A survey of the cosmic ray diurnal variation during 1973-1979. I - Persistence of solar diurnal variation. II - Application of diffusion-convection model to diurnal anisotropy data

An analysis of data obtained with the vertical underground muon telescope at Embudo, NM shows that the solar diurnal variation in cosmic ray intensity is a persistent phenomenon over the 1973-1979 period. Assuming that the daily fluctuations in the amplitude and phase of the diurnal variation are random perturbations about the mean vector, the relative magnitude of the random component is determined. In the second part, the Diffusion-Convection model of cosmic ray transport is applied to high rigidity particles detected at the earth in order to deduce the behavior of the heliospheric transport parameters between 1973 and 1979. It is suggested that the diurnal variation observed at Embudo during 1979 may require a contribution from the charged particle drifts.