Vector anisotropy of cosmic rays in the beginning of Forbush effects

We consider the behavior of anisotropy and density of galactic cosmic rays in the first hours of Forbush effects from 1957 to 2014 initiated by the arrival of a shock wave. It has been shown that, as early as the event commencement, the first harmonic of anisotropy tends to increase substantially and its direction changes significantly. The more is powerful the interplanetary disturbance, the greater are the changes. Based on changes in some parameters of anisotropy and density, we can estimate the heliolongitude of the disturbance source, as well as the further development of the Forbush effect and geomagnetic activity.     

根据VLF的相位变化确定D层宇宙线强度变化的可能性

银河宇宙线是电离层D层的重要电离源之一,它的急剧变化会使D层电子密度发生改变,从而影响VLF波的夜间传播。本文根据在西安接收英国GBR台的VLF波（16kc/s）的相位变化,讨论了在有宇宙线暴（Forbush下降）和强磁暴时,中纬D层电子浓度的变化和相应的VLF波的相位漂移;并根据VLF的相位变化,估计了相应的宇宙线强度变化。由于D层中的宇宙线强度变化通常难于观测,通过VLF波的相位漂移来估计它,这是很有意义的。所以,VLF波的传播效应可能成为间接探测宇宙线强度变化的有用工具。     

耀斑-激波的南-北非对称性传播

本文根据宇宙线Forbush下降幅度随源耀斑纬度分布的新近结果,采用无量纲化的MHD平面斜激波跃变条件,推算得到子午面内一种可能的耀斑-激波模型。发现耀斑-激波在太阳子午面内的传播相对耀斑法线方向是非对称的,激波面后的动力学参数与磁场具有截然相反的非对称性分布;激波传播的最快方向倾向日球电流片方向。该模型可以解释太阳耀斑-地磁、宇宙线效应中的南-北非对称性现象,有助于了解高速等离子体和非均匀背景场之间的相互作用过程。     

Effect of solar and galactic cosmic rays on the duration of macrosynoptic processes

The effect of solar and galactic cosmic ray variations on the duration of elementary synoptic processes (ESPs) in the Atlantic-European sector of the Northern Hemisphere has been studied. It has been found that solar cosmic ray (SCR) bursts result in an increase in the duration of ESPs, which belong to the western and meridional forms of atmospheric circulation. Forbush decreases in galactic cosmic rays (GCRs) are accompanied by an increase in the duration of ESPs, which belong to the meridional atmospheric circulation form, and in a decrease in the duration of ESPs, which are related to the western and eastern circulation forms. It has been assumed that the observed variations in the ESP duration are caused by the effect of short-period cosmic ray variations on the intensity of cyclonic processes at middle and high latitudes, namely, the regeneration of cyclones near the southeastern coast of Greenland after SCR bursts and the development of blocking anticyclones over the northeastern Atlantic, Europe, and Scandinavia during GCR Forbush decreases.     

Cosmic rays during great geomagnetic storms in cycle 23 of solar activity

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.     

Relationship between Forbush effect parameters and the heliolongitude of solar sources

All significant events in galactic cosmic rays for the last 55 years have been collected in a Forbush effect database created at the Pushkov Institute of Terrestrial Magnetism, Ionosphere, and Radiowave Propagation (hereinafter, IZMIRAN) based on data from the global network of neutron monitors. The solar sources of ～800 of these events have been identified. These events were divided into five groups with respect to the heliolongitudes of the associated X-ray solar flares, and typical behavior of their characteristics such as cosmic ray density and anisotropy, was studied independently for each group. The Forbush effect characteristics, which are the most dependent on the source heliolongitude, have been identified.     

Specific features of the rigidity spectrum of Forbush effects

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.     

The energy spectrum of Forbush decreases during the growth phase of solar cycle 24

The Forbush decrease energy spectrum, observed during the growth phase of cycle 24 in 2010–2012, was studied based on the measurements performed with the Kuzmin cosmic ray spectrograph. The data of the 24-NM-64 neutron monitor and muon telescopes, installed at water equivalent levels of 0, 7, 20, and 40 m, was used. The performed analysis indicated that a softer energy spectrum was observed during the growth phase of cycle 24 than during the previous cycle (cycle 23). The conclusion was been drawn that a more turbulent magnetic field with the predominant diffusion mechanism in the formation of the Forbush decreases in the cosmic ray intensity exists in the current cycle (cycle 24).     

Schumann resonance amplitude during the Forbush effect

The time variations in the galactic cosmic ray (GCR) intensity at Apatity stations have been compared to the amplitude of the first Schumann resonance (as an indicator of the global thunderstorm activity power) for 12 cases of Forbush decreases in GCRs. A performed analysis indicated that the amplitude of the first Schumann resonance decreased only once during a Forbush decrease in GCRs as compared to the quiet conditions (during the strongest event in January 2005). In the remaining cases, a statistically significant effect was not observed.     

Spectrographic analysis of events in cosmic rays in October–November 2003

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.     

Spatial-Energy Characteristics of Cosmic Rays and Parameters of Magnetospheric Current Systems in March and June 2015

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.     

