential of selected active regions

Solar eruptive events, like flares and coronal mass ejections, are characterized by the rapid release of energy that can give rise to emission of radiation across the entire electromagnetic spectrum and to an abrupt significant increase in the kinetic energy of particles. These energetic phenomena can have important effects on the space weather conditions and therefore it is necessary to understand their origin, in particular, what is the eruptive potential of an active region (AR). In these case studies, we compare two distinct methods that were used in previous works to investigate the variations of some characteristic physical parameters during the pre-flare states of flaring ARs. These methods consider: i) the magnetic flux evolution and magnetic helicity accumulation, and ii) the fractal and multi-fractal properties of flux concentrations in ARs. Our comparative analysisis based on time series of photospheric data obtained bythe Solar Dynamics Observatory between March 2011 and June 2013. We selected two distinct samples of ARs: one is distinguished by the occurrence of more energetic M- and X-class flare events, that may have a rapid effect on not just the near-Earth space, but also on the terrestrial environment; the second is characterized by no-flares or having just a few C- and B-class flares. We foundthat the two tested methods complement each other in their ability to assess the eruptive potentials of ARs and could be employed to identify ARs prone to flaring activity. Based on the presented case study, we suggest that using a combination of different methods may aid to identify more reliably the eruptive potentials of ARs and help to better understand the pre-flare states.

On the group velocity of whistling atmospherics

The dynamic spectrum of a whistling atmospheric is a signal of falling tone, and the group delay time of the signal as a function of frequency is formed as a result of propagation of a broadband pulse in a medium (magnetospheric plasma) with a quadratic dispersion law. In this paper, we show that for quadratic dispersion the group velocity is invariant under Galilean transformations. This means that, contrary to expectations, the group velocity is paradoxically independent of the velocity of the medium relative to the observer. A general invariance condition is found in the form of a differential equation. To explain the paradox, we introduce the concept of the dynamic spectrum of Green’s function of the path of propagation of electromagnetic waves from a pulse source (lightning discharge in the case of a whistling atmospheric) in a dispersive medium. We emphasize the importance of taking into account the motion of plasma in the experimental and theoretical study of electromagnetic wave phenomena in near-Earth space.

Cluster analysis of lightning discharges: based on Vereya-MR network data

Monitoring thunderstorm activity can help you solve many problems such as infrastructure facility protection, warning of hazardous phenomena associated with intense precipitation, study of conditions for the occurrence of thunderstorms and the degree of their influence on human activity, as well as the influence of thunderstorm activity on the formation of near-Earth space. We investigate the characteristics of thunderstorm cells by the method of cluster analysis. We take the Vereya-MR network data accumulated over a period from 2012 to 2018 as a basis. The Vereya-MR network considered in this paper is included in networks operating in the VLF-LF range (long and super-long radio waves). Reception points equipped with recording equipment, primary information processing systems, communication systems, precision time and positioning devices based on global satellite navigation systems are located throughout Russia. In the longitudinal-latitudinal thunderstorm distributions of interest, the dependence on the location of recording devices might be manifested. We compare the behavior of thunderstorms on the entire territory of the Russian Federation with those in the Baikal natural territory. We have established the power of thunderstorms over the Baikal region is lower. The daily variation in thunderstorm cells we obtained is consistent with the data from other works. There are no differences in other thunderstorm characteristics between the regions under study. This might be due to peculiarities of the analysis method. On the basis of the work performed, we propose sites for new points of our own lightning location network, as well as additional methods of cluster analysis.

On the group velocity of whistling atmospherics

The dynamic spectrum of a whistling atmospheric is a signal of falling tone, and the group delay time of the signal as a function of frequency is formed as a result of propagation of a broadband pulse in a medium (magnetospheric plasma) with a quadratic dispersion law. In this paper, we show that for quadratic dispersion the group velocity is invariant under Galilean transformations. This means that, contrary to expectations, the group velocity is paradoxically independent of the velocity of the medium relative to the observer. A general invariance condition is found in the form of a differential equation. To explain the paradox, we introduce the concept of the dynamic spectrum of Green’s function of the path of propagation of electromagnetic waves from a pulse source (lightning discharge in the case of a whistling atmospheric) in a dispersive medium. We emphasize the importance of taking into account the motion of plasma in the experimental and theoretical study of electromagnetic wave phenomena in near-Earth space.

