Galactic Cosmic Ray Intensity Research Articles

Catalogues of Forbush Decreases for the Period of 1957 - 1967

This work presents catalogues of Forbush Deceraeses (FDs) between the periods of 1957 – 1967. Forbush Decrease is a short-time decrease in the intensity of galactic cosmic rays. Such decreases are traced to solar wind disturbances. This work aims to study the catalogues of FDs. To achieve this aim, two approaches will be adopted namely; (1) downloading and presenting the IZMIRAN FDs from their website (2) applying the automated methods of FD identification developed by Okike and Umahi (2019) to identify and present FDs. The IZMIRAN catalog which applied the global survey method, identified a total of 450 FDs while the automated generated FDs (FD1 and FD2) which applied Fourier transformation, identified 500 and 458 FDs respectively. A close study on the three catalogues, pinpointed some differences and similarities. These were attributed to the differences in their methods of identification.

Cosmic Radiation Reliability Analysis for Aircraft Power Electronics

Cosmic Ray induced failures are a major concern for the electronic system reliability of airborne and space systems. Power system voltages on aerospace platforms are on a steady upward trend. High voltage power converters suffer from Single Event Burnout failures caused by cosmic rays. The established standards propose a scaling factor based on measured background galactic cosmic rays intensity at operating altitude to apply de-rating factors. The radiation environment in the atmosphere can be increased due to the cascading of primary solar energetic particles during solar eruptions. In this work, the altitude profile of the radiation environment is simulated using a GEANT4 Monte-Carlo code. The failure rates due to both background Galactic Cosmic Rays and Solar Energetic Particles are quantitatively evaluated. Further to the known influence of geomagnetic shielding of cosmic rays, the geographical distribution of cosmic rays at flight altitudes of 10 km are also presented. The estimated cosmic ray intensity can then be combined with experimentally measured failure rate data to predict the impact on the reliability of power converters, giving a new level of accuracy in the modeling of such failure mode in more electric aircraft applications. It is shown for the first time in the scientific literature by using experimental data and state-of-the-art models, that the solar energetic particles storms fluxes vastly exceed the recommended standard and constitute a risk for the power electronics reliability.

Galactic cosmic rays at 0.7 A.U. with Venus Express housekeeping data

We apply a previously developed procedure to characterize galactic cosmic rays (GCRs) at 0.7 A.U. with engineering data coming from the Venus Express mission. The engineering parameters are the Error Detection and Correction EDAC cumulative counters, used for detection and correction of memory errors induced by highly energetic particles. It has already been demonstrated that the slope of this counter measures GCR fluxes using data from Mars Express (1.5 A.U.) and Rosetta (up to 4 A.U.) data. Here, we reproduce these methods using Venus Express EDAC data in order to understand the behavior of GCRs closer to the Sun. We again witness the anti-correlation of EDAC slope with the solar activity and further investigate this procedure. The resulting time-lag between maximum sunspot number and minimum GCRs intensity at Venus is close to one day instead of the expected several months. This work represents one of the first characterization of galactic cosmic rays at small distances to the Sun over a long period of time and further cements the value of using EDAC counters as scientific information.

Fluctuations in the Intensity of Galactic Cosmic Rays during Perturbations of the Solar Wind in Early November 2021

Fluctuations in the Intensity of Galactic Cosmic Rays during Perturbations of the Solar Wind in Early November 2021

Reconstructing Sunspot Number by Forward-Modelling Open Solar Flux

The open solar flux (OSF) is the integrated unsigned magnetic flux leaving the top of the solar atmosphere to form the heliospheric magnetic field. As the OSF modulates the intensity of galactic cosmic rays at Earth, the production rate of cosmogenic isotopes – such as 14C and 10Be stored in tree rings and ice sheets – is closely related to the OSF. Thus on the basis of cosmogenic isotope data, OSF can be reconstructed over millennia. As sunspots are related to the production of OSF, this provides the possibility of reconstructing sunspot number (SSN) and hence properties of the solar cycles prior to the first sunspot telescopic observations in 1610. However, while models exist for estimating OSF on the basis of SSN, the hysteresis present in OSF and the lack of a priori knowledge of the start/end dates of individual solar cycles means that directly inverting these models is not possible. We here describe a new method that uses a forward model of OSF to estimate SSN and solar cycle start/end dates through a Monte Carlo approach. The method is tested by application to geomagnetic reconstructions of OSF over the period 1845-present, and compared to the known SSN record for this period. There is a substantial improvement in reconstruction of both the SSN time series and the solar cycle start/end dates compared with existing OSF-SSN regression methods. This suggests that more accurate solar-cycle information can be extracted from cosmogenic isotope records by forward modelling, and also provides a means to assess the level of agreement between independent SSN and OSF reconstructions. We find the geomagnetic OSF and observed SSN agree very well after 1875, but do differ during the early part of the geomagnetic record, though still agree within the larger observational uncertainties.

