Figure 8 - uploaded by Nir J. Shaviv
Content may be subject to copyright.
Cosmic ray flux measured by the Hermanus NM (at sea-level with a cut-off rigidity of 4.6 GV) in South Africa. Note the 11-year and 22-year cycles. 

Cosmic ray flux measured by the Hermanus NM (at sea-level with a cut-off rigidity of 4.6 GV) in South Africa. Note the 11-year and 22-year cycles. 

Source publication
Article
Full-text available
In recent years the variability of the cosmic ray flux has become one of the main issues interpreting cosmogenic elements and especially their connection with climate. In this review, an interdisciplinary team of scientists brings together our knowledge of the evolution and modulation of the cosmic ray flux from its origin in the Milky Way, during...

Contexts in source publication

Context 1
... monitors have been remarkably reliable, with good statistics, over five full 11-year cycles. An example of this 11-year cosmic ray cycle is shown in Figure 8, which is the flux measured by the Hermanus NM in South Africa. The intensity is corrected for atmospheric pressure to get rid of seasonal and daily variations. ...
Context 2
... Figure 8 another important cycle, the 22-year cycle, is shown. This cycle is directly related to the reversal of the solar magnetic field during each period of extreme solar activity and is revealed in CR modulation as the alternating flat and sharp profiles of consecutive solar minimum modulation epochs when the CR intensity becomes a maximum (minimum modulation). ...
Context 3
... usually merge as they propagate outwards to form various types of interaction regions, the largest ones are known as global merged interaction regions -GMIRs ( Burlaga et al., 1993). Such a GMIR caused the very large cosmic ray decrease in 1991, shown in Figure 8. They are related to what happened to the solar magnetic field at some earlier stage and are linked to coronal mass ejections (CMEs), which are always prominent with increased solar activity but dissipate completely during solar minimum. ...
Context 4
... to consider the high levels of sunspot activity for the last few 11-year cycles as unprecedented is still inconclusive. From Figure 8 follows that the maximum levels of CRs seem to gradually decrease. ...
Context 5
... and curvature drift is the fourth major mechanism, and gets prominent during solar minimum conditions when the magnetic field becomes globally well structured. In the A > 0 drift cycle (see Figure 8) the northern field points away from the Sun, consequently positively charged particles drift mainly from high heliolatitudes toward the equatorial plane and outward primarily along the current sheet, giving the typical flat intensity-time profiles. The current (neutral) sheet separates the field in two hemispheres and becomes progressively inclined and wavy, due to solar rotation, with increasing solar activity (Smith, 2001). ...
Context 6
... 22-year cycle, originating from the reversal of the solar magnetic field roughly every 11 years, is superimposed on the 11-year cycle with an amplitude less than 50% of the 11-year cycle. As shown in Figure 8, the NM intensity-time profiles exhibit the expected peak-like shapes around the solar minima of 1965 and 1987 (A < 0), while around 1954, 1976 and 1998 (A > 0) they were conspicuously flatter. Shortly after the extraordinary flat profile around 1976 was observed, two research groups, in Arizona (Jokipii et al., 1977) and in South Africa, quickly recognized that gradient and curvature drifts, together with current sheet drifts, could explain these features (Potgieter and Moraal, 1985, and references therein). ...
Context 7
... the cosmic ray intensity at NM energies are higher in A < 0 cycles at solar minimum than in the A > 0 cycles -see Figure 8 -the situation is reversed for lower energies e.g., for 200 MeV protons, confirmed by spacecraft observa- tions. This requires the differential spectra of consecutive solar minima to cross at energies between 1 and 5 GeV ( Reinecke and Potgieter, 1994). ...
Context 8
... steady-state model is formulated in a frame corotating with the Sun. Figure 18 gives a comparison of the spectra at the Earth as well as the latitudinal gradients resulting for the Parker field and a hybrid field having Fisk-and Parker-field properties. ...
Context 9
... cosmic ray flux dependence on the geomagnetic latitude was already observed shortly after World War II. Figure 28 represents the variation of the flux of fast neutrons in the atmosphere with geomagnetic latitude measured by Simpson (1951Simpson ( , 2000. ...
