Time variations of cosmic ray electrons and nuclei between 1978 and 2004: Evidence for charge‐dependent modulation organized by changes in solar magnetic polarity and current sheet tilt

Abstract

We have examined the 52‐day average intensities of 1.2‐GV electrons and positively charged nuclei of the same rigidity during the time period from 1978 to 2004. This time period covers a complete 22‐year solar cycle plus data from 2000 to 2004 that can be used to examine the repetitive nature of the variations. The 11‐year solar modulation changes both the electrons and nuclei intensities by similar overall factors ∼10 at 1.2 GV. Differences in the electron/nuclei modulation as exhibited by the e/nuclei ratios occur mainly between 1980–1984, 1990–1994, and 2000–2004. At these times the e/nuclei ratios increase or decrease by a factor ∼2 at 1.2 GV in close correspondence with the changes in solar magnetic polarity from positive to negative (1980) and negative to positive (1990). The e/nuclei ratio changes in 2000–2004 match those seen in 1980–1984, thus confirming the 22‐year nature of the e/nuclei variations.