Fifty years of studying the GCR intensity during inversion of heliospheric magnetic fields I. Observations

The effects of the 22-year variation of solar magnetic fields in the galactic cosmic ray (GCR) intensity were first observed and interpreted as manifestations of inversion of the high-latitude solar magnetic field in properties of heliospheric magnetic fields by the Lebedev Physical Institute team in 1973. Since then, these effects have been studied already for 50 years.
 The situation with the heliospheric magnetic field is clear for periods of medium and low sunspot activity — the heliosphere consists of two unipolar “hemispheres” separated by a wavy global heliospheric current sheet and characterized by a general polarity A (unit quantity with the sign of the radial component of the heliospheric magnetic field in the northern hemisphere). Yet there is no consensus on what the inversion of the heliospheric magnetic field is and which effects in the GCR intensity are connected with this phenomenon.
 In this article, we briefly formulate general concepts of the 22-year variation in characteristics of the Sun, heliosphere, and GCR intensity and discuss the observed effects in the GCR intensity, which we attribute to the heliospheric magnetic field reversal. Models for this phenomenon and the results of GCR intensity calculations with these models will be discussed in the next article.

Пятьдесят лет исследования поведения интенсивности ГКЛ в периоды инверсии гелиосферного магнитного поля. I. Наблюдаемые эффекты

The effects of the 22-year variation of solar magnetic fields in the galactic cosmic ray (GCR) intensity were first observed and interpreted as manifestations of inversion of the high-latitude solar magnetic field in properties of heliospheric magnetic fields by the Lebedev Physical Institute team in 1973. Since then, these effects have been studied already for 50 years.
 The situation with the heliospheric magnetic field is clear for periods of medium and low sunspot activity — the heliosphere consists of two unipolar “hemispheres” separated by a wavy global heliospheric current sheet and characterized by a general polarity A (unit quantity with the sign of the radial component of the heliospheric magnetic field in the northern hemisphere). Yet there is no consensus on what the inversion of the heliospheric magnetic field is and which effects in the GCR intensity are connected with this phenomenon.
 In this article, we briefly formulate general concepts of the 22-year variation in characteristics of the Sun, heliosphere, and GCR intensity and discuss the observed effects in the GCR intensity, which we attribute to the heliospheric magnetic field reversal. Models for this phenomenon and the results of GCR intensity calculations with these models will be discussed in the next article.

Forecast of Intense Geomagnetic Storms in February-March 2023, Based on Measurements of Galactic Cosmic Ray Intensity Fluctuations

Forecast of Intense Geomagnetic Storms in February-March 2023, Based on Measurements of Galactic Cosmic Ray Intensity Fluctuations

Temporal variability of galactic cosmic ray intensity and its dependence on various solar parameters observed during solar cycles 23 and 24

Temporal variability of galactic cosmic ray intensity and its dependence on various solar parameters observed during solar cycles 23 and 24

The Influence of Corotating Regions of Interaction of the Solar Wind on Long-Term Variations in the Intensity of Galactic Cosmic Rays

