The theory of cosmic-ray modulation

Quenby, J. J.

doi:10.1007/bf00226364

Cited by 42 publications

(15 citation statements)

References 118 publications

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“…See, as an example, the critical review by Cliver et al (2011). The early stages of this theoretical development, and the status of the research round that time, were reviewed by Quenby (1984). The realization also came that the only way to understand the full scope of particle drifts on galactic CR modulation was with numerical modeling.…”

Section: Charge-sign Dependent Modulationmentioning

confidence: 99%

Solar Modulation of Cosmic Rays

Potgieter

2013

Living Rev. Solar Phys.

480

377

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This is an overview of the solar modulation of cosmic rays in the heliosphere. It is a broad topic with numerous intriguing aspects so that a research framework has to be chosen to concentrate on. The review focuses on the basic paradigms and departure points without presenting advanced theoretical or observational details for which there exists a large number of comprehensive reviews. Instead, emphasis is placed on numerical modeling which has played an increasingly significant role as computational resources have become more abundant. A main theme is the progress that has been made over the years. The emphasis is on the global features of CR modulation and on the causes of the observed 11-year and 22-year cycles and charge-sign dependent modulation. Illustrative examples of some of the theoretical and observational milestones are presented, without attempting to review all details or every contribution made in this field of research. Controversial aspects are discussed where appropriate, with accompanying challenges and future prospects. The year 2012 was the centennial celebration of the discovery of cosmic rays so that several general reviews were dedicated to historical aspects so that such developments are briefly presented only in a few cases.

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Section: Charge-sign Dependent Modulationmentioning

confidence: 99%

Solar Modulation of Cosmic Rays

Potgieter

2013

Living Rev. Solar Phys.

480

377

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“…To estimate the effect of the actually existing magnetic fluctuations on the GCR intensities, we employ the following expression for the parallel mean free path ( Quenby [1984], based on Kennel and Petscheck [1966]) The magnetic rigidity, R, corresponding to gyroresonance is At constant particle rigidity, the mean free path scales as …”

Section: Evaluation Of the September 1998 Test Periodmentioning

confidence: 99%

Local and nonlocal geometry of interplanetary coronal mass ejections: Galactic cosmic ray (GCR) short‐period variations and magnetic field modeling

et al. 2008

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[1] Energetic galactic cosmic ray (GCR) particles, arriving within the solar system, are modulated by the overall interplanetary field carried in the solar wind. Localized disturbances related to solar activity cause further reduction in intensity, the largest being Forbush decreases in which fluxes can fall $20% over a few days. Understanding Forbush decreases leads to a better understanding of the magnetic field structure related to shock waves and fast streams originating at the Sun since the propagation characteristics of the GCR probe much larger regions of space than do individual spacecraft instruments. We examined the temporal history of the integral GCR fluence (!100 MeV) measured by the high-sensitivity telescope (HIST) aboard the Polar spacecraft, along with the solar wind magnetic field and plasma data from the ACE spacecraft during a 40-day period encompassing the 25 September 1998 Forbush decrease. We also examined the Forbush and (energetic storm particles) ESP event on 28 October 2003. It is the use of HIST in a highcounting-rate integral mode that allows previously poorly seen, short-scale depressions in the GCR fluxes to be observed, adding crucial information on the origin of GCR modulation. Variability on time scales within the frequency range 0.001-1.0 mHz is detected. This paper concentrates on investigating four simple models for explaining short-term reductions in the GCR intensity of both small and large amplitude. Specifically, these models are a local increase in magnetic scattering power, the passage of a shock discontinuity, and the passage of a tangential discontinuity or magnetic rope in the solar wind plasma. Analysis of the short-scale GCR depressions during a test period in September through October 1998 shows that they are not correlated with changes in magnetic scattering power or fluctuations in solar wind speed or plasma density. However, magnetic field and plasma data during the test period of Forbush decrease strongly suggest the presence of an interplanetary coronal mass ejection (ICME). Use of a non-force-free magnetic rope model in conjunction with the energetic particle data allows modeling of the geometry of the ICME in terms of a magnetic cloud topology. It is only this cloud configuration that allows a satisfactory explanation of the magnitude of the Forbush event of 25 September 1998. Calculations made during the test period point to short-scale GCR depressions being caused by either small-scale magnetic flux rope structures or possibly tangential discontinuities in the solar wind.Citation: Quenby, J. J., T. Mulligan, J. B. Blake, J. E. Mazur, and D. Shaul (2008), Local and nonlocal geometry of interplanetary coronal mass ejections: Galactic cosmic ray (GCR) short-period variations and magnetic field modeling,

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“…One class of models considers that the basic process is scattering of energetic particles by random, small-scale disturbances in the interplanetary magnetic field (see the reviews by Fisk, 1980;Rao, 1972;and Quenby, 1983). Another class of models considers that the basic motions aro drifts in the ordered large-scale magnetic field (see Joki.pii et al, 1977;Jokipii and Thomas, 1981) .…”

Section: Introductionmentioning

confidence: 99%

Interplanetary flow systems associated with cosmic ray modulation in 1977–1980

Burlaga¹,

McDonald²,

Ness³

et al. 1984

J. Geophys. Res.

150

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The hydromagnetic flog configurations assooiated with the cosmic ray modulation in 197'-1980 were determined using solar wind plasma and magnetic field data from Voyagers 1 and 2 and Helios 1. The modulation was related to two types of large-scale systems of flows: one containing a number of transients such as shocks, post-shook flows and magnetic clouds, the other consisting pr;Lmarily of a series of quasi-stationary flows following interaction regions containing a stream interface and often bounded by a forward-reverse shook pair. Each of the three major episodes of cosmic' ray modulation was characterized by the passage of a system of tra., It :lows.

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The theory of cosmic-ray modulation

Cited by 42 publications

References 118 publications

Solar Modulation of Cosmic Rays

Solar Modulation of Cosmic Rays

Local and nonlocal geometry of interplanetary coronal mass ejections: Galactic cosmic ray (GCR) short‐period variations and magnetic field modeling

Interplanetary flow systems associated with cosmic ray modulation in 1977–1980

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