  We present evidence of hitherto undiscovered global-scale oscillations in the
near-surface shear layer of the Sun. These oscillations are seen as large scale
variations of radial shear in both the zonal and meridional flows relative to
their mean values. The variations cover all or most of a visible hemisphere,
and reverse with a timescale on the order of a solar rotation. A large annual
variation in the meridional shear anomaly is understandable in terms of the
tilt of the rotation axis, but the rapid oscillations of the shear anomalies in
both zonal and the meridional directions appear to be modulated in a more
complex, not-quite annual way, although the latter are also strongly modulated
by the projected rotational axis angle. Small-scale anomalies in the
neighborhood of active regions lend support to their solar origin and physical
interpretation. These results were obtained by analyzing ring-diagram fits of
low-order modes in high-resolution Doppler data from the Helioseismic and
Magnetic Imager on the Solar Dynamics Observatory.
