Superposed Epoch Analysis of Galactic Cosmic Rays and Solar Wind based on ACE Observations During Two Recent Solar Minima

Guo, Xiaocheng; Florinski, V.; Wang, Chi; Ghanbari, Keyvan

doi:10.3847/1538-4357/abe4d2

Cited by 10 publications

(5 citation statements)

References 60 publications

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“…Guo et al. ( 2021a ) attempted to disentangle the drift and diffusive effects by performing SPE analyses with respect to both SI and SB crossings. They also studied a set of isolated HCS crossings without a nearby stream boundary.…”

Section: Galactic Cosmic Rays Perturbed By Transients In the Solar Windmentioning

confidence: 99%

Galactic Cosmic Rays Throughout the Heliosphere and in the Very Local Interstellar Medium

et al. 2022

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We review recent observations and modeling developments on the subject of galactic cosmic rays through the heliosphere and in the Very Local Interstellar Medium, emphasizing knowledge that has accumulated over the past decade. We begin by highlighting key measurements of cosmic-ray spectra by Voyager, PAMELA, and AMS and discuss advances in global models of solar modulation. Next, we survey recent works related to large-scale, long-term spatial and temporal variations of cosmic rays in different regimes of the solar wind. Then we highlight new discoveries from beyond the heliopause and link these to the short-term evolution of transients caused by solar activity. Lastly, we visit new results that yield interesting insights from a broader astrophysical perspective.

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Section: Galactic Cosmic Rays Perturbed By Transients In the Solar Windmentioning

confidence: 99%

Galactic Cosmic Rays Throughout the Heliosphere and in the Very Local Interstellar Medium

et al. 2022

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“…The results presented by Kirin et al (2020) show that a certain population of particles tends to stay bound to the shock for a certain period of time, indicating that this effect may explain the weak increase in GCR flux before the main FD decrease. Related to the compression in the frontal parts of CIRs, we also emphasize the so-called snowplow effect (e.g., Guo et al 2021), which is observed as the plasma density increase that starts even before the solar wind speed starts to rise, and which may also cause the GCR pre-CIR increase (Guo et al 2021).…”

Section: Discussionmentioning

confidence: 67%

“…In recent years, a number of studies related to RFDs were published. For example, Kumar (2014), Badruddin & Kumar (2016), Ghanbari et al (2019), and Guo et al (2021) studied the behavior of RFDs by applying the superposed epoch analysis approach. We also refer to the observation-based studies by Modzelewska et al (2020) and Shen et al (2020), as well as to the numerical studies by Alania et al (2011), Guo & Florinski (2016), Kopp et al (2017), and Luo et al (2020).…”

Section: Introductionmentioning

confidence: 99%

Analytic modeling of recurrent Forbush decreases caused by corotating interaction regions

Vršnak

Dumbović

Heber

et al. 2022

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Context. On scales of days, the galactic cosmic ray (GCR) flux is affected by coronal mass ejections and corotating interaction regions (CIRs), causing so-called Forbush decreases and recurrent Forbush decreases (RFDs), respectively. Aims. We explain the properties and behavior of RFDs recorded at about 1 au that are caused by CIRs generated by solar wind high-speed streams (HSSs) that emanate from coronal holes. Methods. We employed a convection-diffusion GCR propagation model based on the Fokker-Planck equation and applied it to solar wind and interplanetary magnetic field properties at 1 au. Results. Our analysis shows that the only two effects that are relevant for a plausible overall explanation of the observations are the enhanced convection effect caused by the increased velocity of the HSS and the reduced diffusion effect caused by the enhanced magnetic field and its fluctuations within the CIR and HSS structure. These two effects that we considered in the model are sufficient to explain not only the main signatures of RFDs, but also the sometimes observed “over-recovery” and secondary dips in RFD profiles. The explanation in terms of the convection-diffusion GCR propagation hypothesis is tested by applying our model to the observations of a long-lived CIR that recurred over 27 rotations in 2007–2008. Conclusions. Our analysis demonstrates a very good match of the model results and observations.

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“…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. In addition to analyzing GCR and plasma observations from the ACE spacecraft, Guo et al (2021) found that drift effects seem to rival diffusion and convection at 1 au during the recent solar minimum periods. It is not clear whether this is applicable to all rigidities.…”

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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Superposed Epoch Analysis of Galactic Cosmic Rays and Solar Wind based on ACE Observations During Two Recent Solar Minima

Cited by 10 publications

References 60 publications

Galactic Cosmic Rays Throughout the Heliosphere and in the Very Local Interstellar Medium

Galactic Cosmic Rays Throughout the Heliosphere and in the Very Local Interstellar Medium

Analytic modeling of recurrent Forbush decreases caused by corotating interaction regions

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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