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1.
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
2.
This paper addresses observed variations in cosmic ray (CR) intensity, the interplanetary magnetic field (IMF), the solar
wind (SW) turbulence energy spectrum, and the energy spectrum index of Forbush decreases in the 20th–23rd solar cycles. Unlike
the previous three cycles, there are some distinctive features in the 23rd solar cycle. The entire cycle shows a considerable
increase in the index of the SW turbulence energy spectrum inclination and an substantially harder energy spectrum of Forbush
decreases. The anomalously high flux of high-energy CRs and the anomalously low level of the IMF strength were recorded at
the end of this cycle. The conclusion has been made that such unusual CR behavior is associated with a decrease in the degree
of scattering in the resonance interaction between CR fluxes and SW inhomogeneities with spatial scales of ∼1012 cm. 相似文献
3.
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
4.
Cosmic ray (CR) fluxes, which penetrate into the Earth??s magnetosphere and atmosphere from the interplanetary space, are an important factor of space weather. The geomagnetic field allows or forbids CR particles to enter into a given point in the magnetosphere depending on their energy. The geomagnetic cutoff rigidity regulates the distribution of CR fluxes in the magnetosphere. The geomagnetic cutoff rigidity (geomagnetic threshold) determination accuracy is closely related to the accuracy of the magnetospheric model used in calculations. Using a method for tracing of charged CR particle trajectories in the magnetic field of a model magnetosphere, we obtained geomagnetic thresholds for two magnetosphere empirical models (Ts01 and Ts04), constructed based on the same initial database. The Ts01 model describes the middle magnetosphere for certain conditions in the solar wind and interplanetary field. The Ts04 model pays the main attention to describing the large-scale evolution of magnetospheric currents during a storm. The theoretically obtained geomagnetic thresholds have been compared with experimental thresholds, calculated using the spectrographic global survey method based on data from the global network of CR stations. The study has been performed for the period of a strong geomagnetic storm that occurred in November 2003. 相似文献
5.
We analyze variations in the rigidity spectrum of primary cosmic rays during Forbush effects recorded in cycles 20–24 of solar activity on the basis of data from the global network of neutron monitor stations processed by global survey. We investigate variations in the rigidity spectrum index of Forbush effects as a function of the solar activity level, phases of the effect, polarity the total magnetic field of the Sun, type and parameters of the source of cosmic ray modulation, etc. Comprehensive analysis of our results revealed regularities in the dynamics of the energy spectrum of galactic cosmic rays that reflect the dynamic processes occurring in the interplanetary space. 相似文献
6.
《Journal of Atmospheric and Solar》2005,67(10):907-912
We availed hourly data of four middle and high cut-off rigidity neutron monitors recorded over 21 years and then discussed various measures of the CR variability and simplified estimates of the CR anisotropy in relation to the Dst time history. The correlation of Dst with the prehistory of CR variability at these cut-offs is shown. A different distribution of the CR indices for 24 h before the sharp Dst decreases in comparison with that for geomagnetically quiet periods is found. The relation of CR variability with the solar wind speed appeared but neither with the solar wind density nor with the Bz component of the interplanetary magnetic field. The multiple regression of Dst with the prehistory of CR variability resulted to be significant, suggesting that the parameters describing CR variability/anisotropy are potentially useful to be implemented into the schemes of forecasting of geomagnetic activity, performed with interplanetary medium data obtained before their arrival at the Earth (e.g. at the L1 point). 相似文献
7.
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
8.
Using the spectrographic global survey method, variations in the rigidity spectrum and anisotropy of galactic cosmic rays
(March 1991) have been studied using data from ground-based observations of cosmic rays (CR) at the worldwide network of stations.
Variations in geomagnetic cutoff rigidity (GCR) have been calculated. The paper also presents latitudinal GCR variations at
certain moments of the considered period for different geomagnetic field disturbance levels. Calculation results of GCR variations
have been compared with those of effect of the westward current flowing with a strength proportional to the latitude cosine
along parallels on the sphere, for different radii of the current ring in the dipole field. 相似文献
9.
