East-West and Radial Anisotropy in Cosmic Ray Modulation

Authors : Rekha Agarwal MISHRA, Rajesh K. MISHRA

Pages : 187-192

View : 11 | Download : 4

Publication Date : 0000-00-00

Article Type : Research Paper

Abstract :The cosmic ray insert ignore into journalissuearticles values(CR); data observed with the Deep River neutron monitoring station has been harmonically analyzed for the period 1964--95 to obtain the diurnal and semi-diurnal components of cosmic ray intensity on geomagnetically 60 quiet days. The annual diurnal anisotropy vectors have been resolved into two components: one along the 12-Hr direction, the radial anisotropy component; and the other along 18-Hr direction, east-west anisotropy component. It is observed that when the polarity of solar poloidal magnetic field insert ignore into journalissuearticles values(SPMF); in northern hemisphere insert ignore into journalissuearticles values(NH); is positive, the radial anisotropy component increases; whereas, the east-west anisotropy component decreases. This results in shifting the diurnal anisotropy vector towards earlier hours during the positive polarity epoch. During the negative polarity epoch, the east-west anisotropy component attains its maximum and the radial anisotropy component attains its minimum, which results in shifting the anisotropy vector gradually towards later hours. For semi-diurnal anisotropy, it is found that the magnitude of the 3-Hr component is larger than the 6-Hr component during the positive polarity epoch; which results in shifting the anisotropy vector towards earlier hours, but the same does not hold good for the negative polarity epoch i.e., the magnitude of 6-Hr component is not always found to be greater than the 3-Hr component.
Keywords : Cosmic rays, diurnal, semi diurnal, anisotropy and solar poloidal magnetic field