Interplanetary Transients and Cosmic-Ray Anisotropy |
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| Authors: | Rajesh K Mishra Rekha Agarwal Mishra |
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| Institution: | (1) Computer and I.T. Section, Tropical Forest Research Institute, Mandla Road, Jabalpur, MP, 482 021, India;(2) Department of Physics, Govt. Model Science College (Autonomous), Jabalpur, MP, 482 001, India |
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| Abstract: | Cosmic-ray intensity data recorded with the ground-based neutron monitor at Deep River have been investigated taking into
account the associated interplanetary magnetic field and solar-wind plasma data during 1981 – 1994. A large number of days
having abnormally high or low amplitudes for five or more successive days as compared to the annual average amplitude of diurnal
anisotropy have been taken as high- or low-amplitude anisotropic wave-train events. The amplitude of the diurnal anisotropy
of these events is found to increase on days with a magnetic cloud as compared to the days prior to the event, and it is found
to decrease during the later period of the event as the cloud passes the Earth. The high-speed solar-wind streams do not play
any significant role in causing these types of events. However, corotating solar-wind streams produce significant deviations
in cosmic-ray intensity during high- and low-amplitude events. The interplanetary disturbances (magnetic clouds) are also
effective in producing cosmic-ray decreases. Hα solar flares have a good positive correlation with both the amplitude and
direction of the anisotropy for high-amplitude events, while the principal magnetic storms have a good positive correlation
with both amplitude and direction of the anisotropy for low-amplitude events. The source responsible for these unusual anisotropic
wave trains in cosmic rays has been proposed. |
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| Keywords: | Magnetic fields Prominences Filaments Flares Solar-wind Magnetic cloud and cosmic-ray |
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