A technique to study the cosmic ray anisotropy during the days of Forbush decreases.

An analytical method is proposed for separating the world-wide component of a Forbush decrease from the pressure-corrected hourly cosmic-ray intensity data. The technique defines the exact shape of the Forbush decrease profiles. Furthermore, the data obtained after separating the Forbush decrease component from the intensity contain only the daily variation during the decrease period. When it is subjected to a harmonic analysis, it yields the amplitude and phase of the diurnal and semidiurnal anisotropy vectors during the period of the decrease.