M. I. Tyasto O. A. Danilova V. M. Dvornikov V. E. Sdobnov 《Geomagnetism and Aeronomy》2008,48(6):691-708
The time variations in the CR geomagnetic cutoff rigidity and their relation to the interplanetary parameters and the Dst index during a strong magnetic storm of November 18–24, 2003, have been analyzed. The Tsyganenko (Ts03) model of a strongly disturbed magnetosphere [Tsyganenko, 2002a, 2002b; Tsyganenko et al., 2003] have been used to calculate effective geomagnetic thresholds with the help of the method for tracing CR particle trajectories in the magnetospheric magnetic field. The geomagnetic thresholds have been calculated using the method of global spectrographic survey (GSS), based on the data from the global network of CR stations, and the results have been compared with the effective geomagnetic cutoff rigidities. The daily anisotropy of effective geomagnetic thresholds during the Dst variation minimum have been estimated. The relation of the theoretical and experimental geomagnetic thresholds, obtained using the GSS method, to the interplanetary parameters and Dst variation is analyzed. The Dst variations, IMF B z , and solar wind density are most clearly defined in the geomagnetic thresholds during this storm. The correlation between B y and experimental geomagnetic thresholds is higher than such a correlation between this parameter and theoretical thresholds by a factor 2–3, which suggests that a real dawn-dusk asymmetry during this storm was stronger than such an asymmetry represented by the Ts03 model. 相似文献
10.
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
11.
《Journal of Atmospheric and Solar》2003,65(9):1021-1033
Analysis of the time series into trigonometric series allows the investigation of cosmic-ray (CR) intensity variations in a range of periodicities from a few days to 1 year. By this technique the amplitude and the phase of all observed fluctuations can be given. For this purpose, daily CR intensity values recorded at Climax Neutron Monitor station for the time intervals 1979–1982 and 1989–1991, which correspond to the epochs of maximum activity for solar cycles 21 and 22, respectively, have been studied. The data analysis revealed the occurrence of new periodicities, common or not, in the two solar maxima. A search of our results was done by a power spectral analysis determining independently possible systematic periodic or quasi-periodic variations. Based on the fact that during these maxima the CR intensity tracks the solar flare index better than the sunspot number, the same analysis was performed on these data, which are equivalent to the total energy emitted by the solar flares. Both analyses result in periodicities with different probability of occurrence in different epochs. Occurrence at peaks of 70, 56, 35, 27, 21 and 14- days were observed in all time series, while the periods of 140–154 and 105 days are reported only in the 21st solar maximum and are of particular importance. All of the short-term periods except of those at 27 and 154-days are recorded for first time in CR data, but they had already been observed in the solar activity parameters. Moreover, each parameter studied here has a very different power spectrum distribution in periods larger than 154 days. The possible origin of the observed variations in terms of the CR interaction in the upper atmosphere and the solar cavity dynamics is also discussed here. 相似文献
12.
A. V. Belov M. A. Abunina A. A. Abunin E. A. Eroshenko V. A. Oleneva V. G. Yanke 《Geomagnetism and Aeronomy》2017,57(4):389-397
Variations in the cosmic-ray vector anisotropy observed on Earth are closely connected with the state of the near-Earth interplanetary medium. Hourly characteristics of vector anisotropy for the period 1957–2013, which were obtained by the global survey method from the data of the worldwide network of neutron monitors, make it possible to study the relationship between the cosmic-ray anisotropy and solar wind parameters. In the present work, we have studied the connection between the equatorial component of anisotropy of cosmic rays with a rigidity of 10 GV and the following parameters: velocity and density of the solar wind; density of the interplanetary magnetic field; and cosmic-ray density variations, in which the spatial gradient of cosmic rays in the interplanetary medium is manifested. The characteristics of cosmic-ray anisotropy at various combinations of the interplanetary medium parameters are compared. The possibility of diagnosing the solar wind state from data on the cosmic-ray anisotropy is discussed. 相似文献
13.
R. T. Gushchina A. V. Belov E. A. Eroshenko V. N. Obridko E. Paouris B. D. Shelting 《Geomagnetism and Aeronomy》2014,54(4):430-436
Recent years allowed us to study long-term variations in the cosmic ray (CR) intensity at an unusually deep solar activity (SA) minimum between cycles 23 and 24 and during the SA growth phase in cycle 24, which was the cycle when SA was the lowest for the epoch of regular ground-based CR observations since 1951. The intensity maximum, the value of which depends on the particle energy, was observed in CR variations during the period of an unusually prolonged SA minimum: the CR density during the aformentioned period (2009) is higher than this density at previous CR maxima in cycles 19–23 for low-energy particles (observed on spacecraft and in the stratosphere) and medium-energy particles (observed with neutron monitors). After 2009 CR modulation at the SA growth phase was much weaker over three years (2010–2012) than during the corresponding SA growth periods in the previous cycles. The possible causes of this anomaly in CR variations, which are related to the CR residual modulation value at a minimum between cycles 23 and 24 and to variations in SA characteristics during this period, were examined. The contribution of different solar magnetic field characteristics and indices, taking into account sporadic solar activity, has been estimated. 相似文献
14.
