Evidence from Galactic Cosmic Rays That the Sun Has Likely Entered A Secular Minimum in Solar Activity

Almost the whole increase in the cosmic-ray intensity in the stratosphere during the period of decreasing solar activity (1960–64) was composed of a number of individual events occurring at intervals of 6–12 months. This phenomenon is almost entirely due to the corresponding decrease of solar activity (according to the sunspot number).Several interesting cases were found when solar-activity decreases to a new stationary level took place rapidly (within several days). After such events the cosmic-ray intensity gradually increased to reach a stationary level over a period of about two months. The time, tst, during which the cosmic-ray intensity in interplanetary space (after the above-mentioned events on the sun) approaches a stationary value is about 40, 60, and 80 days according to observations in 1961, 1963, and 1964 respectively.Some results have been obtained on the large-scale magnetic "clouds" which modulate the galactic cosmic rays in interplanetary space: (a) The velocity of propagation of these magnetic clouds is [Formula: see text]. According to the data on u and tst the radius of the sphere around the sun, r, within which the cosmic rays are modulated depends little on solar activity and is equal to 10–15 AU. (b) The density of magnetic clouds in space is either independent of the distance to the sun or decreases less rapidly than the inverse square law suggested by conservation of clouds.[Formula: see text]

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Features of 27-day variations of galactic cosmic rays and of solar activity

Advances in Space Research ◽

10.1016/s0273-1177(99)00108-8 ◽

1999 ◽

Vol 23 (3) ◽

pp. 471-474 ◽

Cited By ~ 4

Author(s):

M.V Alania ◽

E.S Vernova ◽

M.I Tyasto ◽

D.G Baranov

Keyword(s):

Solar Activity ◽

Cosmic Rays ◽

Galactic Cosmic Rays

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Influence of supernovae, gamma-ray bursts, solar flares, and cosmic rays on the terrestrial environment

Global Catastrophic Risks ◽

10.1093/oso/9780198570509.003.0017 ◽

2008 ◽

Author(s):

Arnon Dar

Keyword(s):

Solar Activity ◽

Cosmic Rays ◽

Gamma Ray ◽

Cosmic Ray ◽

Gamma Ray Bursts ◽

The Sun ◽

Terrestrial Environment ◽

The Earth ◽

The Galaxy ◽

Threat To Life

Changes in the solar neighbourhood due to the motion of the sun in the Galaxy, solar evolution, and Galactic stellar evolution influence the terrestrial environment and expose life on the Earth to cosmic hazards. Such cosmic hazards include impact of near-Earth objects (NEOs), global climatic changes due to variations in solar activity and exposure of the Earth to very large fluxes of radiations and cosmic rays from Galactic supernova (SN) explosions and gamma-ray bursts (GRBs). Such cosmic hazards are of low probability, but their influence on the terrestrial environment and their catastrophic consequences, as evident from geological records, justify their detailed study, and the development of rational strategies, which may minimize their threat to life and to the survival of the human race on this planet. In this chapter I shall concentrate on threats to life from increased levels of radiation and cosmic ray (CR) flux that reach the atmosphere as a result of (1) changes in solar luminosity, (2) changes in the solar environment owing to the motion of the sun around the Galactic centre and in particular, owing to its passage through the spiral arms of the Galaxy, (3) the oscillatory displacement of the solar system perpendicular to the Galactic plane, (4) solar activity, (5) Galactic SN explosions, (6) GRBs, and (7) cosmic ray bursts (CRBs). The credibility of various cosmic threats will be tested by examining whether such events could have caused some of the major mass extinctions that took place on planet Earth and were documented relatively well in the geological records of the past 500 million years (Myr). A credible claim of a global threat to life from a change in global irradiation must first demonstrate that the anticipated change is larger than the periodical changes in irradiation caused by the motions of the Earth, to which terrestrial life has adjusted itself. Most of the energy of the sun is radiated in the visible range. The atmosphere is highly transparent to this visible light but is very opaque to almost all other bands of the electromagnetic spectrum except radio waves, whose production by the sun is rather small.

