Temporal variations in zonal flows

Abstract

With more than half a solar-cycle worth of helioseismic data now available, we revisit the question of how solar rotation rate changes with time. The bands of faster and slower than average rotation rate are found to move towards the equator at low latitudes, while at high latitudes they move towards the poles. The low latitude bands also move upwards with time, and they extend almost to the base of the convection zone. We find no significant temporal variation in the rotation rate in the tachocline region.