Variation Of Cosmic Ray Intensity Research Articles

The Forbush decrease observed by the SEVAN particle detector network in the 25th solar activity cycle

The temporal variations of cosmic-ray intensity, measured by ground-based detectors at various latitudes and altitudes, are related to the geophysical and solar phenomena. The latter are interplanetary coronal mass ejections and fast solar wind from coronal holes, which cause interplanetary magnetic field (IMF) abrupt variations near Earth. Interacting with the magnetosphere, they cause worldwide sudden decreases (Forbush decreases, FDs) of intensity followed by gradual recovery. The amplitude of the flux depletion depends on the type and energy of the registered particle, which in turn depends on geographical coordinates and the detector’s energy threshold and selective power. SEVAN particle detector network with nodes in Europe and Armenia selects three types of particles that demonstrate coherent depletion and recovery and correspond to different energy galactic protons interacting with disturbed magnetospheric plasmas.On November 3-4, 2021, an interplanetary coronal mass injection (ICME) hit the magnetosphere, sparking a strong G3-class geomagnetic storm and auroras as far south as California and New Mexico. All detectors of the SEVAN network have registered a Forbush decrease (FD) of ≈ 5% depletion in a 1-minute time series of count rates. Approaching the maximum solar activity cycle, large variations of the particle flux intensity were registered on February 27, March 23, 2023, and March 24, 2024.In this work, we present measurements of these FDs performed on mountain altitudes on Aragats (Armenia), Lomnicky Stit (Slovakia), Mileshovka (Czechia), and at sea level DESY (Hamburg, Germany). We compared FD measurements made by SEVAN detectors and neutron monitors located on Aragats and Lomnicky Stit and made a correlation analysis of FD registration at different locations.

Trends in childhood leukemia incidence in urban countries and their relation to environmental factors, including space weather.

Leukemia is the most common cancer in children. Its incidence has been increasing worldwide since 1910th, suggesting the presence of common sources of the disease, most likely related to people's lifestyle and environment. Understanding the relationship between childhood leukemia and environmental conditions is critical to preventing the disease. This discussion article examines established potentially-carcinogenic environmental factors, such as vehicle emissions and fires, alongside space weather-related parameters like cosmic rays and the geomagnetic field. To discern the primary contributor, we analyze trends and annual variations in leukemia incidence among 0-14-year-olds in the United States, Canada, Australia, and Russia from 1990 to 2018. Comparisons are drawn with the number of vehicles (representing gasoline emissions) and fire-affected land areas (indicative of fire-related pollutants), with novel data for Russia introduced for the first time. While childhood leukemia incidence is rising in all countries under study, the rate of increase in Russia is twice that of other nations, possibly due to a delayed surge in the country's vehicle fleet compared to others. This trend in Russia may offer insights into past leukemia levels in the USA, Canada, and Australia. Our findings highlight vehicular emissions as the most substantial environmental hazard for children among the factors examined. We also advocate for the consideration of potential modulation of carcinogenic effects arising from variations in cosmic ray intensity, as well as the protective role of the geomagnetic field. To support the idea, we provide examples of potential space weather effects at both local and global scales. The additional analysis includes statistical data from 49 countries and underscores the significance of the magnetic field dip in the South Atlantic Anomaly in contributing to a peak in childhood leukemia incidence in Peru, Ecuador and Chile. We emphasize the importance of collectively assessing all potentially carcinogenic factors for the successful future predictions of childhood leukemia risk in each country.

Investigating the heliosphere, magnetosphere, atmosphere, and properties of cosmic rays during the 2018 Aug 25–26 strong geomagnetic storm

We investigated the conditions of the heliosphere, magnetosphere, and atmosphere from cosmic ray (CR) observations during the 2018 Aug 25–26 strong geomagnetic storm. The analysis involved the global survey (GS) and the spectrographic global survey (SGS) methods created and developed at the Yu.G. Shafer Institute of Cosmophysical Research and Aeronomy of the Siberian Branch of the Russian Academy of Sciences (ShICRA SB RAS) and at the Institute of Solar-Terrestrial Physics of the Siberian Branch of the Russian Academy of Sciences (ISTP SB RAS). Also, in our analysis, we used the data on direct measurements of the interplanetary medium parameters from the known OMNI database, CR measurements at the GOES geostationary satellites, from the global network of neutron monitors and muon detectors, from the Sayan spectrograph, and from the A.I. Kuzmin Yakutsk spectrograph of CR. When analyzing this event, the SGS enabled to obtain the data on the orientation of the mean interplanetary magnetic field, on the geomagnetic cutoff rigidity and its variations during the geomagnetic storm. Also, this method allowed us to estimate the bulk temperature over the point of recording CR, the ring current and the magnetopause current, as well as their contributions to the Dst-index, and also to establish differential rigidity spectra of CR at different stages of the magnetic storm evolution. Through the GS method, we determined the value and the directions for the first two spherical harmonics of CR distribution, and the direction to their anisotropy source. The results obtained through two different global survey methods are shown to be agree and mutually supplement each other. Using the Yakutsk spectrograph records enabled to determine the index for the power energy spectrum of variations in CR intensity during the investigated event.