Context 10
... external geomagnetic field, also called the magnetospheric magnetic field, refers to the magnetic field induced by the magne- tospheric currents. The International Geomagnetic Reference Field (IGRF) model represents the most frequently used model of the Earth's internal magnetic field for Figure 28. Geomagnetic latitude dependence of fast neutrons as observed by Simpson (1951), taken from Simpson (2000). ...
Context 11
... dependent changes of the production rate are caused mainly by variations of the geomagnetic field intensity and the solar activity. From measurements of cosmo- genic radionuclides with different half-lives and different irradiation histories in meteorites, the average galactic CRF was inferred to be constant within 10% during Latitude Figure 38. Dependence of the atmospheric 10 Be production rate on the depth and the latitude as- suming the present magnetic field intensity and a solar activity of F = 700 MeV. ...
Context 12
... of cosmogenic nuclides observed in various archives on the Earth's surface are determined by their production, atmospheric mixing, and deposition processes. We concentrate here only on the production processes, which depend on both the latitude and the altitude (Figure 38). ...
Context 13
... a radiative balance of 235 W m −2 the Earth would have an average surface temperature of only −19 • C, resulting in a perpetually frozen planet (Ruddiman, 2001). Moreover, the standard solar model (Gough, 1981) predicts that the luminosity of the Sun 4.6 billion years (Ga) ago was only ≈70% of the present value and increased ever since due to the advancing conversion of hydrogen to helium in its core (Figure 48), making the early planet even more inhospitable to life. Yet the geologic record tells us that the planet had running water from at least 3.8 Ga ago (Windley, 1984) and abundant life since at least 3.5 Ga ago (Schopf, 1983). ...
Context 14
... the validity of the standard solar model, the Earth -even with the contri- bution from the greenhouse -should have been a frozen body until about 1 Ga ago ( Figure 48). Yet, the sedimentary record (Windley, 1984) demonstrates convinc- ingly the existence of open water bodies and streams, hence at least benign climate, during the entire Precambrian. ...
Context 15
... amplification by GCR-flux exists, whatever the actual pathway, it has to be modulated by the magnetosphere. The convincing correlations (Le Mouël et al., 2005;Veretenenko et al., 2005) of decadally smoothed TSI, temperature, "magnetic indices" (Figure 58), cyclonic activity and 10 Be clearly support the existence of such an amplifier. In view of these data, the potential discrepancy of the last 2-3 decades may require re-examination. ...
Context 16
... cautionary note is supported further by complementary observational data. In contrast to GCM's that hold the Earth's albedo roughly constant (≈0.3), the observational data by several approaches and groups (Pallé et al., 2005;Wild et al., 2005) show a significant Figure 58. Normalised time evolution of the 11-year running mean for magnetic indices (SIT) at Sitka, normalized solar irradiance (St) and global temperature (Tglobe) during the last century. ...

Similar publications

Data
Full-text available
The problem of the knee in primary cosmic ray at energy about 3–5 PeV is the most exciting problem in cosmic ray physics. Since 1958, physicists have been trying to solve this problem. In our opinion, the problem could be solved from the experimental point of view, whereas the primary spectrum would follow a pure power law. A key to the "knee" prob...
Article
Full-text available
The problem of the knee in primary cosmic ray at energy about 3-5 PeV is the most exiting problem in cosmic ray p h ysics. Since 1958 physicists try to solve this problem. On my opinion, the problem could be solved from the experimental point of view, whereas the primary spectrum would follow a pure power law. A key to the knee" problem lies in the...
Article
Full-text available
More than 100 years after their discoveries, cosmic rays have been extensively studied, both with balloon experiments and with ground observatories. More recently, the possibility of mounting detectors on satellites or on the International Space Station has allowed for a long duration (several years) continuous observation of primary cosmic rays, i...
Article
Full-text available
We use atmospheric neutrino data and MINOS data to constrain the MaVaN (Mass Varying Neutrinos) mechanism. The MaVaN model was largely studied in cosmology scenarios and comes from the coupling of the neutrinos with a neutral scalar depending on the local matter density. For atmospheric neutrinos, this new interaction affects the neutrino propagati...