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Effects of solar activity and galactic cosmic ray cycles on the modulation of the annual average temperature at two sites in southern Brazil

Annales Geophysicae ◽

10.5194/angeo-36-555-2018 ◽

2018 ◽

Vol 36 (2) ◽

pp. 555-564 ◽

Cited By ~ 4

Author(s):

Everton Frigo ◽

Francesco Antonelli ◽

Djeniffer S. S. da Silva ◽

Pedro C. M. Lima ◽

Igor I. G. Pacca ◽

...

Keyword(s):

Solar Activity ◽

Cosmic Rays ◽

Cosmic Ray ◽

Galactic Cosmic Rays ◽

Southern Brazil ◽

Solar Cycles ◽

Annual Average ◽

Average Temperature ◽

Weather Stations ◽

Annual Average Temperature

Abstract. Quasi-periodic variations in solar activity and galactic cosmic rays (GCRs) on decadal and bidecadal timescales have been suggested as a climate forcing mechanism for many regions on Earth. One of these regions is southern Brazil, where the lowest values during the last century were observed for the total geomagnetic field intensity at the Earth's surface. These low values are due to the passage of the center of the South Atlantic Magnetic Anomaly (SAMA), which crosses the Brazilian territory from east to west following a latitude of ∼ 26∘. In areas with low geomagnetic intensity, such as the SAMA, the incidence of GCRs is increased. Consequently, possible climatic effects related to the GCRs tend to be maximized in this region. In this work, we investigate the relationship between the ∼ 11-year and ∼ 22-year cycles that are related to solar activity and GCRs and the annual average temperature recorded between 1936 and 2014 at two weather stations, both located near a latitude of 26∘ S but at different longitudes. The first of these stations (Torres – TOR) is located in the coastal region, and the other (Iraí – IRA) is located in the interior, around 450 km from the Atlantic Ocean. Sunspot data and the solar modulation potential for cosmic rays were used as proxies for the solar activity and the GCRs, respectively. Our investigation of the influence of decadal and bidecadal cycles in temperature data was carried out using the wavelet transform coherence (WTC) spectrum. The results indicate that periodicities of 11 years may have continuously modulated the climate at TOR via a nonlinear mechanism, while at IRA, the effects of this 11-year modulation period were intermittent. Four temperature maxima, separated by around 20 years, were detected in the same years at both weather stations. These temperature maxima are almost coincident with the maxima of the odd solar cycles. Furthermore, these maxima occur after transitions from even to odd solar cycles, that is, after some years of intense GCR flux. The obtained results offer indirect mathematical evidence that solar activity and GCR variations contributed to climatic changes in southern Brazil during the last century. A comparison of the results obtained for the two weather stations indicates that the SAMA also contributes indirectly to these temperature variations. The contribution of other mechanisms also related to solar activity cannot be excluded. Keywords. Meteorology and atmospheric dynamics (climatology)

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Cosmic-ray propagation around the Sun: investigating the influence of the solar magnetic field on the cosmic-ray Sun shadow

Astronomy and Astrophysics ◽

10.1051/0004-6361/201936306 ◽

2020 ◽

Vol 633 ◽

pp. A83

Author(s):

J. Becker Tjus ◽

P. Desiati ◽

N. Döpper ◽

H. Fichtner ◽

J. Kleimann ◽

...

