Multi-parametric effect of solar activity on cosmic rays

Time evolution of cosmic-ray intensity and solar flare index at the maximum phase of cycles 21 and 22

Elucidation of some solar parameters observed during solar cycles 21–24

Modulated of cosmic rays and their propagation in the heliosphere by the effect of the large-scale structure of the interplanetary medium. Its comparison of the variations of cosmic Neutron monitor intensity with variation of sunspot number, geomagnetic indices, solar wind velocity (V), interplanetary magnetic field (B), near the Earth for the period solar cycle 24 .it has been accessible as a likely correlation among them. we calculated the yearly average cosmic ray counts detected with Oulu NM. It is significantly undesirable correlation have been detected between interplanetary magnetic field (B), and cosmic ray intensity earlier the solar cycle 24. The sunspot number and solar wind velocity has a noble positive relationship with cosmic ray intensity during solar cycle 21, but it indications weak association before through solar cycle 24. The interplanetary magnetic field, B displays a weak negative association with cosmic rays for the solar cycle, while B shows a noble anti-correlation for the before during solar cycle 24 through cosmic ray intensity. The cosmic ray intensity displays decent positive correlation through interplanetary causes time, and geomagnetic indices (Dst) index forgoing the solar cycle 24 , whereas shows weak correlation for formerly the cycle 24.

Hysteresis, time lag, and relation between solar activity and cosmic rays during solar cycle 24

Abstract. We analyse phase lags between the 11-year variations of three records: the semi-annual oscillation of the length of day (LOD), the solar activity (SA) and the cosmic ray intensity (CRI). The analysis was done for solar cycles 20–23. Observed relationships between LOD, CRI and SA are discussed separately for even and odd solar cycles. Phase lags were calculated using different methods (comparison of maximal points of cycles, maximal correlation coefficient, line of synchronization of cross-recurrence plots). We have found different phase lags between SA and CRI for even and odd solar cycles, confirming previous studies. The evolution of phase lags between SA and LOD as well as between CRI and LOD shows a positive trend with additional variations of phase lag values. For solar cycle 20, phase lags between SA and CRI, between SA and LOD, and between CRI and LOD were found to be negative. Overall, our study suggests that, if anything, the length of day could be influenced by solar irradiance rather than by cosmic rays.

This study investigated the relationship between the most influential solar and interplanetary plasma parameters and cosmic ray modulation. A principal component analysis (PCA) method was used. The variations of the cosmic ray intensity were obtained at 6 different locations with different latitudes and cutoff rigidities. These stations were located at mid- to high latitudes (SOPO, OULU, and NEWK), while the remaining three were located at low latitudes (MXCO, TSMB, and PSNM). A parameter ranking based on PCA confirmed that sunspot number, interplanetary magnetic field (IMF) magnitude, heliospheric current sheet (HCS) tilt, halo coronal mass ejection (CME) velocity, Bz, and proton density have the highest link with the modulation of cosmic ray intensity. Meanwhile, the PCA analysis at low latitudes revealed that the cone angle and the magnetic field components By and Bx along the y- and x-axes, the mean magnetic field of the Sun, the HCS tilt, and the IMF magnitude exert the greatest correlation on the cosmic ray intensity modulation at this station. The correlation between the analyzed parameters and cosmic ray modulation appears to vary with latitude.

Spectral analysis of solar and geomagnetic parameters as well as of cosmic-ray intensity was performed aiming to identify possible new periodicities and confirm the well-known ones. Specifically, short-, mid-, and long-term periodicities of these parameters such as sunspot number, Bz-component of the interplanetary magnetic field, geomagnetic Ap index, and cosmic-ray intensity over the time period 1965 – 2018, covering five solar cycles from Cycles 20 to 24, are presented. For this purpose, two different techniques, fast Fourier transformation and wavelet analysis, have been used in order to ensure accuracy in the frequency values and also their localization in the time series. The periodicities resulting from our comprehensive study, including the well-known 11-year and 27-day periods, the harmonics of the 5.5-year and of the 6-, 9-, and 13.9-day periods, respectively, and the ≈ 1.3-year and 1.7-year periods, were found in all of the above parameters except for the Bz-component of the interplanetary magnetic field. New periodicities such as the ≈ 10-month period for sunspot number and cosmic-ray intensity and the ≈ 3-year period for sunspot number, Ap index, and cosmic-ray intensity, were also determined. Furthermore, the newly introduced splitting of the 27-day periodicity into two adjacent peaks was confirmed in the Fourier spectra of the interplanetary magnetic field and the geomagnetic Ap index. It was concluded that several common periodicities appear in solar activity: the Ap index, and the cosmic-ray intensity. This result, in association with the fact that the spectral behavior of geomagnetic-activity parameters, provides invaluable information about the physical processes involved, and indicates that the Ap index might be used as a suitable index for space-weather forecasting.