Citations

... Specifically, the atmospheric ionization may alter the physical and chemical properties of the atmosphere and affect several processes, such as aerosol and cloud formation, atmospheric transparency, cloud cover, cyclogenesis and precipitation, especially in regions of middle and high geographic latitudes. Therefore, several numerical models were created and validated via comparison with direct observations and measurements of the CRII, e.g., the Sofia model [8,9], the Bern model, also called ATMOCOSMIC [10,11] and the Oulu model, also called CRAC:CRII [12,13]. Results from the latter model [14] are used in this work. ...
Article
Full-text available
The main source of the ionization of the Earth’s atmosphere is the cosmic radiation that depends on solar activity as well as geomagnetic activity. Galactic cosmic rays constitute a permanent radiation background and contribute significantly to the radiation exposure inside the atmosphere. In this work, the cosmic-ray-induced ionization of the Earth’s atmosphere, due to both solar and galactic cosmic radiation during the recent solar cycles 23 (1996–2008) and 24 (2008–2019), was studied globally. Estimations of the ionization were based on the CRAC:CRII model by the University of Oulu. The use of this model allowed for extensive calculations from the Earth’s surface (atmospheric depth 1033 g/cm2) to the upper limit of the atmosphere (atmospheric depth 0 g/cm2). Monte Carlo simulations were performed for the estimation quantities of radiobiological interest with the validated software DYASTIMA/DYASTIMA-R. This study was focused on specific altitudes of interest, such as the common flight levels used by commercial aviation.
... Consequently, the magnetic field that should be used in the calculations is not the Earth's internal magnetic field but a modified version of it, usually called the external geomagnetic field or magnetospheric field. For more details on magnetospheric and atmospheric effects see, e.g., Scherer et al. (2006). ...
Article
Full-text available
Simulating the irradiation of planetary atmospheres by cosmic ray particles requires, among others, the ability to understand and to quantify the interactions of charged particles with planetary magnetic fields. Here we present a process that is very often ignored in such studies: the dispersion and focusing of cosmic ray trajectories in magnetospheres. The calculations were performed using our new code CosmicTransmutation, which has been developed to study cosmogenic nuclide production in meteoroids and planetary atmospheres and which includes the computation of the irradiation spectrum on top of the atmosphere. Here we discuss effects caused by dispersion and focusing of cosmic ray particle trajectories.
... When a CME strikes Earth, this causes a worldwide temporary disturbance of Earth's magnetic field. The battle between charged particles and magnetic fields shake the Earth's magnetic field over a period of several hours or days (Scherer et al., 2006;Marusek, 2007). ...
Article
Full-text available
Evolutionarily, a human organism is adapted to the natural geomagnetic environment and its slight alterations. However, during geomagnetic storms (GMSs), the strength of the geomagnetic field (GMF) sharply increased hundreds of times and can pose a serious threat to people. We examine the effects of controlled compensation in the time-varying components of the GMF, using a specially created experimental setup with electrically shielding solutions, providing an electromagnetically quiet environment. The measurement of heart rate variability (HRV) on 25 healthy young male volunteers was carried out in the laboratory using the experimental setup at different levels of outdoor geomagnetic activity (GMA). The geomagnetic K-index was used to characterize the magnitude of GMSs; volunteers were tested during quiet magnetic days (K=1-3), days with K=4, and days with GMSs (K≥5) in the period of solar cycle maximum. During quiet magnetic days, the comparison between HRV baseline values with values measured under GMF time-varying components compensation mode (CM) did not reveal any changes. On days with K=4 some HRV indices shifted from their initial values, but it was statistically not significant. However, on days with GMSs statistically significant changes in SDNN* (p=0.033) and LF* (p=0.011) indices of HRV were observed in the GMS CM compared to their baseline values. The experiments showed that GMSs cause a sensitive reaction of the heart rate regulatory mechanism, the effect of which can be canceled in the GMS CM. The efficiency of the used technology is supported by the results of this study. * SDNN (Standard Deviation Normal to Normal R-R of cardiointervals), LF (Low frequency spectral band of cardiointervals).
