共查询到20条相似文献，搜索用时 529 毫秒
1.
The data from terrestrial observations of cosmic rays at the global network of stations by the method of spectrographic global survey were used to analyze two Forbush decreases during the geomagnetic storms in March and June 2015. The spectra of cosmic ray variations, pitch angle anisotropy of cosmic rays at different phases of Forbush decrease development, and the changes in the planetary system of geomagnetic cutoff rigidities are presented. It is shown that, during the approximation of the spectra of variations by the power function of particle rigidity in the interval of 10–50 GV, the spectrum index is softer at the maximum modulation phase than during the phases of cosmic ray intensity decline and recovery. In the axisymmetric model of the bounded magnetosphere of the Earth, which takes into account the currents at the magnetopause and the ring current, the distance to the subsolar point and the radius of the ring current, as well as the contribution of the ring current to the changes in geomagnetic cutoff rigidity and to the Dst index during the studied events, are determined. 相似文献
2.
A. V. Belov B. D. Shelting R. T. Gushchina V. N. Obridko A. F. Kharshiladze V. G. Yanke 《Journal of Atmospheric and Solar》2001,63(18)
The paper deals with the relation of long-term variations of 10 GV galactic cosmic rays (GCR) to the global solar magnetic field and solar wind parameters. This study continues previous works, where the tilt of the heliospheric current sheet (HCS) and other solar-heliospheric parameters are successfully used to describe long-term variations of cosmic rays in the past two solar cycles. The novelty of the present work is the use of the HCS tilt and other parameters reconstructed from Hα observations of filaments for the period when direct global solar magnetic field observations were unavailable. Thus, we could extend the GCR simulation interval back to 1953. The analysis of data for 1953–1999 revealed a good correlation (the correlation coefficient >0.88) between the solar-heliospheric parameters and GCR in different cycles of solar activity. Moreover, the approach applied makes it possible to describe the behavior of cosmic rays in the epochs of solar maxima, which could not be done before. This indicates both the adequacy of the model and the reliability of the reconstructed global solar magnetic field parameters. 相似文献
3.
4.
Geomagnetism and Aeronomy - The correlation of the variations in geomagnetic cutoff rigidity of cosmic rays ΔR with the interplanetary medium parameters and geomagnetic activity indices Dst... 相似文献
5.
An analytical expression is derived for the cutoff rigidity of cosmic rays arriving at a point in an arbitrary direction, when the main geomagnetic field is approximated by that of an eccentric dipole. This expression is used to determine changes in geomagnetic cutoffs due to secular variation of the geomagnetic field since 1835. Effects of westward drift of the quadrupole field and decrease in the effective dipole moment are seen in the isorigidity contours. On account of the immense computer time required to determine the cutoff rigidities more accurately using the particle trajectory tracing technique, the present formulation may be useful in estimating the transmission factor of the geomagnetic field in cosmic ray studies, modulation of cosmogenic isotope production by geomagnetic secular variation, and the contribution of geomagnetic field variation to long term changes in climate through cosmic ray related modulation of the current flow in the global electric circuit. 相似文献
6.
Ptitsyna N. G. Danilova O. A. Tyasto M. I. Sdobnov V. E. 《Geomagnetism and Aeronomy》2021,61(2):169-179
Geomagnetism and Aeronomy - The correlations between variations in the geomagnetic cutoff rigidity of cosmic rays and the Dst and Kp geomagnetic indices and solar-wind and IMF parameters are... 相似文献
7.
8.
《Journal of Atmospheric and Solar》2008,70(7):1122-1131
Galactic cosmic rays (GCR) have been suggested as a possible contributory mechanism to cloud formation. If these are significant then, in addition to the similarity between long-term (years) changes in GCR and cloud cover, there should also be a similarity over shorter (days) time scales. This paper reports an analysis of changes in global cloud cover and GCR recorded at 3 hourly intervals over 22 years. There is a significant correlation between short-term changes in low cloud cover over northern and southern hemispheres, consistent with about 3% of the variation arising from common factors. However, GCR is not a major factor responsible for cloud cover changes. There is an association between short-term changes in low cloud cover and galactic cosmic radiation over a period of several days. This could arise if approximately 3% of the variations in cloud cover resulted from GCR. 相似文献
9.
