Characteristics of recurrent Forbush decreases in Galactic cosmic ray intensity during positive and negative solar magnetic polarities

Kallaya, O.; Yeeram, T.

doi:10.1007/s10509-021-03970-2

Cited by 2 publications

(2 citation statements)

References 31 publications

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“…We found that there is no correlation between the CIR FD Amplitude and any of the following: maximum solar wind speed, solar wind speed increase, and maximum magnetic field magnitude. This agrees with Kallaya & Yeeram (2021), whose findings suggest that these correlations are weak from 2008 to 2011 (i.e., during negative solar magnetic polarity) and that there is no consistent relationship from 2015 to 2016 (i.e., during positive solar magnetic polarity). Among all of the selected solar wind parameters, we found only very weak correlations between the CIR FD Amplitude and each of the following: the maximum magnetosonic Mach number, maximum Alfvén Mach number, and Alfvén Mach number increase.The other correlations between the CIR FD Amplitude and solar wind parameters are all negligible.…”

Section: Correlation Between Fd Properties and Solar Wind Parameterssupporting

confidence: 90%

Properties of Forbush Decreases with AMS-02 Daily Proton Flux Data

Wang

Bindi

Consolandi

et al. 2023

ApJ

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A Forbush decrease (FD) is a sudden reduction of Galactic Cosmic Rays (GCRs) that is usually caused by intense solar wind transients, such as Interplanetary Coronal Mass Ejections (ICMEs) and Corotating Interaction Regions (CIRs). Using daily proton fluxes measured by AMS-02 between 2011 May and 2019 October, we identified 142 FD events with an automatic systematic analysis method. The properties of 47 FDs caused by ICMEs and of 54 FDs caused by CIRs were analyzed. We found that the rigidity dependence of the GCR flux decrease is generally better described by an exponential function for both ICME and CIR FDs. We also found that the FD Amplitude of ICME FDs has a moderate correlation with the minimum Dst index and a number of solar wind parameters, such as maximum temperature, pressure, and magnetic field. For CIR FD events, neither FD Amplitude nor Maximum Affected Rigidity had a significant correlation with solar wind parameters.

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Section: Correlation Between Fd Properties and Solar Wind Parameterssupporting

confidence: 90%

Properties of Forbush Decreases with AMS-02 Daily Proton Flux Data

Wang

Bindi

Consolandi

et al. 2023

ApJ

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“…Although it has long been known that particle drift plays a substantial role in global GCR propagation (Jokipii et al 1977;Kóta & Jokipii 1983;Potgieter & Moraal 1985), its role inside a CIR is rarely addressed and has not been properly quantified. In contrast, these effects on FDs are quantified (see, e.g., Luo et al 2017Luo et al , 2018Kallaya & Yeeram 2021). However, based on a hybrid GCR transport model with a simulated CIR structure, Guo & Florinski (2014 investigated the relative roles of diffusion and drift processes.…”

Section: Physical Processes and Cir Effectsmentioning

confidence: 99%

A Numerical Study of the Effects of a Corotating Interaction Region on Cosmic-Ray Transport. II. Features of Cosmic-Ray Composition and Rigidity

Luo,

Potgieter,

Zhang

et al. 2024

ApJ

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We continue the numerical modeling of a corotating interaction region (CIR) and the effects it has on solar-rotational recurrent variations of galactic cosmic rays (GCRs). A magnetohydrodynamic model is adapted to simulate the background solar wind plasma with a CIR structure in the inner heliosphere, which is incorporated into a comprehensive Parker-type transport model. The focus is on the simulation of the effects of a CIR on GCR protons and the two helium isotopes as a function of heliolongitude. This is to establish whether the difference in composition affects how they are modulated by the CIR in terms of their distribution in longitude. It is demonstrated that particle diffusion and drift influence the effects of the CIR with increasing rigidity from 100 MV up to 15 GV. It is found that protons and helium isotopes are modulated differently with longitude by the CIR and that particle drift influences the modulation effects in longitude. These differences dissipate with increasing rigidity. The final results are focused on the simulated amplitude of these GCR flux variations as a function of rigidity. The amplitude displays a power-law behavior above ∼1 GV with an index similar to the power index of the rigidity dependence of the assumed diffusion coefficients. The simulations further show that below this rigidity, the amplitude at first flattens off, displaying a plateau-like profile, but it then increases systematically with decreasing rigidity below ∼0.3 GV. Again, a power-law behavior is displayed, but it is completely different from that above 1 GV.

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Characteristics of recurrent Forbush decreases in Galactic cosmic ray intensity during positive and negative solar magnetic polarities

Cited by 2 publications

References 31 publications

Properties of Forbush Decreases with AMS-02 Daily Proton Flux Data

Properties of Forbush Decreases with AMS-02 Daily Proton Flux Data

A Numerical Study of the Effects of a Corotating Interaction Region on Cosmic-Ray Transport. II. Features of Cosmic-Ray Composition and Rigidity

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