Cosmic Ray Variations Research Articles

Method of global survey involving data of muon telescope network

In 1967, the Yu.G. Shafer Institute of Cosmophysical Research and Aeronomy developed a global survey method that allowed application of the global network of neutron monitors as a single device, simultaneously oriented to various directions and providing information on distribution of cosmic rays per each measured moment. By analogy with this approach, a method for calculation of anisotropy parameters of high-energy cosmic rays has been proposed, involving measurement data from the Global Muon Detector Network and Yakutsk stations. To implement the method, receiving vectors of the stations have been calculated, making it possible to consider associations between cosmic ray variations in the interplanetary medium and those observed at Earth. The paper also discusses some methodological issues related to correct determination of angular distribution of cosmic rays in the interplanetary space. Based on the modified method of global survey, parameters of the first two moments of the angular distribution of cosmic rays for 2012–2018 have been calculated.

Galactic Cosmic Rays, Cosmic-Ray Variations, and Cosmogenic Nuclides in Meteorites

Abstract We present a new generation of model calculations for cosmogenic production rates in various types of solar system bodies. The model is based on the spectra for primary and secondary particles calculated using the INCL++6 code, which is the most reliable and most sophisticated code available for spallation reactions. Thanks to the recent improvements (extending the code to lower and higher energies and considering light charged particles as ejectiles and projectiles), we can for the first time directly consider primary and secondary Galactic α particles. We calculate production rates for 22Na, 10Be, and 26Al in an L-chondrite with a radius of 45 cm and in the Apollo 15 drill core, and we determine the long-term average Galactic cosmic-ray (GCR) spectrum (represented by the solar modulation potential Φ) in the meteoroid orbits at ∼3 au of Φ = 600 MV and at 1 au, i.e., for Earth and Moon of Φ = 660 MV. From this, we calculate a long-term average GCR gradient in the inner solar system of ∼5% au−1. Finally, we discuss the possibility of studying temporal GCR variations and meteoroid orbits using production rate ratios of short- and long-lived radionuclides.

Solar activity and Earth seismicity

Using the results of continuous long-term observations over 50 years (including solar cycles 20–24), we study the relationship between Earth’s seismicity and solar activity. An increase in the number of strong earthquakes on the planet occurs during the decline phase of solar activity when charged particle fluxes from high-latitude coronal holes increase, as well as during solar minimum when the intensity of galactic cosmic rays reaches a maximum. The change in the number of strong earthquakes (with magnitude 6) is considered in terms of variations in the intensity of galactic cosmic rays, Forbush decreases, and ground level enhancements in solar cosmic rays (GLE events). The number of strong earthquakes is shown to increase after Forbush decreases with a time lag from ~1 to ~6 days depending on the amplitude of Forbush decrease and after GLE events the number of strong earthquakes increases by ~8 day. In the number of strong earthquakes, a six-month variation is observed, which seems to follow the six-month variation in cosmic rays with a delay of ~1–2 months. It is surmised that the relationship between solar activity and Earth’s seismicity seems to be mediated through the modulation of galactic cosmic rays and atmospheric processes that provoke the occurrence of earthquakes in regions where the situation has already been prepared by tectonic activity.

Солнечная активность и сейсмичность Земли

Using the results of continuous long-term observations over 50 years (including solar cycles 20–24), we study the relationship between Earth’s seismicity and solar activity. An increase in the number of strong earthquakes on the planet occurs during the decline phase of solar activity when charged particle fluxes from high-latitude coronal holes increase, as well as during solar minimum when the intensity of galactic cosmic rays reaches a maximum. The change in the number of strong earthquakes (with magnitude 6) is considered in terms of variations in the intensity of galactic cosmic rays, Forbush decreases, and ground level enhancements in solar cosmic rays (GLE events). The number of strong earthquakes is shown to increase after Forbush decreases with a time lag from ~1 to ~6 days depending on the amplitude of Forbush decrease and after GLE events the number of strong earthquakes increases by ~8 day. In the number of strong earthquakes, a six-month variation is observed, which seems to follow the six-month variation in cosmic rays with a delay of ~1–2 months. It is surmised that the relationship between solar activity and Earth’s seismicity seems to be mediated through the modulation of galactic cosmic rays and atmospheric processes that provoke the occurrence of earthquakes in regions where the situation has already been prepared by tectonic activity.