Variations of cosmic ray intensity with the solar flare index, coronal index, and geomagnetic indices: Wavelet and cross correlation approaches

In this study, the cosmic ray stuff and its associations with the solar flare index, coronal index, and geomagnetic indices, such as Kp, auroral electrojets, Ap, disturbance storm time (Dst), polar cap, Lyman-alpha, Hp60, and Ap60 indices, were studied using wavelet-based approaches over KIEL and MOSC stations during 2003 and 2004. The cosmic ray data used in this study were obtained from ground-based neutron monitor stations. Different sources are also used to get data on the different indices used in this study. The yearly variation in cosmic ray intensity revealed that the intensity of cosmic rays over KIEL and MOSC stations was greater in 2004 and lower in 2003. This variation might be due to the ring current's asymmetry, which causes an enormous asymmetry in the storm-time cosmic-ray increase. The wavelet coherence transform shows a positive and negative correlation as well as cosmic ray lags with solar flares and coronal indices throughout different months of the 2003 and 2004 periods over both suggested stations. The results of cross correlation indicate that cosmic ray intensity is positively correlated with all geomagnetic indices. However, cosmic ray intensity was negatively associated with the Dst index during 2003 and 2004 over both suggested stations. Moreover, multi-resolution analysis and power spectral density (PSD) analysis are consistent with wavelet analysis. Using the PSD result, we have seen high-power wavelet regions during geomagnetically quiet months and low-power wavelets during disturbed months at a common frequency over both stations during 2003 and 2004.

Study of long-term cosmic ray intensity variation with sunspot numbers, solar flare index, interplanetary magnetic fields and Alfven Mach number during solar cycle 24

Study of long-term cosmic ray intensity variation with sunspot numbers, solar flare index, interplanetary magnetic fields and Alfven Mach number during solar cycle 24

Correction of the Temperature Effect of Muon Counts Observed at the Guangzhou Station

Muons are the main component of secondary cosmic rays, and the variation in muon intensity indicates the variation in primary cosmic ray intensity. However, before using muons to study the variation in the intensity of cosmic rays, it is necessary to eliminate the atmospheric effects, such as pressure and temperature effects. In this work, the temperature effect of the muons is corrected in terms of empirical method by using ground temperature. The temperature correction is applied to the muon data observed at the Guangzhou station during the period 2010–2021 after a barometric correction. It is found that the effect of seasonal variations in temperature on muon counts is greatly eliminated in the corrected data. Furthermore, the muon data are well correlated with the neutron data in comparison, which verifies the reliability of the corrected muon data. Our results show that the correction of muon data by using ground temperature is an effective method.

Cosmic ray intensity variation in relation with solar wind plasma parameters during the period of 1997-2007

Cosmic ray intensity variation in relation with solar wind plasma parameters during the period of 1997-2007

Cosmic ray intensity variation in relation with sunspot numbers and geomagnetic activity parameter Kp and Ap index during the period of 1997-2007

Cosmic ray intensity variation in relation with sunspot numbers and geomagnetic activity parameter Kp and Ap index during the period of 1997-2007

Statistical Associations between Geomagnetic Activity, Solar Wind, Cosmic Ray Intensity, and Heart Rate Variability in Patients after Open-Heart Surgery

The aim of this study was to identify associations of the parameters of heart rate variability (HRV) with the variations in geomagnetic activity (GMA), solar wind, and cosmic ray intensity (CRI) in patients after coronary artery bypass grafting or valve surgery in Kaunas, Lithuania, during 2008–2012. The data from 5-minute electrocardiograms (ECGs) in 220 patients were used. ECGs were carried out at 1.5 months, 1 year, and 2 years after the surgery (N = 495). A lower (higher) very-low-frequency-band (VLF) and a higher (lower) high-frequency band (HF) in normalised units (n.u.) were associated with a low maximal daily 3-hourly ap (the DST index > 1). A lower mean standard deviation of beat-to-beat intervals (SDNN) and VLF, LF, and HF powers were lower in patients when Ap < 8 occurred two days after the surgery, and a low solar wind speed (SWS) occurred two days before the ECG. The effect of CRI was non-significant if the linear trend was included in the model. Low GMA and a low SWS may effect some HRV variables in patients after open-heart surgery. The GMA during the surgery may affect the SDNN in short-term ECG during the longer period.

