Anomalous cosmic rays in the distant heliosphere and the reversal of the Sun's magnetic polarity in Cycle 23

Beginning in early June 2001 and extending over a ∼3 month period the Cosmic Ray Subsystem (CRS) experiment on Voyager 1 (80.3 AU, 34°N) observed a rapid transition in the energy of the peak intensity of anomalous cosmic ray (ACR) He from ∼11 MeV/n to ∼25 MeV/n. One month later there began a similar spectral shift at Voyager 2 (64.7 AU, 24°S). When these ACR transition times are extrapolated back from the estimated location of the heliospheric termination shock (TS) to the Sun (∼1 year) there is reasonable agreement with the range of times obtained for the polarity reversal of the interplanetary magnetic field (IPB) in the northern hemisphere near the Sun and the later reversal in the south. We interpret these changes in the ACR spectra as giving a global view of the interplanetary field reversal at the TS and confirmation of the important role of the TS in controlling the ACRs.