The Intensity and Evolution of the Extreme Solar and Geomagnetic Storms in 1938 January

Abstract Major solar eruptions occasionally direct interplanetary coronal mass ejections (ICMEs) to Earth and cause significant geomagnetic storms and low-latitude aurorae. While individual extreme storms are significant threats to modern civilization, storms occasionally appear in sequence, acting synergistically, and cause “perfect storms” on Earth. The stormy interval in 1938 January was one of such cases. Here, we analyze the contemporary records to reveal its time series on their source active regions, solar eruptions, ICMEs, geomagnetic storms, low-latitude aurorae, and cosmic-ray (CR) variations. Geomagnetic records show that three storms occurred successively on January 17/18 (Dcx ≈ −171 nT), January 21/22 (Dcx ≈ −328 nT), and January 25/26 (Dcx ≈ −336 nT). The amplitudes of the CR variations and storm sudden commencements (SSCs) show the impact of the first ICME as the largest (≈6% decrease in CR and 72 nT in SSC) and the ICMEs associated with the storms that followed as more moderate (≈3% decrease in CR and 63 nT in SSC; ≈2% decrease in CR and 63 nT in SSC). Interestingly, a significant solar proton event occurred on January 16/17 and the Cheltenham ionization chamber showed a possible ground-level enhancement. During the first storm, aurorae were less visible at midlatitudes, whereas, during the second and third storms, the equatorward boundaries of the auroral oval were extended down to 40.3° and 40.0° in invariant latitude. This contrast shows that the initial ICME was probably faster, with a higher total magnitude but a smaller southward component.

Recurrence of galactic cosmic-ray intensity and anisotropy in solar minima 23/24 and 24/25 observed by ACE/CRIS, STEREO, SOHO/EPHIN and neutron monitors

Aims.We studied the 27-day variations of galactic cosmic rays (GCRs) based on neutron monitor (NM), ACE/CRIS, STEREO, and SOHO/EPHIN measurements in the solar minima 23/24 and 24/25, which are characterized by the opposite polarities of solar magnetic cycle. We used the opportunity to reanalyze the polarity dependence of the amplitudes of the recurrent GCR variations in 2007–2009 for the negativeA < 0 solar magnetic polarity and to compared it with the clear periodic variations related to solar rotation in 2017–2019 for positiveA > 0.Methods.We used the Fourier analysis method to study the periodicity in the GCR fluxes. Because the GCR recurrence is a consequence of solar rotation, we analyzed not only GCR fluxes, but also solar and heliospheric parameters to examine the relations of the 27-day GCR variations and heliospheric as well as solar wind parameters.Results.We find that the polarity dependence of the amplitudes of the 27-day variations of the GCR intensity and anisotropy for NMs data is kept for the last two solar minima: 23/24 (2007–2009) and 24/25 (2017–2019), with greater amplitudes in the positiveA > 0 solar magnetic polarity. ACE/CRIS, SOHO/EPHIN, and STEREO measurements are not governed by this principle of greater amplitudes in the positiveA > 0 polarity. The GCR recurrence caused by the solar rotation for low-energy (< 1 GeV) cosmic rays is more sensitive to the enhanced diffusion effects, resulting in the same level in 27-day amplitudes for the positive and negative polarities. In contrast, the high-energy (> 1 GeV) cosmic rays that are registered by NMs are more sensitive to the large-scale drift effect, which leads to the 22-year Hale cycle in the 27-day GCR variation, with the larger amplitudes in theA > 0 polarity than inA < 0.

On the Rigidity Spectrum of Cosmic-Ray Variations within Propagating Interplanetary Disturbances: Neutron Monitor and SOHO/EPHIN Observations at ∼1–10 GV

Abstract The rigidity dependence of all Forbush decreases (FDs) recorded from 1995 to 2015 has been determined using neutron monitor (NM) and Solar and Heliospheric Observatory (SOHO) (EPHIN) spacecraft data, covering the energy (rigidity) range from ∼433 MeV (1 GV) to 9.10 GeV (10 GV). We analyzed a total of 421 events and determined the spectrum in rigidity with an inverse power-law fit. As a result, the mean spectral index was identified to be 〈γ F 〉 = 0.46 ± 0.02. The majority (∼66%) of the FDs have γ F within the range 0.3–0.7. The remaining one-third of the events (∼33%) have either (very) soft or hard FD spectra, with the latter being more common than the former. Significant variations of γ F occur within almost every FD event. During the initial FD decay phase the spectrum becomes gradually harder, in contrast to the recovery phase, when it becomes softer. Additionally, low energies (rigidities) seem to be better suited for studying the fine structure of interplanetary disturbances (primarily interplanetary coronal mass ejections) that lead to FDs. In particular, FDs recorded by the EPHIN instrument on SOHO better capture a two-step structure than FDs observed by NMs. Finally, the ejecta of an ICME, especially when identified as a magnetic cloud, often leads to abrupt changes in the slope of γ F .