Variations of Cosmic ray intensity in relation to Sunspot Number and Solar Wind Parameters over the period 1996-2019

Variation of Solar Wind Parameters (Proton density, Speed of SW and IMF-BZ) are changes with Cosmic ray intensity during solar cycle 23 and 24. In this work, we using the cosmic ray intensity (CRI) variation data from Oulu (Rc = 0.81GV) neutron monitors and solar-interplanetary activity data used from OMNIWeb data center for the analysis. The work includes solar wind speed, interplanetary magnetic field Bz and solar wind proton density selected indices during the period 1996-2019. Variation of solar wind plasma and interplanetary magnetic field coefficients has been studied with CRI. The study of the correlation between Sunspot number and cosmic ray intensity has been analyze and found inversely correlated with coefficient r = - 0.87. It is found that there is a linear negative correlation between Solar wind speed verses the cosmic ray intensity with correlation coefficient -0.53. The interplanetary magnetic field (IMF-Bz) shows a high negative correlation (r = -0.90) with Cosmic ray intensity for the solar cycle 23 and 24. The weak positive correlation coefficient has been found yearly average value of Cosmic ray intensity (CRI) with proton density (r = 0.19) for the study period. The solar wind index shows very remarkable relationship with CRI.

Cosmic ray intensity variation with solar flare index, solar coronal index and sunspot numbers solar indices during the period of 1986- 2007

Cosmic ray intensity variation with solar flare index, solar coronal index and sunspot numbers solar indices during the period of 1986- 2007

Variation in Cosmic-Ray Intensity Lags Sunspot Number: Implications of Late Opening of Solar Magnetic Field

Abstract Galactic cosmic rays (GCRs), the highly energetic particles that may raise critical health issues for astronauts in space, are modulated by solar activity, with their intensity lagging behind the variation in sunspot number (SSN) by about one year. Previously, this lag has been attributed to the combined effect of outward convecting solar wind and inward propagating GCRs. However, the lag’s amplitude and its solar-cycle dependence are still not fully understood. By investigating the solar surface magnetic field, we find that the source of heliospheric magnetic field—the open magnetic flux on the Sun—already lags behind SSN before it convects into the heliosphere along with the solar wind. The delay during odd cycles is longer than that during sequential even cycles. Thus, we propose that the GCR lag is primarily due to the very late opening of the solar magnetic field with respect to SSN, though solar wind convection and particle transport in the heliosphere also matter. We further investigate the origin of the open flux from different latitudes of the Sun and find that the total open flux is significantly contributed by that from low latitudes, where coronal mass ejections frequently occur and also show an odd–even cyclic pattern. Our findings challenge existing theories, and may serve as the physical basis of long-term forecasts of radiation dose estimates for manned deep-space exploration missions.

The Frequency‐Domain Characterization of Cosmic Ray Intensity Variations Before Forbush Decreases Associated With Geomagnetic Storms

AbstractNonrecurrent geomagnetic storms caused by Coronal Mass Ejection (CME) can induce serious impacts on space‐ and ground‐based equipment. However, these nonrecurrent geomagnetic storms are hard to predict since CMEs are not periodic. Previous studies have shown that the variations of Cosmic Ray Intensity (CRI) before nonrecurrent storms may forebode the coming geomagnetic storm. But it is difficult to extract the variations since the cosmic ray flux is a complex signal. In order to identify the precursory signal in CRI variations triggered by CME, an ensemble self‐adaptive time‐frequency analysis method was proposed and applied to 65 nonrecurrent geomagnetic storms occurred between 1998 and 2019. The results indicate that the precursory signals are successfully identified in 43 of 45 storms, after excluding 20 storms accompanied by ground level enhancement. In addition, it is also found that the spectral density of the precursory signal could reflect the active level of geomagnetic condition, which is lower during geomagnetic quiet period.