Keyword(s):

Magnetic Field ◽

Solar Activity ◽

Solar Cycle ◽

Cosmic Rays ◽

Solar Magnetic Field ◽

Cosmic Ray ◽

High Energy ◽

High Solar Activity ◽

The Sun ◽

Theoretical Understanding

The cosmic-ray Sun shadow, which is caused by high-energy charged cosmic rays being blocked and deflected by the Sun and its magnetic field, has been observed by various experiments, such as Argo-YBJ, Tibet, HAWC, and IceCube. Most notably, the shadow’s size and depth was recently shown to correlate with the 11-year solar cycle. The interpretation of such measurements, which help to bridge the gap between solar physics and high-energy particle astrophysics, requires a solid theoretical understanding of cosmic-ray propagation in the coronal magnetic field. It is the aim of this paper to establish theoretical predictions for the cosmic-ray Sun shadow in order to identify observables that can be used to study this link in more detail. To determine the cosmic-ray Sun shadow, we numerically compute trajectories of charged cosmic rays in the energy range of 5−316 TeV for five different mass numbers. We present and analyze the resulting shadow images for protons and iron, as well as for typically measured cosmic-ray compositions. We confirm the observationally established correlation between the magnitude of the shadowing effect and both the mean sunspot number and the polarity of the magnetic field during the solar cycle. We also show that during low solar activity, the Sun’s shadow behaves similarly to that of a dipole, for which we find a non-monotonous dependence on energy. In particular, the shadow can become significantly more pronounced than the geometrical disk expected for a totally unmagnetized Sun. For times of high solar activity, we instead predict the shadow to depend monotonously on energy and to be generally weaker than the geometrical shadow for all tested energies. These effects should become visible in energy-resolved measurements of the Sun shadow, and may in the future become an independent measure for the level of disorder in the solar magnetic field.

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The change in the energy spectrum of galactic cosmic rays over the 11-year solar activity cycle

Canadian Journal of Physics ◽

10.1139/p68-385 ◽

1968 ◽

Vol 46 (10) ◽

pp. S927-S929

Author(s):

Yu. Stozhkov ◽

T. N. Charakhchyan

Keyword(s):

Diffusion Coefficient ◽

Solar Activity ◽

Energy Spectrum ◽

Cosmic Rays ◽

Cosmic Ray ◽

Activity Cycle ◽

Solar Activity Cycle ◽

Galactic Cosmic Rays ◽

Ray Diffusion

The energy spectrum of galactic cosmic rays has been investigated for various periods of the solar activity. In the framework of commonly used ideas about the mechanism of the 11-year variation according to Parker the dependence of the cosmic-ray diffusion coefficient, D, on the particle rigidity, P, was determined. For the form D ≈ vpα the parameter α is found to change during the cycle of the solar activity.[Formula: see text]

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The circumpolar vortex as a cause for time variations in the effects of solar activity and galactic cosmic rays on the circulation of the lower atmosphere

Bulletin of the Russian Academy of Sciences Physics ◽

10.3103/s1062873813050523 ◽

2013 ◽

Vol 77 (5) ◽

pp. 590-592

Author(s):

S. V. Veretenenko ◽

M. G. Ogurtsov

Keyword(s):

Solar Activity ◽

Cosmic Rays ◽

Galactic Cosmic Rays ◽

Lower Atmosphere ◽

Circumpolar Vortex ◽

Time Variations

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Quasi-periodic changes in the 3D solar anisotropy of Galactic cosmic rays for 1965–2014

Astronomy and Astrophysics ◽

10.1051/0004-6361/201731697 ◽

2017 ◽

Vol 609 ◽

pp. A32 ◽

Cited By ~ 2

Author(s):

