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Measurements of the large cellular flows on the Sun were made by correlation tracking of supergranules seen in Dopplergrams obtained by HMI. Measurements were averaged over 34 days to produce daily maps of the vector velocities. Flows at all latitudes are in the form of vortices with helicity left-handed in the north and right-handed in the south. There are key distinctions between the low latitude and high latitudes cells. The high latitude cells (the polar vortices) have long extensions that spiral inward toward the poles, they have lifetimes of several months, rotate differentially, drift poleward at speeds approaching 2 m s−1, and have a strong equatorward momentum flux needed to maintain the Sun’s differential rotation. The low latitude cells (Rossby waves) have roughly circular shapes, lifetimes of about one month, rotate rigidly, do not drift in latitude, and do not exhibit any momentum flux. The polar vortices have a constant temporal frequency for all ℓ indicating that they are advected by differential rotation at rates representative of the base of the convection zone. The poleward motions of these vortices suggest that the meridional flow at the base of the convection zone is poleward. The polar vortices facilitate surface flux transport by transporting flux elements along their boundaries. Their association with polar faculae and polar plumes needs further investigation.

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