COSMIC-RAYS IN THE ATMOSPHERE - NORTH-SOUTH ASYMMETRY

An analysis of the north-south asymmetry in the cosmic ray flux was ma de with data taken in the north and south polar atmosphere from 1963 t hrough 1991. For altitudes corresponding to column densities between 1 00 and 800 g/cm(2) the N-S asymmetry is near zero during the negative phase of the solar magnetic cycle (1963-1969 and 1982-1989) and is pos itive during the positive one (1972-1979). The maximum amplitude of N- S asymmetry ((up to 3%) occurs at an atmospheric depth of X = 500-600 g/cm(2) and could be caused by primaries with rigidities of more than 30-50 GV. At higher altitudes, X < 25 g/cm(2) during almost all period s an excess of particles in the northern polar hemisphere was observed . This excess is due to the presence of reentrant albedo electrons on closed magnetic field lines.