  Simultaneous and continuous observations of galactic cosmic-ray electrons and
positrons from the PAMELA and AMS02 space experiments are most suitable for
numerical modeling studies of the heliospheric modulation of these particles
below 50 GeV. A well-established comprehensive three-dimensional modulation
model is applied to compute full spectra for electrons and positrons with the
purpose of reproducing the observed ratio positrons/electrons for a period
which covers the previous long and unusual deep solar minimum activity and the
recent maximum activity phase including the polarity reversal of the solar
magnetic field. For this purpose the very local interstellar spectra for these
particles were established first. Our study is focused on how the main
modulation processes, including particle drifts, and other parameters such as
the three major diffusion coefficients, had evolved, and how the corresponding
charge-sign dependent modulation had occurred subsequently. The end result of
our effort is the detailed reproduction of positron/electrons from 2006 to
2015, displaying both qualitative and quantitative agreement with the main
observed features. Particularly, we determine how much particle drifts is
needed to explain the time dependence exhibited by the observed
positron/electron during each solar activity phase, especially during the
polarity reversal phase when no well-defined magnetic polarity was found.
