Impact of changes in the Sun's conveyor-belt on recent solar cycles

Plasma flowing poleward at the solar surface and returning equatorward near the base of the convection zone, called the meridional circulation, constitutes the Sun's conveyor-belt. Just as the Earth's great oceanic conveyor-belt carries thermal signatures that determine El Nino events, the Sun's conveyor-belt determines timing, amplitude and shape of a solar cycle in flux-transport type dynamos. In cycle 23, the Sun's surface poleward meridional flow extended all the way to the pole, while in cycle 22 it switched to equatorward near 60°. Simulations from a flux-transport dynamo model including these observed differences in meridional circulation show that the transport of dynamo-generated magnetic flux via the longer conveyor-belt, with slower return-flow in cycle 23 compared to that in cycle 22, may have caused the longer duration of cycle 23.