An analysis of the data of spacecraft that scanned large areas of the heliosphere, as well as the resultsof magnetohydrodynamic calculations, indicates that the corotating interaction regions of solar wind (SW),which are almost always present in the low- and mid-latitude heliosphere, sometimes strongly change thelarge-scale characteristics of the heliosphere that are important for long-term variations in the intensity ofgalactic cosmic rays (GCRs). In particular, for Carrington rotation no. 2066 (January–February 2008), theseregions enhance magnetic fields in the inner (r 3–5 AU) heliosphere and weaken them in the middle andfar heliosphere, as well as significantly changing the polarity distribution of heliospheric magnetic fields. Theassumption is made that in this situation the influence of the corotating interaction regions should lead to anincrease in the GCR intensity in many regions of the heliosphere. This paper discusses the process of changingthe polarity distribution of heliospheric magnetic fields due to the interaction of SW streams for Carringtonrotation no. 2066 of different speeds, the simple model of the heliospheric magnetic field without aninteraction between the SW streams of different speeds, as well as the results of numerical two-dimensionalfinite-difference calculations of longitude-averaged GCR intensity with the use of this model in comparisonwith a three-dimensional Monte Carlo calculation based on three-dimensional magnetohydrodynamic simulationof the heliosphere.

The Influence of Corotating Regions of Interaction of the Solar Wind on Long-Term Variations in the Intensity of Galactic Cosmic Rays

The Influence of Corotating Regions of Interaction of the Solar Wind on Long-Term Variations in the Intensity of Galactic Cosmic Rays

Флуктуации интенсивности галактических космических лучей перед геомагнитной бурей 25-26 августа 2018 года

В данной работе с целью создания методов прогноза негативных проявлений космической погоды исследуется динамика флуктуаций интенсивности галактических космических лучей во время сильной геомагнитной бури 25-26 августа 2018 года. Флуктуации интенсивности космических лучей - это квазипериодические вариации с периодами менее 3-х часов, которые эпизодически возникают в межпланетном пространстве во время крупномасштабных возмущений солнечного ветра. Эти возмущения обусловлены распространением межпланетных ударных волн, выбросов корональной массы, высокоскоростных потоков, которые во многом и определяют космическую погоду. Для анализа привлекались 1-минутные исправленные на давление данные измерений нейтронных мониторов станций космических лучей Бухта Тикси и Якутск, а также 1-минутные данные прямых измерений межпланетного магнитного поля, плотности и скорости солнечного ветра на космическом аппарате WIND. В результате установлено, что перед началом бури на инерционном участке спектров турбулентности солнечного ветра в области частот ~10-4 ÷ 8.33·10-3 Гц наблюдались быстрые магнитозвуковые волны значительной амплитуды. Предполагается, что эти волны были сгенерированы в области взаимодействия медленного и быстрого потоков солнечного ветра, вызвавшего эту геомагнитную бурю. При этом поток галактических космических лучей был подвержен модуляции со стороны быстрых магнитозвуковых волн. Это проявилось в измерениях нейтронных мониторов как регистрация значимых когерентных флуктуаций интенсивности галактических космических лучей более чем за сутки до начала геомагнитной бури. Полученные результаты указывают на возможность осуществления кратковременного прогноза начала сильных геомагнитных бурь в режиме реального времени на основе использования данных измерений станций космических лучей. This paper investigates the dynamics of galactic cosmic ray intensity fluctuations during a strong geomagnetic storm on 25-26 August 2018 in order to establish methods for predicting negative space weather manifestations. Cosmic ray intensity fluctuations are quasi-periodic variations with periods of less than 3 hours, which occur episodically in interplanetary space during large-scale disturbances of the solar wind. These disturbances are due to the propagation in space of interplanetary shock waves, coronal mass ejections and high-speed solar wind flows, which largely determine space weather. The analysis involved 1-minute pressure-corrected measurement data from neutron monitors at the Tiksi Bay and Yakutsk cosmic ray stations, as well as 1-minute data from direct measurements of the interplanetary magnetic field, solar wind density and speed onboard the WIND spacecraft. As a result, it was found that immediately before the start of the storm, fast magnetosonic waves of significant amplitude were observed in the inertial section of the solar wind turbulence spectra in the frequency range ~10-4 ÷ 8.33·10-3 Hz. It is assumed that these waves were generated in the region of interaction between slow and fast solar wind streams, which caused this geomagnetic storm. At the same time, the galactic cosmic ray flux was subject to modulation by fast magnetosonic waves. This manifested in measurements of neutron monitors as the registration of significant coherent galactic cosmic ray intensity fluctuations more than a day before the onset of a geomagnetic storm. The obtained results indicate the possibility of real-time short-term prediction of the onset of strong geomagnetic storms using data measured by cosmic ray stations.

