September 2013, Volume 286, Issue 2, pp 561-576,
Open Access This content is freely available online to anyone, anywhere at any time.
Date: 29 Mar 2013
Temporal Changes in the Rigidity Spectrum of Forbush Decreases Based on Neutron Monitor Data
The Forbush decrease (Fd) of the Galactic cosmic ray (GCR) intensity and disturbances in the Earth’s magnetic field generally take place simultaneously and are caused by the same phenomenon, namely a coronal mass ejection (CME) or a shock wave created after violent processes in the solar atmosphere. The magnetic cut-off rigidity of the Earth’s magnetic field changes because of the disturbances, leading to additional changes in the GCR intensity observed by neutron monitors and muon telescopes. Therefore, one may expect distortion in the temporal changes in the power-law exponent of the rigidity spectrum calculated from neutron monitor data without correcting for the changes in the cut-off rigidity of the Earth’s magnetic field. We compare temporal changes in the rigidity spectrum of Fds calculated from neutron monitor data corrected and uncorrected for the geomagnetic disturbances. We show some differences in the power-law exponent of the rigidity spectrum of Fds, particularly during large disturbances of the cut-off rigidity of the Earth’s magnetic field. However, the general features of the temporal changes in the rigidity spectrum of Fds remain valid as they were found in our previous study. Namely, at the initial phase of the Fd, the rigidity spectrum is relatively soft and it gradually becomes hard up to the time of the minimum level of the GCR intensity. Then during the recovery phase of the Fd, the rigidity spectrum gradually becomes soft. This confirms that the structural changes of the interplanetary magnetic field turbulence in the range of frequencies of 10−6 – 10−5 Hz are generally responsible for the time variations in the rigidity spectrum we found during the Fds.
Alania, M.V., Wawrzynczak, A.: 2004, Acta Phys. Pol. B 35, 1551. ADS
Dorman, L.I.: 1963, Cosmic Rays Variations and Space Exploration, Nauka, Moscow, 197.
Dorman, L.I.: 2004, Cosmic Rays in the Earth’s Atmosphere and Underground, Kluwer Academic, Dordrecht, 140. CrossRef
Dvornikov, V.M., Sdobnov, V.E., Sergeev, A.V.: 1983 In: Proc. 18th Int. Cosmic Ray Conf. 3, 249.
Dvornikov, V.M., Sdobnov, V.E.: 2002, Int. J. Geomagn. Aeron. 3, 217.
Hasselman, K., Wibberentz, G.: 1968, Z. Geophys. 34, 353.
Shalchi, A.: 2009, Nonlinear Cosmic Ray Diffusion Theories, Springer, Berlin, 180. CrossRef
Sugiura, M.: 1964, Ann. Int. Geophys. Year 35, 945.
Toptygin, I.N.: 1985, Cosmic Rays in Interplanetary Magnetic Fields, Reidel Publishing Company, Dordrecht, 81. CrossRef
Wawrzynczak, A., Alania, M.V.: 2005a, Acta Phys. Pol. B 36, 1847. ADS
- Temporal Changes in the Rigidity Spectrum of Forbush Decreases Based on Neutron Monitor Data
- Open Access
- Available under Open Access This content is freely available online to anyone, anywhere at any time.
Volume 286, Issue 2 , pp 561-576
- Cover Date
- Print ISSN
- Online ISSN
- Springer Netherlands
- Additional Links
- Forbush decrease
- Geomangetic disturbances
- Rigidity spectrum
- Author Affiliations
- 1. Institute of Math. and Physics, Siedlce University, Siedlce, Poland
- 2. Institute of Geophysics, Tbilisi State University, Tbilisi, Georgia
- 3. Institute of Computer Science, Siedlce University, Siedlce, Poland
- 4. National Centre for Nuclear Research, Świerk-Otwock, Poland
- 5. The Institute of Solar-Terrestrial Physics of Siberian Branch of RAS, P.O. Box 291, Irkutsk, Russia