The variations in the rigidity spectrum and anisotropy of cosmic rays in December 2006 have been studied based on the surface measurements of the cosmic ray intensity at the global network of stations, using the method of global spectrographic survey. It has been indicated that the highest degree of anisotropy (to ～50%) with the maximal intensity of particles with a rigidity of 4 GV in the direction from the Sun (an asymptotic direction of about ?25° and 160°) was observed at 0400 UT on December 13. The parameters of the cosmic ray rigidity spectrum, which reflect the electromagnetic characteristics of the heliospheric fields during the studied period, have been determined when the surface and satellite measurements of protons in the energy range from several megaelectronvolts to several tens of gigaelectronvolts were jointly analyzed. The observed anisotropy and variations in cosmic rays in a wide energy range have been explained based on an analysis of the results. 相似文献
10.
V. K. Korotkov 《Geomagnetism and Aeronomy》2007,47(1):37-42
Based on the multiplied neutron registration with the Magadan neutron monitor, the parameters of the spectrum of variations in the cosmic ray hardness and variation in geomagnetic cutoff rigidity for Forbush decreases and intensity increases, related to registration at a level of solar cosmic ray observation, have been determined using the spectrographic method. Results of an analysis indicate that the spectral index (represented in the power form) increases for Forbush decreases and decreases for increases in CR intensity. In the analyzed cases, geomagnetic cutoff rigidity decreases for intensity increases and Forbush decreases. 相似文献
11.
V. A. Dergachev P. B. Dmitriev O. M. Raspopov H. Jungner 《Geomagnetism and Aeronomy》2006,46(1):118-128
Direct and indirect data on variations in cosmic rays, solar activity, geomagnetic dipole moment, and climate from the present to 10–12ka ago (the Holocene Epoch), registered in different natural archives (tree rings, ice layers, etc.), have been analyzed. The concentration of cosmogenic isotopes, generated in the Earth’s atmosphere under the action of cosmic ray fluxes and coming into the Earth archives, makes it possible to obtain valuable information about variations in a number of natural processes. The cosmogenic isotopes 14C in tree rings and 10Be in ice layers, as well as cosmic rays, are modulated by solar activity and geomagnetic field variations, and time variations in these concentrations gives information about past solar and geomagnetic activities. Since the characteristics of natural reservoirs with cosmogenic 14C and 10Be vary with climate changes, the concentrations of these isotopes also inform about climate changes in the past. A performed analysis indicates that cosmic ray flux variations are apparently the most effective natural factor of climate changes on a large time scale. 相似文献
12.
The cosmic ray geomagnetic cutoff rigidities are obtained by analytical calculations within an axisymmetric model of bounded magnetosphere, the magnetic field of which is created by the dipole field of the Earth and by two spheres located beyond the Earth with the currents that flow along the parallels and have a value proportional to the cosine of latitude. The inner sphere models the ring current flowing in the westerly direction; the outer sphere simulates the currents over the magnetopause, which flow in the easterly direction. The analytical results of calculations of variations in the geomagnetic cutoff rigidity for different levels of geomagnetic disturbances are given. The results are compared with the results of analytical calculations within the model of unbounded magnetosphere (when the outer sphere is absent). 相似文献
13.
14.
Geomagnetism and Aeronomy - Stellar and galactic cosmic rays (SCR and GCR) are the primary factors influencing the radiation conditions near exoplanets. The GCR spectrum and its time variations are... 相似文献
15.
The variations in the geomagnetic cutoff rigidity in Irkutsk, Alma-Ata, and Beijing in October–November 2003 were calculated
using ground-based measurements of cosmic ray intensity from the worldwide network of stations and GOES spacecraft. The calculated
variations in geomagnetic cutoff rigidity are presented together with D
st variations of the geomagnetic field. The obtained results are compared to calculations performed using the Tsyganenko model
of the magnetosphere. 相似文献
16.
Variations in the cosmic ray intensity (specifically, Forbush effects) and in the geomagnetic cutoff rigidity planetary system during powerful geomagnetic disturbances in cycle 23 were studied based on worldwide station network data by the global spectrographic survey method. The cosmic ray variation spectra during these periods and the spectral indices of these variations when the spectrum was approximated by the power function of the particle rigidity varying from 10 to 50 GV during different Forbush effect development phases are presented. It was indicated that the spectral indices of cosmic ray variations during spectrum approximation by the power function of the particle rigidity are larger during the maximal modulation phase than during the cosmic ray intensity decline and recovery phases. The fact that the amplitude of the second harmonic of the cosmic ray pitch angle anisotropy did not increase on November 20, 2003, confirms that the Earth fell into a Sun-independent spheromark magnetic cloud. The increased amplitudes of the second harmonic of the cosmic ray pitch angle anisotropy during other Forbush effects in July 2000, March–April 2001, October 2003, and November 2004 indicate that the Earth was in the coronal mass ejection region, in which the interplanetary magnetic field structure was loop-like during these periods. 相似文献
17.
