Observations of cosmic ray electrons and positrons during the early stages of the A‐ magnetic polarity epoch

Abstract

As part of our ongoing investigation of the charge sign dependence in solar modulation, we measured the cosmic ray positron abundance (0.8 GeV to 4.5 GeV) and electron flux (20 MeV to 4.5 GeV) on balloon flights from Lynn Lake, Manitoba during August 2002. We find that the decrease in the positron abundance observed in 2000 persists in 2002. The low‐energy electron flux observed on a very high altitude flight (48.8 km) reconfirms the negative slope in the spectrum. We compared our data with published data from the Ulysses spacecraft. Although other explanations are possible, we propose that finite heliospheric latitude gradients in electron fluxes have appeared in the A‐ polarity epoch, whereas no latitude gradients in electrons were observed in the A+ epoch.