Human Physiological Parameters Related to Solar and Geomagnetic Disturbances: Data from Different Geographic Regions

It is well known that the various manifestations of space weather can influence a wide range of human activities, from technological systems to human health. Various earlier, as well as more recent multi-disciplinary heliobiological and biometeorological studies have revealed that the human organism is sensitive to environmental physical activity changes and reacts to them through variations of the physiological parameters of the human body. This paper constitutes an overview of the National and Kapodistrian University of Athens investigations in regard to the possible effect of solar, geomagnetic, and cosmic ray activity on human physiological parameters. The Athens Cosmic Ray and Solar Physics Groups collaborated with scientific teams from different countries, statistically processing and analyzing data related to human physiological parameters (such as mean heart rate, arterial systolic, and diastolic pressure), or the number of incidents of different types of cardiac arrhythmias and so forth, in relation to data concerning and describing geomagnetic activity (geomagnetic indices Ap and Dst) and variations in cosmic ray intensity (Forbush decreases and cosmic ray intensity enhancements). In total, four projects were carried out concerning data from different geographical regions (Baku, Azerbaijan; Kosice, Slovakia; Tbilisi, Georgia; Piraeus, Greece), covering different time periods and time scales (daily data or yearly data), and referring to different groups of individuals (selected healthy persons or random persons). The studies concluded with interesting results concerning the possible influence of geomagnetic and cosmic ray activity on the human physiological state.

Barometric coefficient dependence on the geomagnetic cutoff rigidity of neutron monitors

Several studies have been showing that cosmic ray intensity variations observed at the Earth surface can be a useful tool to analyze and predict space weather and climate phenomena. However, before reach the ground level, the cosmic ray particles interact with different atmospheric atoms. This results in the generation of different secondary particles that are differently affected by atmospheric effects. For example, data from neutron monitors, which are widely used to study cosmic ray flux changes related to space phenomena, are significantly affected by atmospheric pressure changes. Thus, for a more detailed study of these instruments’ data, it is necessary to know very well how works the pressure affects secondary neutrons. In this way, we seek to understand how this effect changes according to the cosmic rays’ energy. Thus, in this work, we compare how the barometric coefficient ( β ), which quantifies the pressure effect on the cosmic ray intensity, changes with the geomagnetic cutoff rigidity ( R C ), which quantifies the minimal rigidity/energy that a primary particle needs to reach a given location in a chosen direction. To do that, we used data recorded between January 2008 to December 2016 by several neutron monitors around the globe with R C from 0.1 to 8.3 GV. We experimentally obtained β in two ways: (I) the typical one, which does not explicitly consider isotropic variations unrelated to the pressure effect; and (II) one that considers such variations by using coupling coefficients and a reference neutron monitor station. Like other works, we found that the pressure effect seems to present a logarithmic relation with the cutoff rigidity when we estimate β through the typical method used. On the other hand, we found that the pressure effect linearly decreases with the cutoff rigidity when considering an adjustment in this typical method to eliminate external isotropic variations. This linear relation appears to not change accordingly to the reference monitor chosen. These results enhance our knowledge of how the pressure effect globally acts on the cosmic ray intensity observed at ground level and, consequently, improves future analysis about global changes in the cosmic ray flux related to space weather phenomena.

Seasonal Variation of Cosmic Ray Intensity Observed by the Oulu Neutron Monitor

Muons and neutrons are representative secondary particles that are generated by interactions between primary cosmic ray particles (mostly protons) and the nuclei of atmospheric gas compounds. Previous studies reported that muons experience seasonal variations because of the meteorological effects of temperature. The intensity of neutrons has a typical modulation with various periods and reasons, such as diurnal and solar variation or transient events. This paper reports that cosmic ray particles, which were observed by neutron monitors, have seasonal variations using the daily data at the Oulu neutron monitor. To eliminate the effects of solar activity across time, the daily data were normalized by two different transformations: transformations with respect to the grand mean and yearly mean. The data after transformation with respect to the yearly mean showed more statistical stability and clear seasonal variations. On the other hand, it is difficult to determine if the seasonal variation results from terrestrial effects, such as meteorological factors, or extraterrestrial effects, such as the position of the Earth in its orbit of revolution.

A Study of Variations of Galactic Cosmic-Ray Intensity Based on a Hybrid Data-processing Method

Abstract The low-energy cosmic-ray (CR) fluxes measured by space-borne instruments are generally considered to consist of gradually changing galactic CRs (GCRs) and short-lived solar energetic particles (SEPs). The SEP events cause sharp and ephemeral increases in the time profile of CR observations, with a higher occurrence rate in solar maximum. It is necessary to eliminate such spikes and obtain the pure GCR component while studying the modulation of GCRs in both short and long timescales. A hybrid data-processing method based on spike detection and time series analysis techniques is developed to remove the spikes and decompose the GCR data observed by the Interplanetary Monitoring Platform 8 into the long-term variation trend and the 27 day variation components. With the hybrid data-processing method, the 11 yr and 27 day variations in the intensity of low-energy GCRs can be studied systematically. Using the fitted trend component, the time lag in the solar modulation of low-energy GCRs is studied, and the results show that the time lag is both epoch and energy dependent. The obtained 27 day variation component is anticorrelated with the changes in solar wind velocity even during solar maximum. Implementing the running Fourier series fit procedure, the 27 day variation amplitude of the proton flux is computed. It is found that the yearly averaged values clearly show 11 and 22 yr variation cycles. In addition, the energy spectrum of the 27 day variation amplitude is softer in the A < 0 solar minimum than that in the A > 0 solar minimum.