The Possible Relationship between the Atmospheric Electric Field and High Energy Charged Particles and the COVID-19 Cases in the Central Arabian Peninsula

Background: Since the beginning of the global COVID-19 pandemic, several studies have been carried out to investigate its spread, with a wide range of factors to understand the influence of the factors that contribute to its spread and to reduce the ongoing threat of COVID-19 pandemic. Methods: In this study, the relationships between the Earth’s electric field and cosmic ray charged particles of different energy ranges and the daily confirmed COVID-19 infections in Riyadh, Saudi Arabia have been investigated using non-parametric statistical tests. The data covered the period between 3 April 2020 and 1st August 2021 and were obtained from the King Abdulaziz City for Science and Technology (KACST) CARPET detector, Riyadh, Saudi Arabia. The electric fields data were obtained from electric field monitor (EFM) deployed on the rooftop of the KACST laboratory. The data of the daily COVID-19 cases were obtained from the official webpage of the Saudi Arabian Ministry of Health (MOH). Results: The results revealed that that the number of COVID-19 cases is correlated with cosmic ray charged particles and anti-correlated with the Earth’s electric field. Conclusion: While the exact mechanism explaining the influence of Earth’s electric field and cosmic rays variations on the reported number of COVID-19 cases is not yet established, the results presented in this study can add additional knowledge to our understanding of the effects of additional factors on influenza activities.

Solar wind temperature–velocity relationship over the last five solar cycles and Forbush decreases associated with different types of interplanetary disturbance

ABSTRACT The behaviour of the solar wind (SW) proton temperature and velocity and their relationship during Forbush decreases (FDs) associated with various types of solar source – coronal mass ejections (CMEs) and coronal holes (CHs) – have been studied. Analysis of cosmic ray variations, SW temperature, velocity, density, plasma beta, and magnetic field (from 1965–2019) is carried out using three databases: the OMNI database, Variations of Cosmic Rays database (IZMIRAN) and Forbush Effects & Interplanetary Disturbances database (IZMIRAN). Comparison of the observed SW temperature (T) and velocity (V) for the undisturbed SW allows us to derive a formula for the expected SW temperature (Texp, the temperature given by a T–V formula, if V is the observed SW speed). The results reveal a power-law T–V dependence with a steeper slope for low speeds (V < 425 km s−1, exponent = 3.29 ± 0.02) and flatter slope for high speeds (V > 425 km s−1, exponent = 2.25 ± 0.02). A study of changes in the T–V dependence over the last five solar cycles finds that this dependence varies with solar activity. The calculated temperature index KT = T/Texp can be used as an indicator of interplanetary and solar sources of FDs. It usually has abnormally large values in interaction regions of different-speed SW streams and abnormally low values inside magnetic clouds (MCs). The results obtained help us to identify the different kinds of interplanetary disturbance: interplanetary CMEs, sheaths, MCs, corotating interaction regions, high-speed streams from CHs, and mixed events.

Statistical associations of teleconnection indices and space weather with spring weather pattern in the Eastern Baltic region

AbstractThe studies of associations between solar inputs and climate are mostly designed for winter or cold period; whereas the knowledge about these associations during spring on a day‐to‐day time scale are very scarce. Therefore, the aim of this study is to detect the response of spring air temperature (T), relative humidity (RH), and atmospheric pressure (ATP) to variation in teleconnection indices and space weather variables on the day‐to‐day timescale during the period of 1998–2017 in six cities of Eastern part of the Baltic region. We created a multivariate linear regression model for weather variables including month, the linear and seasonal trend, different teleconnection patterns, El Niño–Southern Oscillation, the Quasi‐biennial Oscillation phase, the presence of Sudden Stratospheric Warming (SSW) and space weather variables. The multivariate models for the mean daily weather variables showed a positive association between T and the daily Arctic oscillation, monthly Scandinavian pattern (SCA) indices, solar proton events (SPEs) with a lag of 1–9 days, and solar wind dynamic pressure (P) with a lag of 1–2 days and negative association between T and East Atlantic/West Russia (EA/WR) index. The mean RH positively correlated with a long‐term and short‐term variation in galactic cosmic rays (GCR) and solar wind speed (SWS) with a lag of 0–6 days and negatively correlated with EAWR and NINO3.4 indices. The mean ATP was negatively associated with both long‐term and short‐term changes in GCR and positively associated with the North Atlantic oscillation, EA/WR and SCA indices, By component of interplanetary magnetic field with a lag of 2 days, P, days of Stream Interaction Regions (SIRs) and SWS with a lag of 4–6 days. These results show the significant short‐term effects of SSW, SPEs, SIRs and solar wind variables on spring weather pattern in the Eastern part of the Baltic region.