根据宇宙线Forbush下降计算地球轨道附近的耀斑击波

本文根据Forbush下降幅度随源耀斑经度分布的东、西不对称性,得到了有关地球轨道附近的一种由耀斑引起的冲击波模型。发现冲击波各向异性传播且表现出东、西不对称性。击波西部是强磁场区,东部为弱磁场区。与此相反,动力学参数和等离子体参数β则是东部比西部高。耀斑产生的扰动有分别向东、西方向的方位角速度存在。该模型同观测资料和理论推论是一致的。它能对磁扰和宇宙线Forbush下降等东、西不对称效应给出统一而自然的解释。耀斑等离子体流的这种东、西不对称性流动的可能起因也作了讨论。     

Formation of a local atmospheric electric field

We have estimated the variations in the atmospheric electrostatic field (AEF, E _Z(0)) strength in the surface layer caused by variations in conductivity due to radon influences, cosmic ray intensity, changes in the balance of light and heavy ions during sunset and sunrise, and under the effect of the ionospheric electric current potential on the AEF potential. It is shown that the air conductivity varies due to ionization under the effect of radon emanations and is determined by the radon exhalation and turbulent diffusion of the surface air layer, while the cosmic ray intensity affects the surface air conductivity through changes in the ion recombination conditions. A decrease in the air conductivity due to a decrease in the cosmic ray intensity (Forbush decrease) also decreases E _Z(0), while a decrease in radon fluxes results in an increase in E _Z(0). We have estimated the effect of illumination conditions on the AEF due to variations in the relative concentration of heavy and light ions under the influence of photodetachment and photoattachment processes. The work has been done on the basis of data received from the Paratunka observatory (Kamchatka).     

宇宙线小波分析在大地磁暴预报中的应用

利用Morlet小波变换方法对北京宇宙线台站的地面宇宙线强度在地磁暴前后的变化特征进行分析,得到:1)在平静期,北京宇宙线数据存在准24h周期性的特征,且通过分析周期为12h的Morlet小波"模",发现值稳定,且小于0.6;2)以90天为时间窗口,对2004年7月地磁暴前后的小波频谱变化进行详细分析,发现当发生大地磁暴时,宇宙线的静日准24h周期被打破,其他周期的波动开始增强.进一步研究发现,周期12h的波动在大地磁暴数小时到1天左右会出现显著增强,这一现象在2001、2002和2004年期间的大地磁暴前得到验证.3)Morlet小波"模"数据的急速增大是发生地磁暴的先兆特征,当小波模变化达到一定的阈值就可能发生大磁暴.本文分析了周期为12h时小波的模数据,对强地磁暴事件进行统计,选定阈值0.6,并通过2003年的6次大地磁暴进行预报验证,结果表明该方法不仅能够对大地磁暴事件进行预报,而且提前量满足预报需求,为基于宇宙线实测数据预报地磁暴方法提供了重要基础.     

A multivariate study of Forbush decrease simultaneity

The distribution of the cosmic ray flux over the Earth is not uniform, but the result of complex phenomena within the Sun–Earth environment. A Forbush decrease (Fd) is a rapid decrease in the intensity of cosmic rays. A given Fd can appear in different forms at different locations of the Earth. An investigation of simultaneous observations of Fd events by a selection of cosmic ray stations remains a subject of interest among researchers and numerous methods of analysis can be found in literature. Although these studies have contributed significantly to our knowledge, the variability in the manifestations of Fds demonstrates that there are still open questions in this field. The present work suggests that multivariate analysis is a simple method that can be used to discriminate between globally simultaneous and non-simultaneous Fds.     

Index of the Long-Term Influence of Sporadic Solar Activity on Cosmic Ray Modulation

Coronal mass ejections (CMEs) not only produce Forbush effects but contribute to long-term modulations of cosmic rays. That makes coronal ejections the main sporadic manifestations of the solar activity, which should be considered in modulation models. In this paper, a new version of the CME-index is proposed based on a comparison of the data from satellite coronographs with Forbush effects and long-term variations of cosmic rays.     

耀斑引发的激波初始速度对激波到达时间预测的影响

利用Hakamada-Akasofu-Fry运动学太阳风模型模拟了1981到1985卡林顿周的48个太阳耀斑事件激发的激波到达地球的时间.结果表明,对模式输入参数之一的激波初始速度进行调整,可以使模拟结果和实际观测基本一致.通过对发生在该时期多个事件的统计分析,分别得到日球表面东、西两半球耀斑爆发对应的激波初始速度调整...     

Cosmic rays and solar wind turbulence: Peculiarities of the 23rd solar cycle

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.     

Forbush decreases and Antarctic cloud anomalies in the upper troposphere

We demonstrate evidence that past composite based studies centred around the onset of Forbush decrease (FD) events may have improperly isolated the maximal galactic cosmic ray (GCR) decrease associated with the FD events. After an adjustment of the composite to account for such shortcomings we find indications of anomalous cloud cover decreases (of around 3%) located in the upper levels of the troposphere at high southern latitudes. These cloud changes are detectable after latitudinal averaging, suggesting the possibility of a second order relationship between the rate of GCR flux and cloud cover in this region. The maximal cloud change is observed in advance of the maximal GCR decrease; this implies that if the observed cloud changes bear a causal relationship to the rate of GCR flux, then cloud properties may be sensitive to changes in GCR conditions rather than the maximal deviations themselves.     

Cosmic Rays during Forbush Effects in March 1989 and March 1991: Spectra of Variation,Anisotropy, and Variations of Geomagnetic Cutoff Rigidity

Geomagnetism and Aeronomy - Two Forbush effects that occurred during geomagnetic storms in March 1989 and March 1991 are analyzed based on ground-based measurements of cosmic rays at a global...