3. Key Results

a. Zonal Flows

• The radial dependence of the anomalous zonal flow (the measured zonal velocity with respect to the ``standard'' differential rotation rate) through at least the outer 2% of the Sun (15 Mm) has remained essentially uniform at each latitude for the last five years. The torsional oscillation amplitude at each latitude is thus independent of depth and proportional to the measured surface amplitude.

• The amplitude of the torsional oscillation signal at all depths has increased regularly, and the latitudes of peak and minimum zonal flow have moved equatorward, in good agreement with both the surface measurements and global-mode inversions.

• There is a hint that the asymmetric component of the zonal flow has reversed, with relatively faster flow in the northern hemisphere during cycle minimum and in the southern hemisphere during maximum.

b. Meridional Flows

• It appears that the dominant two-cell symmetric meridional circulation seen at all depths in 1996 and 1997 has given way since 1998 to a somewhat more complex pattern, with a more extended and intense cell in the southern hemisphere, and a much weaker cell in the northern hemisphere, possibly breaking up into a small poleward cell confined to mid- to low-latitudes and a counter-cell appearing at high latitudes.

• In the years near minimum the mean meridional flow tended to remain constant or increase slightly with depth through the zone of interest. The appearance of greater complexity in the flow in recent years in the northern hemisphere has been accompanied by greater variations in the radial profile, with substantial poleward flows at greater depths (> 10 Mm) at certain latitudes, and more pronounced reverse flows at depth at higher latitudes. While the neutral line between the two hemispheric cells has remained near the equator at the surface, it has migrated to as much as 20° north latitude below about 10 Mm in the last two years.