REPETITIVE PATTERNS IN THE RECOVERY PHASE OF COSMIC-RAY 11-YEAR MODULATION

Emerging solar polar magnetic field regime has a significant influence on the profile, of cosmic ray 11-year modulation. Our conclusion is derived from an analysis of the shielded ion chamber data obtained at Cheltenham-Fredericksburg (1937-1974) and Yakutsk (1957-1990) and of neutron monitor data obtained at Huancayo (1953-1992), Climax (1951-1992), Ottawa (1954-1959), and Deep River (1960-1992). The recovery of cosmic ray intensity follows two distinct patterns. During odd solar activity cycles (17, 19, 2 1) when the magnetic polarity of the Sun in the northern hemisphere is negative (qA < 0) the recovery is completed in 5 to 8 years. For even cycles (18, 20) during epochs of the positive magnetic polarity in the northern hemisphere of the Sun when qA > 0 the recovery period is reduced to less than half as much. The rapid recovery seems to set in following the reversal of solar polar field during even cycles (18, 20) unless interrupted by solar activity (as for cycle 22). The delayed rapid recovery for cycle 22 is in progress. At present, it is not clear whether the next cosmic ray maximum will follow the ''mesa'' pattern.