Ground-based Instrument for the Study of Cosmic Ray Variation in Nur-Sultan

Cosmic rays are the main factor in atmospheric ionization; they affect the formation of clouds and determine the properties of the global electrical circuit. The mechanisms of atmospheric processes involving cosmic rays are very complex and are far from understanding. Their research requires experimental installations distributed around the world. In this context a cosmophysical complex consisting of the CARPET installation, a neutron detector, and an EFM-100 electric field monitor was created in 2015 at Eurasian National University in collaboration with the Lebedev Physical Institute of the Russian Academy of Sciences. This paper presents a brief summary of the characteristics of the CARPET facility and experimental data obtained in the period 2016–2019. Some results of the analysis of the characteristics of cosmic-ray flux variations recorded by this complex and the accompanying conditions in the Earth’s magnetosphere and in the interplanetary medium are presented.

Long‐Term Variations of Quasi‐Trapped and Trapped Electrons in the Inner Radiation Belt Observed by DEMETER and SAMPEX

AbstractElectrons in the Earth's radiation belts can be categorized into three populations: precipitating, quasi‐trapped, and trapped. We use data from the Detection of Electro‐Magnetic Emissions Transmitted from Earthquake Regions (DEMETER) and Solar, Anomalous, and Magnetospheric Particle Explorer satellite (SAMPEX) missions and from ground‐based neutron monitors (NM) and sunspot observations to investigate the long‐term variation of quasi‐trapped and trapped sub‐MeV electrons on different L shells in the inner belt. DEMETER and SAMPEX measurements span over 17 years and show that at L ≤ 1.14 the electron flux is anticorrelated with sunspot number, but proportional to the cosmic ray intensity represented by NM count rates, which suggests that electrons at the inner edge of the inner belt are produced by Cosmic Ray Albedo Neutron Decay (CRAND). The solar cycle variation of cosmic rays increased the electron flux at L ≤ 1.14 by a factor of 2 from solar maximum at 2001 to solar minimum at 2009. At L ≥ 1.2, both quasi‐trapped and trapped electrons are enhanced during geomagnetic storms and decay to a background level during extended quiet times. At L > 2, quasi‐trapped electrons resemble trapped electrons, with correlation coefficients as high as 0.97, indicating that pitch angle scattering is the dominant process in this region.

New Insights From Long-Term Measurements of Inner Belt Protons (10s of MeV) by SAMPEX, POES, Van Allen Probes, and Simulation Results.

The Solar, Anomalous, and Magnetospheric Particle Explorer (SAMPEX) mission provided long‐term measurements of 10s of megaelectron volt (MeV) inner belt (L < 2) protons (1992–2009) as did the Polar‐orbiting Operational Environmental Satellite‐18 (POES‐18, 2005 to present). These long‐term measurements at low‐Earth orbit (LEO) showed clear solar cycle variations which anticorrelate with sunspot number. However, the magnitude of the variation is much greater than the solar cycle variation of galactic cosmic rays (>GeV) that are regarded as a source of these trapped protons. Furthermore, the proton fluxes and their variations sensitively depend on the altitude above the South Atlantic Anomaly (SAA) region. With respect to protons (>36 MeV) mirroring near the magnetic equator, both POES measurements and simulations show no obvious solar cycle variations at L > 1.2. This is also confirmed by recent measurements from the Van Allen Probes (2012–2019), but there are clear solar cycle variations and a strong spatial gradient of the proton flux below L = 1.2. A direct comparison between measurements and simulations leads to the conclusion that energy loss of trapped protons due to collisions with free and bound electrons in the ionosphere and atmosphere is the dominant mechanism for the strong spatial gradient and solar cycle variation of the inner belt protons. This fact is also key of importance for spacecraft and instrument design and operation in near‐Earth space.

