  The Sun's global meridional circulation is evident as a slow poleward flow at
its surface. This flow is observed to carry magnetic elements poleward -
producing the Sun's polar magnetic fields as a key part of the 11-year sunspot
cycle. Current theories for the sunspot cycle assume that this surface flow is
part of a circulation which sinks inward at the poles and turns equatorward at
depths below 100 Mm. Here we use the advection of the Sun's convection cells by
the meridional flow to map the flow velocity in latitude and depth. Our
measurements show the largest cells clearly moving equatorward at depths below
35 Mm - the base of the Sun's surface shear layer. This surprisingly shallow
return flow indicates the need for substantial revisions to solar/stellar
dynamo theory.
