scholarly journals Time-dependent solar modulation of cosmic rays from solar minimum to solar maximum

2019 ◽  
Vol 100 (6) ◽  
Author(s):  
Bing-Bing Wang ◽  
Xiao-Jun Bi ◽  
Kun Fang ◽  
Su-Jie Lin ◽  
Peng-Fei Yin
Keyword(s):  
Cosmic Rays ◽  
Solar Minimum ◽  
Solar Maximum ◽  
Time Dependent ◽  
Solar Modulation

scholarly journals Latitudinal and radial variation of >2 GeV/n protons and alpha-particles at solar maximum: ULYSSES COSPIN/KET and neutron monitor network observations

2003 ◽  
Vol 21 (6) ◽  
pp. 1295-1302 ◽  
Author(s):  
A. V. Belov ◽  
E. A. Eroshenko ◽  
B. Heber ◽  
V. G. Yanke ◽  
A. Raviart ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Cosmic Rays ◽  
Neutron Monitor ◽  
Solar Minimum ◽  
Latitudinal Gradient ◽  
Solar Maximum ◽  
Cosmic Ray ◽  
Galactic Cosmic Rays ◽  
Alpha Particles ◽  
Polar Regions

Abstract. Ulysses, launched in October 1990, began its second out-of-ecliptic orbit in September 1997. In 2000/2001 the spacecraft passed from the south to the north polar regions of the Sun in the inner heliosphere. In contrast to the first rapid pole to pole passage in 1994/1995 close to solar minimum, Ulysses experiences now solar maximum conditions. The Kiel Electron Telescope (KET) measures also protons and alpha-particles in the energy range from 5 MeV/n to >2 GeV/n. To derive radial and latitudinal gradients for >2 GeV/n protons and alpha-particles, data from the Chicago instrument on board IMP-8 and the neutron monitor network have been used to determine the corresponding time profiles at Earth. We obtain a spatial distribution at solar maximum which differs greatly from the solar minimum distribution. A steady-state approximation, which was characterized by a small radial and significant latitudinal gradient at solar minimum, was interchanged with a highly variable one with a large radial and a small – consistent with zero – latitudinal gradient. A significant deviation from a spherically symmetric cosmic ray distribution following the reversal of the solar magnetic field in 2000/2001 has not been observed yet. A small deviation has only been observed at northern polar regions, showing an excess of particles instead of the expected depression. This indicates that the reconfiguration of the heliospheric magnetic field, caused by the reappearance of the northern polar coronal hole, starts dominating the modulation of galactic cosmic rays already at solar maximum.Key words. Interplanetary physics (cosmic rays; energetic particles) – Space plasma physics (charged particle motion and acceleration)

Solar modulation of galactic cosmic rays near solar minimum (1965)

1968 ◽  
Vol 46 (10) ◽  
pp. S887-S891 ◽  
Author(s):  
V. K. Balasubrahmanyan ◽  
D. E. Hagge ◽  
F. B. McDonald
Keyword(s):  
Cosmic Rays ◽  
Solar Minimum ◽  
Intensity Variation ◽  
Cosmic Ray ◽  
Galactic Cosmic Rays ◽  
Solar Modulation ◽  
Time Behavior ◽  
Cosmic Ray Intensity ◽  
Radial Gradient

The results of the continuous monitoring of the intensity of cosmic rays (of energy > 50 MeV) with identical G-M counter telescopes flown in satellites IMP I, II, and III and OGO-I are presented along with the differential spectrum studies obtained from balloon flights at Fort Churchill and from satellites. A comparison of the time behavior of the G-M counter data with Deep River neutron monitor data suggests the presence of a "hysteresis" type of behavior due to spectral changes occurring near solar minimum. The existence of this "hysteresis" suggests that the radial gradient of cosmic rays near the earth could be much smaller than the ~ 10%/AU obtained by O'Gallagher and Simpson (1967) and O'Gallagher (1967) at higher energies. The long-term intensity variation of cosmic rays seems to follow the Ap index rather closely in phase, in contrast to sunspot numbers which display a pronounced phase difference with cosmic-ray intensity. The differential spectra of protons and He nuclei have been analyzed in terms of two different models for the propagation in the interplanetary medium. The modulations indicated by the present data seem to disagree with a diffusion coefficient proportional to βR where β and R are the velocity and rigidity of the particle respectively (Jokipii 1966).

scholarly journals Cosmic rays, aerosol formation and cloud-condensation nuclei: sensitivities to model uncertainties