Cluster analysis of lightning discharges: based on Vereya-MR network data

Monitoring thunderstorm activity can help you solve many problems such as infrastructure facility protection, warning of hazardous phenomena associated with intense precipitation, study of conditions for the occurrence of thunderstorms and the degree of their influence on human activity, as well as the influence of thunderstorm activity on the formation of near-Earth space. We investigate the characteristics of thunderstorm cells by the method of cluster analysis. We take the Vereya-MR network data accumulated over a period from 2012 to 2018 as a basis. The Vereya-MR network considered in this paper is included in networks operating in the VLF-LF range (long and super-long radio waves). Reception points equipped with recording equipment, primary information processing systems, communication systems, precision time and positioning devices based on global satellite navigation systems are located throughout Russia. In the longitudinal-latitudinal thunderstorm distributions of interest, the dependence on the location of recording devices might be manifested. We compare the behavior of thunderstorms on the entire territory of the Russian Federation with those in the Baikal natural territory. We have established the power of thunderstorms over the Baikal region is lower. The daily variation in thunderstorm cells we obtained is consistent with the data from other works. There are no differences in other thunderstorm characteristics between the regions under study. This might be due to peculiarities of the analysis method. On the basis of the work performed, we propose sites for new points of our own lightning location network, as well as additional methods of cluster analysis.

MONITORING THE ARTIFICIAL SPACE OBJECTS WITH UKRAINIAN NETWORK OF OPTICAL STATIONS

The article describes the successes and challenges of the Ukrainian network of optical stations (UMOS) in recent years in the field of astrometric observations of artificial space objects both in low-Earth orbit (LEO) and geostationary Earth orbit (GEO). UMOS was established in 2012 as a joint partnership of organizations interested in satellite observations for scientific purposes and practical near Earth space monitoring. The main purpose of the UMOS has been (and still is) to combine scientific and technical means with regular optical (positional and / or non-positional) observation. The short list of equipment of the UMOS members are given in the tables. The programs for observations, used methods and obtained results are described in the paper. In conclusion, the advantages of observations of artificial space objects by means of a network are summarized. The experience of UMOS and main results obtained by UMOS can be considered as the first step to create the SSA system of Ukraine.

Method of Wavelet-Decomposition to Research Cosmic Ray Variations: Application in Space Weather

Since their discovery, cosmic rays have been an integral part of the development of fundamental physics, from the discovery of radiation coming to the Earth from outer space and the identification of high-energy particles in it, as well as new fundamental symmetries in the laws of nature, to the knowledge of residual matter and magnetic fields in interstellar space. Cosmic rays are used in a number of fundamental and applied research in solar-terrestrial physics and are important in the research of the near-Earth space processes. Cosmic ray variations observed on the Earth’s surface are an integral result of various solar, heliospheric, magnetospheric and atmospheric phenomena. The most significant changes in cosmic ray parameters are caused by coronal mass ejections and subsequent changes in the parameters of the interplanetary magnetic field and solar wind. Therefore, the study of cosmic rays makes it possible to obtain valuable information about the processes in the near-Earth space and in the Earth’s magnetosphere during disturbed periods. This article proposes a method for analyzing cosmic ray variations. It is based on the use of wavelet data decomposition operations and their combination with threshold functions. By using adaptive thresholds, the operations for detecting anomalous changes in data and for suppressing the noise were developed. Anomalies in cosmic rays can cause radiation hazard for astronauts, radio communication failures, as well as malfunctions in satellites, leading to the loss of orientation and destruction. Therefore, the task of timely diagnostics of anomalies is urgent. The paper describes the algorithms for the implementation of the method and shows their application in the space weather problem. We used data from the network of ground stations of neutron monitors. The efficiency of the method for detecting abnormal changes of different amplitudes and durations is shown. Application of the method made it possible to detect clearly and to evaluate Forbush effects in cosmic rays, which precede the onset of magnetic storms of various nature and strength.

Activities Of The Yakutsk Geophysical Observatory (Cosmic Ray Laboratory) In 1928–1962

The relevance of the research topic is related to the generalization of the Soviet experience in formation and development of cosmophysical research in Yakutia over several decades, from the activities of weather stations to the creation of the Institute of Cosmophysical Research and Aeronomy of the Yakutsk Branch of the USSR Academy of Sciences. The formation of the network of 23 stationary meteorological and upper-air stations and the Geophysical Observatory is disclosed. The first stage of the activity of these institutions was identified as of high practical importance in the development of aviation, gold mining industry on Aldan and Amur-Yakutsk highway construction.The second stage was characteristic by innovative developments of Yakut scientists as semiconductor devices for artificial Earth satellites, cameras for shooting auroras, and an ionization camera for continuous registration of cosmic rays, that received worldwide recognition. Study of radiation situation in near-Earth space during solar flares and high-altitude thermonuclear explosions testified, that Yakutia contributed to increasing of the country's defense capability. Particular attention is paid to the activities of the station on Bolshoy Lyakhovsky Island of the Novosibirsk Islands, which served Arctic aviation flights and coastal navigation along the Northern Sea Route.

Can Satellite Mega-constellations Justify Their Impact on Astronomy?

Near-earth space is being increasingly commercialised by private space companies. This has many consequences for science, particularly, astronomy. Some estimates show that more than 100,000 satellites may orbit the Earth by 2030. Satellite mega-constellations for satellite Internet connectivity are one of the main drivers behind the explosion in the number of satellites. Here, we briefly note whether such satellite mega-constellations can justify their impact on astronomy.