Solar-Cycle Modulation of Galactic Cosmic Rays

Perko, J. S.

doi:10.1007/978-94-009-4025-3_20

Cited by 6 publications

(8 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…where D and /i• are constants, B is the magnetic field and Bparl•r is the magnitude of the idealized Parker spiral field. Chih and Lee (1986) following Perko and Fisk (1983), showed that simple spherically symmetric models could be made to produce behavior similar to this.…”

Section: = (Bmentioning

confidence: 92%

“…Alternatively, sonhe have insisted that transient cosmicray depressions related to disturbances in the solar wind, such as corotating interaction regions (CIl:Us), accumulate to produce the observed l 1-year simspot cycle variation (e.g., Burlaga, et al, 1981). This was modelled in a spherically-symmetric model, neglecting drifts by Perko and Fisk (1983) The present paper reports the f•rst attempt at addressing these questions within a global, three-dimensional, time-dependent model. In addition to the drift effects on the large-scale cosmic-ray distribution, we can now compute the smaller-scale effects of the CIR's.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

The role of corotating interaction regions in cosmic‐ray modulation

Kóta¹,

Jokipii²

1991

Geophysical Research Letters

View full text Add to dashboard Cite

We present the first global simulations of the modulation of galactic cosmic rays by a three‐dimensional solar wind with corotating interaction regions. The cosmic‐ray transport equation is solved in a computed wind and magnetic‐field model. The results show both the previously‐neglected small‐scale response to CIR's and global, drift‐dominated, effects which are similar to previous models. Our model predicts a correlation between the local magnetic field and the rate of decrease of the cosmic‐ray intensity which is similar to that observed. This is found to be due to inhibited diffusion. We suggest that such small‐scale variations are local and that they do not change significantly the global cosmic‐ray structure except, perhaps, near sunspot maximum.

show abstract

Section: = (Bmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

The role of corotating interaction regions in cosmic‐ray modulation

Kóta¹,

Jokipii²

1991

Geophysical Research Letters

View full text Add to dashboard Cite

show abstract

“…Heliospheric transport of GCR is described by Parker's transport equation [ Parker , 1965] which can be written in a spherically symmetric and steady state form as where U ( r , T ) is the cosmic ray number density per unit interval of kinetic energy T , r is the heliocentric distance, V is the solar wind speed, α = ( T + 2 · T r )/( T + T r ), T r is proton's rest energy and κ is the diffusion coefficient. It is usual to take the diffusion coefficient in the following form [see, e.g., Perko , 1987] where β = v / c , v and P are the velocity and rigidity of a cosmic ray particle ( P b = 1 GV).…”

Section: Heliospheric Modulation Of Cosmic Raysmentioning

confidence: 99%

A physical reconstruction of cosmic ray intensity since 1610

Usoskin¹

2002

J.‐Geophys.‐Res.

143

128

View full text Add to dashboard Cite

The open solar magnetic flux has been recently reconstructed by Solanki et al. [2000, 2002] for the last 400 years from sunspot data. Using this reconstructed magnetic flux as an input to a spherically symmetric quasi‐steady state model of the heliosphere, we calculate the expected intensity of galactic cosmic rays at the Earth's orbit since 1610. This new, physical reconstruction of the long‐term cosmic ray intensity is in good agreement with the neutron monitor measurements during the last 50 years. Moreover, it resolves the problems related to previous reconstruction for the last 140 years based on linear correlations. We also calculate the flux of 2 GeV galactic protons and compare it to the cosmogenic 10Be level in polar ice in Greenland and Antarctica. An excellent agreement between the calculated and measured levels is found over the last 400 years.

show abstract

“…The energy loss suffered by CRs as they journey from the heliopause to Earth is through multiple scattering off the magnetic field of the solar wind. The average energy lost, for CRs with energies significantly larger than their rest mass, can be approximated with Δ E ≈ Rv wind /(3 A ) [ Perko , 1987], where R is the radius of the heliopause and A is a constant proportional to κ, the diffusion coefficient of CRs in the solar wind. This expression is valid only if Δ E ≪ E , E ≫ m 0 c 2 and R ≫ 1 AU .…”

Section: Solar Wind Evolution and Predicted Temperature Changementioning

confidence: 99%

Toward a solution to the early faint Sun paradox: A lower cosmic ray flux from a stronger solar wind

Shaviv

2003

J. Geophys. Res.

View full text Add to dashboard Cite

[1] Standard solar models predict a solar luminosity that gradually increased by about 30% over the past 4.5 billion years. Under the faint Sun, Earth should have been frozen solid for most of its existence. Yet, running water is observed to have been present since very early in Earth's history. This enigma is known as the faint Sun paradox. We show here that it can be partially resolved once we consider the cooling effect that cosmic rays are suspected to have on the global climate and by considering that the younger Sun must have had a stronger solar wind such that it was more effective at stopping cosmic rays from reaching Earth. The paradox can then be completely resolved with the further contribution of modest greenhouse gas warming. When we add the cosmic ray flux modulation by a variable star formation rate in the Milky Way, we recover the long-term glacial activity on Earth. As to the future, we find that the average global temperature will increase by typically 10°K in the coming 2 Gyr.

show abstract

Solar-Cycle Modulation of Galactic Cosmic Rays

Cited by 6 publications

References 21 publications

The role of corotating interaction regions in cosmic‐ray modulation

The role of corotating interaction regions in cosmic‐ray modulation

A physical reconstruction of cosmic ray intensity since 1610

Toward a solution to the early faint Sun paradox: A lower cosmic ray flux from a stronger solar wind

Contact Info

Product

Resources

About