Unidirectional gradient of galactic cosmic ray intensity at different cut-off rigidities and solar magnetic polarities

Energetic charged particles known as Galactic cosmic rays (GCRs) are mostly protons originating from supernova remnants. The solar wind modulates the GCR intensity near-Earth along the solar cycles (SCs) in association with the heliospheric magnetic field (HMF). GCR intensity as observed by the neutron monitor at low, medium, high cut-off rigidities (Pc ) is employed to calculate the South-North (SN) asymmetry of GCR densities (n) of different magnetic polarity states (A) of the HMF. The study covered SCs 22/23, 23/24 and 24/25, during negative and positive states (A < 0 and A > 0). We used the modified correction for secular changes in n to determine the SN asymmetry of n (δnS−N /n) with respect to the heliospheric current sheet (HCS), a wavy structure dividing the northern and southern HMFs. We found anti-correlation of corrected tilt angle of HCS [α] for Earth’s excursions in helio-latitude with the corrected δnS−N/n, particularly during A < 0 epoch (2004-2008) and A > 0 epoch (2015-2019 not 1996-1998). The results indicate that HCS drift is crucial for asymmetric modulation and latitude gradient of GCR in both epochs. The asymmetric latitudinal gradient [G ⊥] shows strong positive correlation to the consistency between the corrected δnS−N/n and for all epochs and Pc .

Measurements of anomalous cosmic rays from the WIND spacecraft over 1994–2021

ABSTRACT Observations provide direct evidence for a sustained decline in solar activity since the 1980s, with the minimum between solar cycles 24 and 25 (P24/25) reaching its deepest trough in the past hundred years. In response to the reduced solar modulation, low-energy (&amp;lt;GeV) galactic cosmic rays (GCRs) at 1 au attain historical new highs in P24/25, while anomalous cosmic rays (ACRs) show very inconsistent variations with GCRs. To better understand the long-term ACR variations, we revisit the 6.0–13.4 MeV nuc−1 oxygen measurements from the WIND/LEMT instrument over 1994–2021, with particular interests to the recent three solar minima: P22/23 (solar magnetic polarity A &amp;gt; 0), P23/24 (A &amp;lt; 0), and P24/25 (A &amp;gt; 0). We find that the peak ACR intensities in P24/25 are ∼20 per cent lower than those in P22/23 but ∼48 per cent above those in P23/24. Additionally, for a specified heliospheric current sheet (HCS) tilt angle, the GCR intensities in P24/25 are inferred to be significantly higher than those in P22/23 (both are in A &amp;gt; 0 cycles), whereas the ACR intensities in P24/25 are close to those in P22/23. These results indicate that large variability in ACRs exists not only between opposite-polarity cycles, but also between different cycles of the same polarity, and ACRs may be more sensitive to varying HCS compared to GCRs. We speculate that variations in the ACR source intensity may be a key to understanding the ACR–GCR discrepancies. This is the first time for such a long-term study being possible with the same instrument.

New insights from cross-correlation studies between solar activity indices and cosmic-ray flux during Forbush decrease events

Observed galactic cosmic ray intensity can be subjected to a transient decrease. These so-called Forbush decreases are driven by coronal mass ejection induced shockwaves in the heliosphere. By combining in situ measurements by space borne instruments with ground-based cosmic ray observations, we investigate the relationship between solar energetic particle flux, various solar activity indices, and intensity measurements of cosmic rays during such an event. We present cross-correlation study done using proton flux data from the SOHO/ERNE instrument, as well as data collected during some of the strongest Forbush decreases over the last two completed solar cycles by the network of neutron monitor detectors and different solar observatories. We have demonstrated connection between the shape of solar energetic particles fluence spectra and selected coronal mass ejection and Forbush decrease parameters, indicating that power exponents used to model these fluence spectra could be valuable new parameters in similar analysis of mentioned phenomena. They appear to be better predictor variables of Forbush decrease magnitude in interplanetary magnetic field than coronal mass ejection velocities.