Effects of solar activity on production rates of short‐lived cosmogenic radionuclides

AbstractThe solar activity can be quantified by solar modulation parameter Φ that affects the heliospheric magnetic field. This activity influences the intensity of the galactic cosmic ray (GCR) particle flux within the solar system, and consequently, the differential primary particle spectra depend on the solar modulation parameter Φ (MeV). The modulation parameter Φ shows spatial and temporal variations (Leya and Masarik 2009). Some of the solar activity variations are cyclic and result in measurable effects as for example the 11‐year solar cycle. Variations in solar activity only induce small effects on the production of long‐lived cosmogenic radionuclides. This is due to the fact that activities measured in meteorites usually correspond to saturation values and represent long‐term average values. Long‐lived radionuclides often require millions of years of irradiation by GCR to reach saturation and therefore activity cycles average out. In contrast, one can expect strongly pronounced variations for saturation values caused by primary flux intensity variations, if short‐lived radionuclides with half‐lives ranging from days to a few years are investigated. Short‐lived cosmogenic nuclides were the subject of many experimental and theoretical investigations (e.g., Evans et al. 1982; Spergel et al. 1986; Neumann et al. 1997; Komura et al. 2002; Laubenstein et al. 2012). The aim of this work is to develop formulae for calculating production rates of radionuclides with short half‐life, taking into account temporal variations in the primary cosmic ray intensity. The developed formulae were applied to the Kosice and Chelyabinsk meteorites. The results for the Košice meteorite were already published (Povinec et al. 2015). Here, we give a full explanation of underlying model.

Effect of Thunderstorm Electric Field on the Cosmic Ray Secondary Particle Energy at LHAASO

The Large High Altitude Air Shower Observatory (LHAASO) is located in Daocheng, Sichuan. Featured with frequent thunderstorms in summer seasons, it is beneficial to study the influence of atmospheric electric field on cosmic rays during thunderstorms. In this paper, Monte-Carlo simulations are performed to study the effect of thunderstorm electric field on the cosmic ray secondary electron energy at LHAASO. The energy distribution of electrons changes under the action of electric field. In the low energy region, the total number of electrons increases significantly, while at high energies, it does not change obviously. In the electric field of 1700V·cm−1 (above the critical field of the Relativistic Runaway Electron Avalanche (RREA) process), the electrons with an energy less than 120MeV can be accelerated. When the energy is below 60MeV, the number of electrons increases exponentially with an amplitude up to about 2252%. It is consistent with the theory of RREA. When the electric field strength is 1000V·cm−1 (below the threshold of the RREA process), the electrons with an energy less than 70MeV are accelerated, and their number increases significantly, but the increase (about 86%) is far lower than that of the critical field of the RREA process. The physical mechanism for accelerating the cosmic ray secondary particles by the thunderstorm electric field is discussed in the case when the electric field is less than the runaway electric field. These results may provide important information for studying the variations of cosmic ray intensity on the LHAASO detection surface during thunderstorms.

Responses and Periodic Variations of Cosmic Ray Intensity and Solar Wind Speed to Sunspot Numbers

To investigate the periodic behaviour and relationship of sunspot numbers with cosmic ray intensity and solar wind speed, we present analysis from daily data generated from 1995 January to 2018 December. Cross-correlation and wavelet transform tools were employed to carry out the investigation. The analyses confirmed that the cosmic ray intensity correlates negatively with the sunspot numbers, exhibiting an asynchronous phase relationship with a strong negative correlation. The trend in cosmic ray intensity indicates that it undergoes the 11-year modulation that mainly depends on the solar activity in the heliosphere. On the other hand, the solar wind speed neither shows a clear phase relationship nor correlates with the sunspot numbers but shows a wide range of periodicities that could possibly be connected to the pattern of coronal hole configuration. A number of short and midterm variations were also observed from the wavelet analysis, i.e., 64–128 and 128–256 days for the cosmic ray intensity, 4–8, 32–64, 128–256, and 256–512 days for the solar wind speed, and 16–32, 32–64, 128–256, and 256–512 days for the sunspot numbers.