Cosmic ray diurnal anisotropy for a solar magnetic cycle

Cosmic ray diurnal anisotropy at high primary rigidities is extended for the 1980-1987 period. The computed values of the limiting primary rigidity for the period vary over the range 30 GV to 200 GV. For the previously studied 1965-1980 period, the mean value of the amplitude of the anisotropy is 0.5 percent. The amplitude of the diurnal anisotropy for 1965 and 1986-1987 is about 20 percent smaller. Very large amplitudes of diurnal variation are observed during the 1982-1985 period, at all primary rigidities. The value of the coupled variable lambda(parallel) x G(r) found to remain constant at about 1 percent for qA less than zero solar magnetic polarity epochs, independent of the primary rigidity. Its value is significantly lower for qA greater than zero epochs.