Time variations in Galactic cosmic rays as measured from Southeast Asia

We summarizetime variations in Galactic cosmic ray (GCR) measurements from the Princess Sirindhorn Neutron Monitor(PSNM) at the summit of Doi Inthanon, Thailand’s highest mountain, since 2007. PSNM is the first neutron monitor (NM) station making long-term measurements in Southeast Asia, with the world’s highest cutoff (threshold) rigidity (momentum per charge) of ≈17 GV. GCR variations with the ∼11-year sunspot cycle or ∼22-year solar magnetic cycle are known as solar modulation. Compared with measurements at lower cutoff, PSNM reveals a distinct pattern of solar modulation related to the interplanetary magnetic field strength. NM viewing directions rotate with Earth, so daily (“diurnal”) variations indicate the GCR anisotropy, and we identified time intervals with unusually strong anisotropy due to a unidirectional GCR gradient. From worldwide NM data, we determine an hourly anisotropy during GCR decreases associated with solar storms, indicating GCR flows consistent with our previous theory that cosmic rays drift into one leg of an interplanetary flux rope and out the other. PSNM was also the first fixed NM to monitor time delays between successive neutrons, providing a proxy for the cosmic ray spectral index using data from a single station, avoiding the systematic uncertainties of cross-station comparisons.

Ring of Stations Method in Cosmic Rays Variations Research

For over 60 years, neutron monitors have been the main standard and high precision detectors for measuring cosmic rays with energy from 400 MeV to hundreds GeV. In order to obtain sufficiently complete information about the distribution of cosmic rays outside the magnetosphere, it is necessary to have a network of detectors spaced evenly enough around the globe. The ring of stations method is one of the most useful methods for studying the properties of the angular distribution of cosmic rays without expressing the cosmic ray intensity in terms of spherical harmonics. The method allows one to get the hourly longitude distribution of the cosmic ray intensity without modeling. The main objective of this work is to expand the use of the ring of stations method, as it is a convenient and useful method of studying cosmic ray variation. Using the ring of stations method, it is possible to study specific angular distributions of cosmic ray variation that are described poorly by the sum of the first spherical harmonics. The ring of stations method is primarily used to study Forbush decreases. Detailed descriptions of Forbush decrease investigation by the ring of stations method are presented in this study. The application of the method to the study of the precursors of Forbush decreases and cosmic rays behavior inside the solar wind disturbances is shown.

Impact of Ground-Level Enhancement (GLE) Solar Events on Soft Error Rate for Avionics

This article proposes to study the impact of ground-level enhancement (GLE) induced by extreme solar flares on the soft error rate (SER) for flight representatives to the world-air traffic. A GLE physical model was confronted to cosmic ray variations measured with neutron monitors during the GLEs 5 and 69. Based on said GLE physical model and single-event upset occurrence models, investigations were performed to assess the SER during these GLEs for a bulk 90-nm commercial off-the-shelf SRAM. The main conclusion is that the GLE impact must be considered in the risk assessment, which requires a physical description of the additional solar cosmic rays and a realistic consideration of the air traffic.

Station-Ring Method in the Study of Cosmic-Ray Variations: 2. Examples of Its Use

The station-ring method makes it possible to isolate and study the specific angular distributions of cosmic-ray variations that are poorly described by the sum of the first spherical harmonics. Examples of the use of the station-ring method are given and described in detail. The application of the method to study precursors of Forbush effects and the behavior of cosmic rays inside the perturbations of the solar wind is shown.

Association of solar flux (2800 MHz) and cosmic ray intensity for solar cycle 22 and 23

The variation of galactic cosmic rays in the heliosphere in correlation with the solar activity presents a high scientific interest for several aspects. The possibility of studying the energy charge (& mass), spatial & temporal distribution of cosmic rays in the interstellar space, in the vicinity of the solar system, can provide a better understanding of astrophysical mechanism like, for instance, the acceleration of charged particles in a shocked plasma. Galactic cosmic rays in turn can be used as a unique tool for deeply understanding the characteristics & the dynamics of the heliosphere. So it is necessary & significant to investigate the role of various solar parameters in the variation of galactic cosmic rays. Solar radio flux is the energy emitted by the sun with a slowly varying intensity. The amount of this energy is high in the corona & it changes gradually day to day in response to the numbers of spot groups on the solar disk.

Variations of cosmic rays in the period 2016-2019 according to observations of the ENU experimental complex

Variations of cosmic rays in the period 2016-2019 according to observations of the ENU experimental complex

Полугодовая вариация космических лучей и ионосферы

Полугодовая вариация космических лучей и ионосферы