Jasper Kirkby 《Surveys in Geophysics》2007,28(5-6):333-375
Among the most puzzling questions in climate change is that of solar-climate variability, which has attracted the attention of scientists for more than two centuries. Until recently, even the existence of solar-climate variability has been controversial—perhaps because the observations had largely involved correlations between climate and the sunspot cycle that had persisted for only a few decades. Over the last few years, however, diverse reconstructions of past climate change have revealed clear associations with cosmic ray variations recorded in cosmogenic isotope archives, providing persuasive evidence for solar or cosmic ray forcing of the climate. However, despite the increasing evidence of its importance, solar-climate variability is likely to remain controversial until a physical mechanism is established. Although this remains a mystery, observations suggest that cloud cover may be influenced by cosmic rays, which are modulated by the solar wind and, on longer time scales, by the geomagnetic field and by the galactic environment of Earth. Two different classes of microphysical mechanisms have been proposed to connect cosmic rays with clouds: firstly, an influence of cosmic rays on the production of cloud condensation nuclei and, secondly, an influence of cosmic rays on the global electrical circuit in the atmosphere and, in turn, on ice nucleation and other cloud microphysical processes. Considerable progress on understanding ion–aerosol–cloud processes has been made in recent years, and the results are suggestive of a physically-plausible link between cosmic rays, clouds and climate. However, a concerted effort is now required to carry out definitive laboratory measurements of the fundamental physical and chemical processes involved, and to evaluate their climatic significance with dedicated field observations and modelling studies. 相似文献
18.
The production rate profiles of21Ne and22Ne as a function of depth in meteoroids due to spallation by solar flare cosmic rays (SCR) and galactic cosmic rays (GCR) are calculated and their dependence on size and composition of meteoroids has been evaluated. The GCR production rate at a given depth increases with size for radii<25cm and then decreases whereas the22Ne21Ne ratio (NeR) generally decreases with size and depth. The calculated GCR production rates and NeR are consistent with the measurements in several Chondrites. A plot of track production rate vs. NeR shows that some chondrites have NeR values smaller than those expected for their sizes. Thes obeervation suggestsat least a two-stage irradiation for such meteorites; the meteoroid exposure as a small body in the interplanetary space must have been preceded by exposure under deep shielding, possibly in its parent body. 相似文献
19.
During the prolonged and deep minimum of solar activity between cycles 23 and 24, an unusual behavior of the heliospheric characteristics and increased intensity of galactic cosmic rays (GCRs) near the Earth’s orbit were observed. The maximum of the current solar cycle 24 is lower than the previous one, and the decline in solar and, therefore, heliospheric activity is expected to continue in the next cycle. In these conditions, it is important for an understanding of the process of GCR modulation in the heliosphere, as well as for applied purposes (evaluation of the radiation safety of planned space flights, etc.), to estimate quantitatively the possible GCR characteristics near the Earth in the upcoming solar minimum (~2019–2020). Our estimation is based on the prediction of the heliospheric characteristics that are important for cosmic ray modulation, as well as on numeric calculations of GCR intensity. Additionally, we consider the distribution of the intensity and other GCR characteristics in the heliosphere and discuss the intercycle variations in the GCR characteristics that are integral for the whole heliosphere (total energy, mean energy, and charge). 相似文献
20.
A. V. Belov E. A. Eroshenko V. G. Yanke V. A. Oleneva M. A. Abunina A. A. Abunin 《Geomagnetism and Aeronomy》2018,58(3):356-372
One of the variants of the global survey method developed and used for many years at the Institute of Terrestrial Magnetism, Ionosphere, and Radio Wave Propagation of the Russian Academy of Sciences is described. Data from the world network of neutron monitors for every hour from July 1957 to the present has been processed by this method. A consistent continuous series of hourly characteristics of variation of the density and vector anisotropy of cosmic rays with a rigidity of 10 GV is obtained. A database of Forbush decreases in galactic cosmic rays caused by large-scale disturbances of the interplanetary medium for more than half a century has been created based on this series. The capabilities of the database make it possible to perform a correlation analysis of various parameters of the space environment (characteristics of the Sun, solar wind, and interplanetary magnetic field) with the parameters of cosmic rays and to study their interrelationships in the solar–terrestrial space. The features of reception coefficients for different stations are considered, which allows the transition from variations according to ground measurements to variations of primary cosmic rays. The advantages and disadvantages of this variant of the global survey method and the opportunities for its development and improvement are assessed. The developed method makes it possible to minimize the problems of the network of neutron monitors and to make significant use of its advantages. 相似文献