Relation of pandemics with solar cycles through ozone, cloud seeds, and vitamin D

The global records of infectious diseases, including Western and Eastern documents from 1825 to 2020, during which sunspot observations are considered reliable, show that 27 of the 34 pandemic outbreaks were coincident with sunspot number maxima or minima. There is evidence that the intensity of galactic cosmic rays is anti-correlated with solar activity and that cloud seed formation is accelerated by galactic cosmic rays. There are a substantial number of research papers showing the relationship between COVID-19 and vitamin D deficiency. The data analysis of ozone thickness measured based on NASA satellite observations revealed that ozone thickness has 11-year and 28-month cycles. Because the 11-year cycles of ozone thickness and cloud seed attenuation are anti-correlated, when either one becomes extremely thick, such as at the maximum or minimum point of solar activity, UV radiation is over-attenuated, and human vitamin D deficiency is globally increased. This finding explains the coincidence of pandemic outbreaks with the extrema of the sunspot numbers. Vitamin D supplementation can be an effective countermeasure against the spread of infectious diseases, which is a paramount importance to global society. Future pandemic forecasting should include the 11-year and 28-month cycles of UV radiation. This founding completes the relationship between solar activity and human health through the earth’s environment.

Improved Cosmic Ray Spectrum and Intensity in Middle Atmosphere (CORSIMA) Model Considering Six Characteristic Energy Intervals

&#x0D; &#x0D; &#x0D; The new model CORSIMA (COsmic Ray Spectrum and Intensity in Mid- dle Atmosphere) is presented in this study. Numerical determinations of the spectrum and intensity of Galactic Cosmic Rays (GCR) for the middle atmo- sphere and the lower altitudes of the ionosphere (30–80 km) are presented. These altitudes are above the Regener–Pfotzer maximum. The primary spec- tra of protons and helium (alpha particles) are used. According to the amount of particles, cosmic rays consist of 92% protons, 6% helium nuclei, 1% heavier elements, and 1% electrons (GINZBURG and SIROVATSKY [19]).&#x0D; We also use the approximation of ionization losses (Bohr–Bethe–Bloch formula) in six characteristic energy intervals, including the charge decrease interval for electron capture. In this way, the accuracy of the obtained results is improved.&#x0D; Analytical expressions for the contributions of the energy intervals are provided. An approximation of the ionization function on six energy intervals is used and the charge decrease interval for electron capture is studied. Numerical calculations are performed using computational algebra systems.&#x0D; The development of this research is important for a better understanding of the processes and mechanisms of space weather. The GCR affect the ionization and electrical parameters in the atmosphere and also the chemical processes (ozone formation and depletion in the stratosphere) in it. These effects can be significantly enhanced during strong and moderately strong solar proton events and geomagnetic storms.&#x0D; &#x0D; &#x0D;

Modulation of Galactic Cosmic Ray Intensity in the Approximation of Small Anisotropy

Modulation of Galactic Cosmic Ray Intensity in the Approximation of Small Anisotropy

The modulation of galactic cosmic ray intensity in the small anisotropy approximation

The modulation of galactic cosmic ray intensity in the small anisotropy approximation

On the Energy Dependence of Galactic Cosmic Ray Anisotropies in the Very Local Interstellar Medium

We report on the energy dependence of Galactic cosmic rays (GCRs) in the very local interstellar medium (VLISM) as measured by the Low Energy Charged Particle (LECP) instrument on the Voyager 1 spacecraft. The LECP instrument includes a dual-ended solid-state detector particle telescope mechanically scanning through 360° across eight equally spaced angular sectors. As reported previously, LECP measurements showed a dramatic increase in GCR intensities for all sectors of the ≥211 MeV count rate (CH31) at the Voyager 1 heliopause (HP) crossing in 2012; however, since then the count rate data have demonstrated systematic episodes of intensity decrease for particles around 90° pitch angle. To shed light on the energy dependence of these GCR anisotropies over a wide range of energies, we use Voyager 1 LECP count rate and pulse height analyzer (PHA) data from ≥211 MeV channel together with lower-energy LECP channels. Our analysis shows that, while GCR anisotropies are present over a wide range of energies, there is a decreasing trend in the amplitude of second-order anisotropy with increasing energy during anisotropy episodes. A stronger pitch angle scattering at higher velocities is argued as a potential cause for this energy dependence. A possible cause for this velocity dependence arising from weak rigidity dependence of the scattering mean free path and resulting velocity-dominated scattering rate is discussed. This interpretation is consistent with a recently reported lack of corresponding GCR electron anisotropies.