2011 ◽  
Vol 11 (8) ◽  
pp. 4001-4013 ◽  
Author(s):  
E. J. Snow-Kropla ◽  
J. R. Pierce ◽  
D. M. Westervelt ◽  
W. Trivitayanurak
Keyword(s):  
Cosmic Rays ◽  
Solar Minimum ◽  
Solar Maximum ◽  
Cloud Condensation Nuclei ◽  
Cosmic Ray ◽  
Organic Aerosol ◽  
Test Cases ◽  
Primary Emissions ◽  
Cosmic Ray Flux ◽  
Aerosol Properties

Abstract. The flux of cosmic rays to the atmosphere has been reported to correlate with cloud and aerosol properties. One proposed mechanism for these correlations is the "ion-aerosol clear-air" mechanism where the cosmic rays modulate atmospheric ion concentrations, ion-induced nucleation of aerosols and cloud condensation nuclei (CCN) concentrations. We use a global chemical transport model with online aerosol microphysics to explore the dependence of CCN concentrations on the cosmic-ray flux. Expanding upon previous work, we test the sensitivity of the cosmic-ray/CCN connection to several uncertain parameters in the model including primary emissions, Secondary Organic Aerosol (SOA) condensation and charge-enhanced condensational growth. The sensitivity of CCN to cosmic rays increases when simulations are run with decreased primary emissions, but show location-dependent behavior from increased amounts of secondary organic aerosol and charge-enhanced growth. For all test cases, the change in the concentration of particles larger than 80 nm between solar minimum (high cosmic ray flux) and solar maximum (low cosmic ray flux) simulations is less than 0.2 %. The change in the total number of particles larger than 10 nm was larger, but always less than 1 %. The simulated change in the column-integrated Ångström exponent was negligible for all test cases. Additionally, we test the predicted aerosol sensitivity to week-long Forbush decreases of cosmic rays and find that the maximum change in aerosol properties for these cases is similar to steady-state aerosol differences between the solar maximum and solar minimum. These results provide evidence that the effect of cosmic rays on CCN and clouds through the ion-aerosol clear-sky mechanism is limited by dampening from aerosol processes.

scholarly journals On The Occurrence of Historical Pandemics During The Grand Solar Minima

2020 ◽  
Vol 2 (4) ◽  
Author(s):  
C. E. Navia
Keyword(s):  
Cosmic Rays ◽  
Cross Section ◽  
Neutron Capture ◽  
Solar Minimum ◽  
Inverse Relationship ◽  
Viral Proteins ◽  
Antigenic Drift ◽  
Solar Modulation ◽  
Antigenic Shift ◽  
New Type

The occurrence of viral pandemics depends on several factors, including their stochasticity, and the prediction may not be possible. However, we show that the historical register of pandemics coincides with the epoch of the last seven grand solar minima of the Holocene era. We also included those more recent, and some pandemics incidence forecasts for the coming years, with the probable advent of a new Dalton-like solar minimum with onset in 2006. Taking into account that cosmic-rays and consequently the neutrons produced by them in the atmosphere are in an inverse relationship with the solar activity. We show the possibility of obtention the pandemics occurrence rates considering that they are due to mutations induced by the neutron capture upon the presence of hydrogen in the viral proteins, producing radical changes, an “antigenic-shift”, forming a new type of viral strains. Since the cross-section of neutron capture is small, the occurrence of an antigenic-shift requires a substantial increase in the flow of thermal neutrons, and this is more feasible during the epochs of the grand solar minima when the cosmic-rays fluence is highest. On the other hand, the rate of occurrence of most common viral outbreaks (epidemics) suggests a link with the scattering of neutrons and other secondary cosmic rays, causing small changes, an “antigenic-drift”. In addition to being influenced by seasonal conditions, we also show the solar modulation antigenic-drifts by the 11-year solar cycle. We present details of these observations.

ULYSSES: EXPLORING THE HELIOSPHERE IN FOUR DIMENSIONS

2005 ◽  
Vol 20 (29) ◽  
pp. 6654-6657
Author(s):  
RICHARD G. MARSDEN
Keyword(s):  
Cosmic Rays ◽  
Solar Minimum ◽  
Solar Maximum ◽  
Energetic Particles ◽  
The Sun ◽  
Four Dimensions ◽  
3 Dimensional ◽  
Spatial Dimensions

Ulysses is the first spacecraft ever to fly over the poles of the sun. Its primary goal is to explore the heliosphere in four dimensions: three spatial dimensions, and time. An overview of some of the recent results from the mission will be presented. Particular emphasis will be given to the changes occurring in the 3-dimensional heliosphere from solar minimum to solar maximum, and their effects on energetic particles and cosmic rays.

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