... Consequently, the magnetic field that should be used in the calculations is not the Earth's internal magnetic field but a modified version of it, usually called external geomagnetic field or magnetospheric field. For more details on magnetospheric and atmospheric effects see, e.g., [12]. ...
Preprint
Simulating the irradiation of planetary atmospheres by cosmic ray particles requires, among others, the ability to understand and to quantify the interactions of charged particles with planetary magnetic fields. Here we present a process that is very often ignored in such studies; the dispersion and focusing of cosmic ray trajectories in magnetospheres. The calculations were performed using our new code CosmicTransmutation, which has been developed to study cosmogenic nuclide production in meteoroids and planetary atmospheres and which includes the computation of the irradiation spectrum on top of the atmosphere. Here we discuss effects caused by dispersion and focusing of cosmic ray particle trajectories.
... Several galactic processes affect the GCR flux in the inner Solar System, operating on a range of timescales [52][53][54]. On the longest timescales (>1 Gyr), the average GCR flux may reflect the galactic star formation rate, which could provide useful constraints on models of galactic evolution (although it would be necessary to account for an expected secular increase in GCR flux reaching the inner Solar System due to decreasing solar activity [11]). ...
Article
Full-text available
The lunar surface has been exposed to the space environment for billions of years and during this time has accumulated records of a wide range of astrophysical phenomena. These include solar wind particles and the cosmogenic products of solar particle events which preserve a record of the past evolution of the Sun, and cosmogenic nuclides produced by high-energy galactic cosmic rays which potentially record the galactic environment of the Solar System through time. The lunar surface may also have accreted material from the local interstellar medium, including supernova ejecta and material from interstellar clouds encountered by the Solar System in the past. Owing to the Moon's relatively low level of geological activity, absence of an atmosphere, and, for much of its history, lack of a magnetic field, the lunar surface is ideally suited to collect these astronomical records. Moreover, the Moon exhibits geological processes able to bury and thus both preserve and ‘time-stamp' these records, although gaining access to them is likely to require a significant scientific infrastructure on the lunar surface. This article is part of a discussion meeting issue ‘Astronomy from the Moon: the next decades'.
... Several galactic processes affect the GCR flux in the inner Solar System, operating on a range of timescales [52][53][54]. On the longest timescales (>1 Gyr), the average GCR flux may reflect the galactic star formation rate, which could provide useful constraints on models of galactic evolution (although it would be necessary to account for an expected secular increase in GCR flux reaching the inner Solar System due to decreasing solar activity [11]). ...
Preprint
Full-text available
The lunar surface has been exposed to the space environment for billions of years and during this time has accumulated records of a wide range of astrophysical phenomena. These include solar wind particles and the cosmogenic products of solar particle events which preserve a record of the past evolution of the Sun, and cosmogenic nuclides produced by high-energy galactic cosmic rays which potentially record the galactic environment of the Solar System through time. The lunar surface may also have accreted material from the local interstellar medium, including supernova ejecta and material from interstellar clouds encountered by the Solar System in the past. Owing to the Moon's relatively low level of geological activity, absence of an atmosphere, and, for much of its history, lack of a magnetic field, the lunar surface is ideally suited to collect these astronomical records. Moreover, the Moon exhibits geological processes able to bury and thus both preserve and 'time-stamp' these records, although gaining access to them is likely to require a significant scientific infrastructure on the lunar surface.
... In addition to providing information about the history of the Sun, noble gases have the potential to provide insight into the history of the Galaxy and its implications for the development of life on Earth. The Solar System has been subject to a wide range of galactic environments as it orbits the Galaxy, and the GCR flux is sensitive to a variety of astrophysical processes including the star formation rate and nearby supernova explosions (e.g., Scherer et al., 2006;Shaviv, 2006). As the Moon possesses some of the most ancient surfaces in the Solar System, it may preserve a record of enhanced galactic cosmic ray fluxes in cosmogenic noble gas isotopes, which could potentially provide information on the structure and evolution of the Galaxy (e.g. ...