Solar, geomagnetic and cosmic ray intensity changes, preceding the cyclone appearances around Mexico

Changed relation between sunspot numbers, solar UV/EUV radiation and TSI during the declining phase of solar cycle 23

Solar energetic particle (SEP) events are related to flares and coronal mass ejections (CMEs). This work is a new investigation of statistical relationships between SEP peak intensities – deka-MeV protons and near-relativistic electrons – and characteristic quantities of the associated solar activity. We consider the speed of the CME and quantities describing the flare-related energy release: peak flux and fluence of soft X-ray (SXR) emission and the fluence of microwave emission. The sample comprises 38 SEP events associated with strong SXR bursts (classes M and X) in the western solar hemisphere between 1997 and 2006, in which the flare-related particle acceleration was accompanied by radio bursts indicating electron escape into the interplanetary space. The main distinction of the present statistical analysis from earlier work is that in addition to the classical Pearson correlation coefficient, the partial correlation coefficients are calculated to remove the correlation effects between the solar parameters themselves. The classical correlation analysis shows the usual picture of correlations with broad scatter between SEP peak intensities and the different parameters of solar activity and strong correlations between the solar activity parameters themselves. The partial correlation analysis shows that the only parameters that significantly affect the SEP intensity are the CME speed and the SXR fluence. The SXR peak flux and the microwave fluence make no additional contribution. We conclude that these findings bring statistical evidence that both flare acceleration and CME shock acceleration contribute to the deka-MeV proton and near-relativistic electron populations in large SEP events.

Quantitatively relating cosmic rays intensities from solar activity parameters based on structural equation modeling

Prediction of expected global climate change by forecasting of galactic cosmic ray intensity time variation in near future based on solar magnetic field data

Neutron monitor counting rates and solar wind velocity, interplanetary magnetic field, sunspot number and total solar irradiance measurements from 2013 to 2018 corresponding to the end of solar maximum and the decreasing phase of the Solar Cycle 24 have been used. The main objective is to check whether the periodicities observed in the cosmic rays are affected by the magnetic rigidity or the height at which the neutron monitors are placed. A Global Neutron Monitor (GNM) has been defined as representative of the neutron monitor global network. This GNM is constructed by averaging the counting rates of a set of selected neutron monitors. The selection process is based on the combination of three new data quality criteria, which are applied to neutron monitors in the Neutron Monitor Data Base giving a final pool of 22 selected neutron monitors. Morlet wavelet analysis is applied to the GNM and the selected solar activity parameters to find the common periodicities. Short-term periodicities of 13.5, 27, 48, 92, 132 and 298 days have been observed in cosmic ray intensity. A clear inverse relationship between rigidity and spectral power has been obtained for the 13.5-, 48-, 92-, 132-day periods. A not so clear but still observed direct relationship between the height of the neutron monitors and the spectral power for the 48-, 92-, 132-day periods has been also found. The periodicity of 92 days is the one which shows the highest dependence with rigidity cutoff and height. As far as we know, this is the first time that these dependencies are reported. We think that these observations could be explained by assuming some cosmic ray intensity energy dependence in such periodicities and a competitive effect between rigidity and height.

We reexamine the empirical relationship between the Sun's open magnetic flux and the cosmic-ray (CR) intensity over the solar cycle. The single parameter that correlates best with the inverted CR rate is found to be the nonaxisymmetric or longitudinally varying component of the total open flux, rather than the sunspot number or the rate of coronal mass ejections (CMEs). The nonaxisymmetric open flux in turn tracks the evolution of the Sun's equatorial dipole component, which is a function of both the strength and the longitudinal distribution of sunspot activity. Year-long peaks in the equatorial dipole strength coincide with steplike decreases in the CR intensity and with the formation of global merged interaction regions (GMIRs) in the outer heliosphere. During these periods, nonaxisymmetric open flux (in the form of low-latitude coronal holes) is created through the organized emergence of large active regions, resulting in the global injection of magnetic energy into the heliosphere. At the same time, strengthenings of the equatorial dipole are generally accompanied by large increases in the number of fast CMEs. Rotationally induced, compressional interactions between the nonaxisymmetric open flux, fast CMEs, and high-speed streams then give rise to outward-propagating diffusive barriers that extend over all longitudes and to a latitude (45°) again determined by the equatorial dipole strength.

A wavelet based analysis of cosmic rays modulation