  The faster meridional flow that preceded the solar cycle 23/24 minimum is
thought to have led to weaker polar field strengths, producing the extended
solar minimum and the unusually weak cycle 24. To determine the impact of
meridional flow variations on the sunspot cycle, we have simulated the Sun's
surface magnetic field evolution with our newly developed surface flux
transport model. We investigate three different cases: a constant average
meridional flow, the observed time-varying meridional flow, and a time-varying
meridional flow in which the observed variations from the average have been
doubled. Comparison of these simulations shows that the variations in the
meridional flow over cycle 23 have a significant impact (~20%) on the polar
fields. However, the variations produced polar fields that were stronger than
they would have been otherwise. We propose that the primary cause of the
extended cycle 23/24 minimum and weak cycle 24 was the weakness of cycle 23
itself - with fewer sunspots, there was insufficient flux to build a big cycle.
We also find that any polar counter-cells in the meridional flow (equatorward
flow at high latitudes) produce flux concentrations at mid-to-high latitudes
that are not consistent with observations.