R. Modzelewska ◽

M. V. Alania

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Solar Activity ◽

Solar Cycle ◽

Cosmic Rays ◽

Ecliptic Plane ◽

Galactic Cosmic Rays ◽

Magnetic Cycle ◽

The North ◽

Solar Magnetic Cycle

Aims. We study features of the 3D solar anisotropy of Galactic cosmic rays (GCR) for 1965−2014 (almost five solar cycles, cycles 20−24). We analyze the 27-day variations of the 2D GCR anisotropy in the ecliptic plane and the north-south anisotropy normal to the ecliptic plane. We study the dependence of the 27-day variation of the 3D GCR anisotropy on the solar cycle and solar magnetic cycle. We demonstrate that the 27-day variations of the GCR intensity and anisotropy can be used as an important tool to study solar wind, solar activity, and heliosphere. Methods. We used the components Ar, Aϕ and At of the 3D GCR anisotropy that were found based on hourly data of neutron monitors (NMs) and muon telescopes (MTs) using the harmonic analyses and spectrographic methods. We corrected the 2D diurnal (~24-h) variation of the GCR intensity for the influence of the Earth magnetic field. We derived the north-south component of the GCR anisotropy based on the GG index, which is calculated as the difference in GCR intensities of the Nagoya multidirectional MTs. Results. We show that the behavior of the 27-day variation of the 3D anisotropy verifies a stable long-lived active heliolongitude on the Sun. This illustrates the usefulness of the 27-day variation of the GCR anisotropy as a unique proxy to study solar wind, solar activity, and heliosphere. We distinguish a tendency of the 22-yr changes in amplitude of the 27-day variation of the 2D anisotropy that is connected with the solar magnetic cycle. We demonstrate that the amplitudes of the 27-day variation of the north-south component of the anisotropy vary with the 11-yr solar cycle, but a dependence of the solar magnetic polarity can hardly be recognized. We show that the 27-day recurrences of the GG index and the At component are highly positively correlated, and both are highly correlated with the By component of the heliospheric magnetic field.

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The Drugs and Natural Antioxidants as the Components of Anti-radiation Countermeasures during Cosmic Flights

Medical Radiology and radiation safety ◽

10.12737/article_59b10b5ea417a6.00174966 ◽

2017 ◽

pp. 66-73 ◽

Cited By ~ 2

Author(s):

И. Ушаков ◽

I. Ushakov ◽

М. Васин ◽

M. Vasin

Keyword(s):

Solar Activity ◽

Cosmic Rays ◽

Radiation Effects ◽

High Energy ◽

Galactic Cosmic Rays ◽

Stress Factors ◽

Solar Cosmic Rays ◽

Post Radiation ◽

The Impact

Radiation situation for cosmonauts over long-term cosmic flights is caused by low-rate radiation of galactic cosmic rays and solar cosmic rays consisting of high-energy proton as well as heavy particles (Z>10) within 1-2 % that is exclusively a threat of stochastic radiation effects (small increase of cancer risk and decrease of mean life span) for men. During interplanetary expedition periods the small probability of raised solar activity there is a threat of exposure to astronauts at doses that cause deterministic radiation effects leading to the development of the disease as a clinical manifestation of radiation injuries,. In a similar scenario it is necessary to have available to cosmic ship anti-radiation countermeasures for cosmonaut protection. Among radioprotective equipment can be provided with radiation protective agents and partial shielding of body separate section providing the best condition for post-radiation repair of radiosensitive body tissues. Preparation B-190 (indralin) is the most perspective from a small numbers of other radioprotectors permitting for men administration. Besides high radioprotective efficacy and large broadness of protective action B-190 is well tolerated including the impact of extrem flight factors. Antiemetic agent latran (ondansetron) is most interesting among preparation for prophylaxis and reduction of prodromal radiation reaction. To accelerate post-radiation hematopoietic recovery after raised solar activity an administration of radiomitigators (riboxin et al.) is substantiated. Neupomax (neupogen) is recommended as a preparation for pathogenesis therapy of acute radiation syndrome. Possible consequences of long-term cosmic voyages for oxidative stress development are taken into consideration. On their basis of nNatural antioxidants, preparations and nutrients radiomodulators, fully qualitative nutrition including vegetable food enriched flavonoids, vitamins C, E and carotene potentially prevent a shorten of cosmonaut biological age induced by solar cosmic rays and galactic cosmic rays and stress factors of long-term cosmic voyages. Radiomodulators are low and non-toxic and have not side effects in recommended doses. Their radioprotective effect is directly induced by adaption reaction on cellular and organismic levels through gene expression modulation and in that way the increase of non-specific body tolerance. The implementation of radiomodulator action is possible through hormesis mechanism.

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