Mechanisms of 11-yr variations and the Forbush effects of cosmic rays in the 2-30 GeV energy region
Abstract
It is shown that the chief mechanism of the 11-yr cosmic-ray variation is the change in the diffusion coefficient, which is associated with the change in the structure of the magnetic inhomogeneities of solar wind with the solar cycle. During a period of solar minima and near solar minima, the effective size of the magnetic inhomogeneities of solar wind is greater than or comparable to the Larmor radius, whereas in the solar maximum the Larmor radius is greater than the radius of magnetic inhomogeneities. A classification of the behavior of cosmic ray intensity during perturbations of the interplanetary magnetic field intensity and solar wind velocity is carried out for 214 cases from 1965 to 1985. It is concluded that the structural change in the magnetic inhomogeneities in the shock wave and magnetic cloud cavity is the reason for the Forbush effects.
- Publication:
-
Akademiia Nauk SSSR Izvestiia Seriia Fizicheskaia
- Pub Date:
- October 1991
- Bibcode:
- 1991IzSSR..55.1946A
- Keywords:
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- Cosmic Rays;
- Forbush Decreases;
- Interplanetary Magnetic Fields;
- Larmor Radius;
- Solar Wind Velocity;
- Annual Variations;
- Diffusion Coefficient;
- Magnetic Clouds;
- Solar Cycles;
- Space Radiation