Correlation between Cosmic Ray Intensity Variations Observed by the Large Acceptance GRAPES-3 Muon Telescope and Interplanetary Magnetic Field.

The variations of the cosmic ray intensity observed at the Earth reflect the various solar activities through the variations of solar wind plasma that fills up the heliosphere. Thus, the correlation studies between cosmic ray intensity variations and the interplanetary plasma parameters, such as the solar wind speed, the direction, and the strength of interplanetary magnetic field (IMF), are expected to provide important information on the space weather near the Earth. We have observed the cosmic ray intensity with the large acceptance GRAPES-3 muon telescope, located at Ooty in south India since 2000. We have obtained interesting results concerning the diffusion coefficient of cosmic rays near the Earth from the regression analysis with the solar wind speed [Kojima et al., Phys. Rev. D 98 (2018) 022004]. In this conference, we will report the results of the regression analysis of the cosmic ray intensity variations with the IMF.