Fig. 2From: Phase space representation of neutron monitor count rate and atmospheric electric field in relation to solar activity in cycles 21 and 22Raw data and filtered signals for: the sunspot area (upper panel); the neutron monitor count rate (middle panel); the potential gradient (lower panel). The first gray-shaded area corresponds to the 1979 solar maximum, while the second gray-shaded area corresponds to the 1986 solar minimumBack to article page