Article
The lunar regolith provides a temporal archive of the evolution of the Moon and inner Solar System over the last ∼4 billion years. During this time, noble gases have been trapped and produced within soils and rocks at the lunar surface. These noble gas concentrations can be used to unravel the history of lunar material and shed light on processes that have evolved the surface of the Moon through time. We have collected published noble gas data for a range of lunar samples including soils, regolith breccias, crystalline (e.g., mare basalts, anorthosite) and impact-melt rocks. The compilation includes noble gas concentrations and isotope ratios for He, Ne, Ar, Kr and Xe; trapped, cosmogenic and radiogenic isotopes; and cosmic ray exposure ages. We summarise the significance of these data, which can be used as a baseline for expected noble gas concentrations in a range of lunar samples, and provide a framework for future in situ noble gas measurements on the lunar surface.
... The data, however, indicate differently; there is a large spread of data over the entire x-axis, indicating that there is no apparent periodicity. We found the same result for periods of 147 Ma (Scherer et al. 2006) and for 400 and 500 Ma (Alexeev 2016). Consequently, from our data, there is no indication for a periodicity in the CRE age data, which is in clear contradiction to the proposals by Shaviv (2002Shaviv ( , 2003, Scherer et al. (2006), andAlexeev (2016). ...
... We found the same result for periods of 147 Ma (Scherer et al. 2006) and for 400 and 500 Ma (Alexeev 2016). Consequently, from our data, there is no indication for a periodicity in the CRE age data, which is in clear contradiction to the proposals by Shaviv (2002Shaviv ( , 2003, Scherer et al. (2006), andAlexeev (2016). Furthermore, our result nicely confirms the earlier findings by Rahmstorf et al. (2004) and Jahnke (2005). ...
Article
Full-text available
We measured the He, Ne, and Ar isotopic concentrations and the 10Be, 26Al, 36Cl, and 41Ca concentrations in 56 iron meteorites of groups IIIAB, IIAB, IVA, IC, IIA, IIB, and one ungrouped. From 41Ca and 36Cl data, we calculated terrestrial ages indistinguishable from zero for six samples, indicating recent falls, up to 562 ± 86 ka. Three of the studied meteorites are falls. The data for the other 47 irons confirm that terrestrial ages for iron meteorites can be as long as a few hundred thousand years even in relatively humid conditions. The 36Cl‐36Ar cosmic ray exposure (CRE) ages range from 4.3 ± 0.4 Ma to 652 ± 99 Ma. By including literature data, we established a consistent and reliable CRE age database for 67 iron meteorites. The high quality of the CRE ages enables us to study structures in the CRE age histogram more reliably. At first sight, the CRE age histogram shows peaks at about 400 and 630 Ma. After correction for pairing, the updated CRE age histogram comprises 41 individual samples and shows no indications of temporal periodicity, especially not if one considers each iron meteorite group separately. Our study contradicts the hypothesis of periodic GCR intensity variations (Shaviv 2002, 2003), confirming other studies indicating that there are no periodic structures in the CRE age histogram (e.g., Rahmstorf et al. 2004; Jahnke 2005). The data contradict the hypothesis that periodic GCR intensity variations might have triggered periodic Earth climate changes. The 36Cl‐36Ar CRE ages are on average 40% lower than the 41K‐K CRE ages (e.g., Voshage 1967). This offset can either be due to an offset in the 41K‐K dating system or due to a significantly lower GCR intensity in the time interval 195–656 Ma compared to the recent past. A 40% lower GCR intensity, however, would have increased the Earth temperature by up to 2 °C, which seems unrealistic and leaves an ill‐defined 41K‐K CRE age system the most likely explanation. Finally, we present new 26Al/21Ne and 10Be/21Ne production rate ratios of 0.32 ± 0.01 and 0.44 ± 0.03, respectively.
... As discussed above, the Sun is traveling through the shell of the Loop I superbubble that resulted from stellar evolution in the ScoCen OB2 association. It was recognized long ago that extreme variations in the physical properties of interstellar material interacting with the solar system would probably affect the terrestrial climate [1,205,206,207,208,209,3]. These effects are mediated by the interaction between the heliosphere and interstellar medium [210,207,3,208,211,212]. ...
