Influence of Magnetic Clouds on Variations of Cosmic Rays in November 2004

Yu, X. X.; Lü, Hong; Le, G.; Shi, Feng

doi:10.1007/s11207-010-9522-7

Cited by 26 publications

(9 citation statements)

References 49 publications

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“…Results presented in [ 5 ] suggested that reduced particle diffusion mainly produces the Fd in the turbulent region behind the shock. These results are supported by recent papers e.g., [ 6 , 7 , 8 , 9 ]. Data analysis presented in [ 6 ] demonstrated that the sheath region between the shock and the magnetic cloud, particularly the enhanced turbulent magnetic field, results in the scattering of cosmic-ray particles, and causes the following Fds.…”

Section: Introductionsupporting

confidence: 87%

Approximate Bayesian Computation for Estimating Parameters of Data-Consistent Forbush Decrease Model

Wawrzyńczak

Kopka

2018

Entropy

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Realistic modeling of complex physical phenomena is always quite a challenging task. The main problem usually concerns the uncertainties surrounding model input parameters, especially when not all information about a modeled phenomenon is known. In such cases, Approximate Bayesian Computation (ABC) methodology may be helpful. The ABC is based on a comparison of the model output data with the experimental data, to estimate the best set of input parameters of the particular model. In this paper, we present a framework applying the ABC methodology to estimate the parameters of the model of Forbush decrease (Fd) of the galactic cosmic ray intensity. The Fd is modeled by the numerical solution of the Fokker–Planck equation in five-dimensional space (three spatial variables, the time and particles energy). The most problematic in Fd modeling is the lack of detailed knowledge about the spatial and temporal profiles of the parameters responsible for the creation of the Fd. Among these parameters, the diffusion coefficient plays a central role. We employ the ABC Sequential Monte Carlo algorithm, scanning the space of the diffusion coefficient parameters within the region of the heliosphere where the Fd is created. Assessment of the correctness of the proposed parameters is done by comparing the model output data with the experimental data of the galactic cosmic ray intensity. The particular attention is put on the rigidity dependence of the rigidity spectrum exponent. The proposed framework is adopted to create the model of the Fd observed by the neutron monitors and ground muon telescope in November 2004.

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Section: Introductionsupporting

confidence: 87%

Approximate Bayesian Computation for Estimating Parameters of Data-Consistent Forbush Decrease Model

Wawrzyńczak

Kopka

2018

Entropy

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“…1. The CME sheath region between the CME and the shock is known to be turbulent (e.g., Manoharan et al 2000) and it is well accepted that it has a significant role to play in determining FDs (Badruddin 2002;Yu et al 2010). The isotropic perpendicular diffusion coefficient D ⊥ characterizes the penetration of cosmic rays through the ordered, compressed large-scale magnetic field near the shock, and across the ordered magnetic field of the flux rope CME.…”

Section: Perpendicular Diffusion Coefficientmentioning

confidence: 99%

High-rigidity Forbush decreases: due to CMEs or shocks?

Arunbabu

Antia

Dugad

et al. 2013

A&A

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Aims. We seek to identify the primary agents causing Forbush decreases (FDs) in high-rigidity cosmic rays observed from the Earth. In particular, we ask if these FDs are caused mainly by coronal mass ejections (CMEs) from the Sun that are directed towards the Earth, or by their associated shocks. Methods. We used the muon data at cutoff rigidities ranging from 14 to 24 GV from the GRAPES-3 tracking muon telescope to identify FD events. We selected those FD events that have a reasonably clean profile, and can be reasonably well associated with an Earth-directed CME and its associated shock. We employed two models: one that considers the CME as the sole cause of the FD (the CME-only model) and one that considers the shock as the only agent causing the FD (the shock-only model). We used an extensive set of observationally determined parameters for both models. The only free parameter in these models is the level of MHD turbulence in the sheath region, which mediates cosmic ray diffusion (into the CME for the CME-only model, and across the shock sheath for the shock-only model). Results. We find that good fits to the GRAPES-3 multi-rigidity data using the CME-only model require turbulence levels in the CME sheath region that are only slightly higher than those estimated for the quiescent solar wind. On the other hand, reasonable model fits with the shock-only model require turbulence levels in the sheath region that are an order of magnitude higher than those in the quiet solar wind. Conclusions. This observation naturally leads to the conclusion that the Earth-directed CMEs are the primary contributors to FDs observed in high-rigidity cosmic rays.

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“…Two-step FDs are in the focus of several recent studies, especially those that are associated with magnetic clouds (e.g. Yu et al 2010). They are not only the most prominent events, showing highest depression amplitudes (Cane 2000), they are also found to be useful in unrevealing the internal structure and geometry of ICMEs (e.g.…”

Section: Introductionmentioning

confidence: 99%

Cosmic ray modulation by different types of solar wind disturbances

Dumbović

Vršnak

Čalogović

et al. 2012

A&A

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Context. Solar wind disturbances such as interplanetary coronal mass ejections (ICMEs) and corotating interaction regions (CIRs) cause short-term cosmic ray depressions, generally denoted as Forbush decreases. Aims. We conduct a systematic statistical study of various aspects of Forbush decreases. The analysis provides empirical background for physical interpretations of short-term cosmic ray modulations. Methods. Firstly, we analyzed the effects of different types of solar wind disturbances, and secondly, we focused on the phenomenon of over-recovery (the return of the cosmic ray count to a value higher than the pre-decrease level). The analysis is based on groundbased neutron monitor data and the solar wind data recorded by the Advanced Composition Explorer. The correlations between various cosmic ray depressions and solar wind parameters as well as their statistical significance are analyzed in detail. In addition, we performed a normalized superposed epoch analysis for depressions and magnetic field enhancements. Results. The analysis revealed differences in the relationship between different solar wind disturbances and cosmic ray depression parameters. The amplitude of the depression for ICMEs was found to correlate well with the amplitudes of magnetic field strength and fluctuations, whereas for CIRs we found only the correlation between the amplitude of the depression and the solar wind disturbance dimension proxy vt B . Similar behavior was found for shock and no-shock events, respectively. The CIR/ICME composites show a specific behavior that is a mixture of both ICMEs and CIRs. For all analyzed categories we found that the duration of the depression correlates with the duration of the solar wind disturbance. The analysis of the over-recovery showed that there is no straightforward relationship to either "branching-effect" or geomagnetic effects, therefore we propose a scenario where the "branching-effect" is caused by several factors and is only indirectly related to the over-recovery.

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Influence of Magnetic Clouds on Variations of Cosmic Rays in November 2004

Cited by 26 publications

References 49 publications

Approximate Bayesian Computation for Estimating Parameters of Data-Consistent Forbush Decrease Model

Approximate Bayesian Computation for Estimating Parameters of Data-Consistent Forbush Decrease Model

High-rigidity Forbush decreases: due to CMEs or shocks?

Cosmic ray modulation by different types of solar wind disturbances

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