O. M. Chugunova V. A. Pilipenko S. L. Shalimov M. Engebretson 《Geomagnetism and Aeronomy》2008,48(3):307-313
The variations in the daily average energy of geomagnetic pulsations and noise in the Pc3 (20–60 mHz) and Pc4 (10–19 mHz) frequency bands in the polar cap have been studied based on the data from P5 Antarctic station (corrected geomagnetic latitude ?87°) from November 1998 to November 1999. The daily average pulsation energy has been calculated using the method for detecting the wave packets, the spectral amplitude of which is higher than the threshold level, from the dynamic spectrum. A spectral analysis of the energy of pulsations and noise in the Pc3 and Pc4 bands, performed using the maximal entropy method, has revealed periodicities of 18 days in the local winter and 26, 13, and 7–9 days during the local summer. The simultaneous and coherent variations with periods of 26, 13, and 7–9 days in the solar wind velocity and IMF orientation indicate that the variations in the Pc3–4 wave energy in the polar cap at a sunlit ionosphere are mainly controlled by the parameters of the interplanetary medium. The variations in the Pc3–4 wave energy with a period of 18 days are observed only during the local winter and are supposedly related to the variations in the ionospheric conductivity modulated by planetary waves. 相似文献
15.
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
16.
V. P. Antonova K. E. Dungenbaeva A. V. Zalizovskii A. S. Inchin S. V. Kryukov V. M. Somsikov Yu. M. Yampol’skii 《Geomagnetism and Aeronomy》2006,46(1):101-109
The singularities of the wave disturbance spectra of the nonequilibrium atmosphere in the range of acoustic gravity waves (AGWs) have been analyzed. Using the dispersion ratio for AGWs in the nonequilibrium atmosphere, it has been established that the spectra in the daytime and nighttime hours are different and this difference, caused by a nonequilibrium spectrum sensitivity to atmospheric temperature, can reach several percent in certain atmospheric regions. For the spectrum of the equilibrium model of the atmosphere, the difference between the daytime and nighttime spectra makes up several fractions of percent. As a result of the spectral treatment of variations in pressure and intensity of cosmic rays (CRs), it has been found out that the daytime AGW spectrum is higher-frequency than the nighttime spectrum. A comparison of the theoretical calculations of the AGW spectrum with observations has made it possible to distinguish the effect of nonequilibrium in the AGW spectral composition. 相似文献
17.
V. I. Vlasov 《Geomagnetism and Aeronomy》2013,53(2):137-146
Fluctuations in the intensity of cosmic radiosources, which are slower than interplanetary scintillations and are observed during radio astronomical studies of the solar wind, are discussed. It has been indicated that daytime variations (on average, from 8 to 16 h) are caused by large-scale disturbances in the solar wind rather than are of an ionospheric origin. A conclusion is made that such variations can be used to study the near-solar interplanetary space and predict space weather. 相似文献
18.
本文基于电磁波频谱理论研究方法,对2008年四川汶川MS8.0地震前后金河、剑阁及郑州二砂三个电磁波台站的观测资料进行FFT和小波变换分析,研究了电磁辐射数据快速傅里叶频谱变化特征和在不同尺度下小波变化的分解,发现在汶川地震前确实有异常信息存在.结果表明:(1) FFT动态谱图像说明,地震前电磁波频谱变化特征较明显,在时间、频段上均显示了阶段性进程特征,且随着震中距的增大,辐射能量越小,异常出现的时间越晚;(2) 小波分解显示了地震前电磁波异常信号低频部分出现的时间较早;距震中较近的台站,异常信息在高频部分相对明显;距震中稍远的台站,异常信息在低频部分相对明显. 相似文献
19.
We describe a method for monitoring geophysical (atmospheric and magnetospheric) parameters on the basis of cosmic rays (CR). The method is based on the principle of multichannel synchronous recording of all secondary components of CR in the energy range from a few to 200 GeV. The geophysical parameters are found from solving a system of equations for CR variations. The results of CR monitoring using a multichannel observation complex for the period from January, 2004 are considered. 相似文献
20.
A. A. Melkumyan A. V. Belov M. A. Abunina A. A. Abunin E. A. Eroshenko V. A. Oleneva V. G. Yanke 《Geomagnetism and Aeronomy》2018,58(5):615-624
The IZMIRAN database of Forbush effects and interplanetary disturbances has been used to study long-term changes in the number and magnitude of Forbush effects in the last six solar cycles (1957–2016) for cosmic rays of rigidity of 10 GV. Solar activity cycles have been shown to be well expressed in data of Forbush effects, especially in large magnitude events that almost disappear in minima. The changes in the distribution of Forbush effects and the decrease in their average values from solar activity maximum to minimum are explained by the predominance of cosmic-ray variations due to the action of coronal holes at low activity. It should be noted that the current cycle involves fewer and generally weaker Forbush effects than in the previous five cycles. For each month, an FD index combining the magnitude and number of Forbush effects and convenient for studying long-term variations has been proposed and calculated. 相似文献