... It was recognized long ago that extreme variations in the physical properties of interstellar material interacting with the solar system would probably affect the terrestrial climate [1,205,206,207,208,209,3]. These effects are mediated by the interaction between the heliosphere and interstellar medium [210,207,3,208,211,212]. The 18 km s −1 motion of the solar system through the LSR and the 7-47 km s −1 LSR velocities of nearby interstellar clouds [121] lead to variations in the heliospheric boundary conditions over geological timescales of order ≤ 30 kyr [213]. ...
Article
A range of astronomical data indicates that ancient supernovae created the galactic environment of the Sun and sculpted the physical properties of the interstellar medium near the heliosphere. In this paper we review the characteristics of the local interstellar medium that have been affected by supernovae. The kinematics, magnetic field, elemental abundances, and configuration of the nearest interstellar material support the view that the Sun is at the edge of the Loop I superbubble, which has merged into the low density Local Bubble. The energy source for the higher temperature X-ray emitting plasma pervading the Local Bubble is uncertain. Winds from massive stars and nearby supernovae, perhaps from the Sco-Cen Association, may have contributed radioisotopes found in the geologic record and galactic cosmic ray population. Nested supernova shells in the Orion and Sco-Cen regions suggest spatially distinct sites of episodic star formation. The heliosphere properties vary with the pressure of the surrounding interstellar cloud. A nearby supernova would modify this pressure equilibrium and thereby severely disrupt the heliosphere as well as the local interstellar medium.
... The analysis of the distribution of this set led to contradictory conclusions regarding the variations of the GCR intensity. For example, Shaviv (2002;2003) concluded that this distribution of ages is the evidence for variations of the GCR intensity with the period of 143 ± 10 Myr (or, according to more recent data (Scherer et al., 2006), with the period of 143 ± 6 Myr), which are caused by presumed periodic passages of the Solar System through the spiral arms of the Galaxy. However, the very fact of variations with such a period, as well as the authors' conclusion about the supposed correlation between periodic changes in the GCR intensity and climatic changes on the Earth, are disputed by many researchers, as both the procedure of sampling the ages for analysis and the interpretation of the data are considered poorly grounded (Rahmstorf et al., 2004;Jahnke, 2005;Bailer-Jones, 2009;Overholt et al., 2009;Wieler et al., 2013). ...
Article
Full-text available
Based on the analysis of published data on exposure ages of iron meteorites determined with the ⁴⁰K/K method (TK) and ages calculated using short-lived cosmogenic radionuclides (with the half-life T1/2 < 1 Myr) in combination with stable cosmogenic isotopes of noble gases (TRS), the following results have been obtained. (1) The distribution of TRS ages (106 values) has an exponential shape, similar to that for ordinary chondrites, but different from the distribution of TK ages (80 values). The difference is most likely due to small amounts of data for meteorites with low TK ages (less than ~200–300 Myr). The latter can be ascribed to the difficulty of measurement of small concentrations of cosmogenic potassium isotopes. This circumstance makes the selection of meteorites with ⁴⁰K/K ages nonrepresentative and casts doubt on the correctness of conclusions about the variations of the intensity of galactic cosmic rays (GCR) based on the analysis of distribution of these ages. (2) The magnitude of the known effect (systematic overestimation of TK ages in comparison with TRS ages) has been refined. The value k = TK/TRS = 1.51 ± 0.03 is acquired for the whole population of data. We have shown the inefficiency of the explanation of this effect on account of an exponential change in the GCR intensity (IT) with time (T) according to the relation IT = I0exp(–γT) over the whole range of ages of iron meteorites. (3) In order to explain the overestimation of TK ages in comparison with TRS ages, a model has been proposed, according to which the GCR intensity has exponentially increased in the interval of 0–1500 Myr governed by the relation: IT = IT = 1500 (1 + αexp(–βT)). For one of the variants of this model, the GCR intensity has exponentially increased by a factor of two only over the recent ~300 Myr, remaining approximately constant for the rest of the time. The data acquired with the use of this model indicate that the measured TK ages are close to the actual time that the meteorites existed in space; the data are in agreement with the observed exponential distribution of TRS ages.