  The published Mount Wilson Doppler-shift measurements of the solar velocity
field taken in 1967--1982 are revisited with a more accurate model, which
includes two terms representing the meridional flow and three terms
corresponding to the convective limb shift. Integration of the recomputed data
over the visible hemisphere reveals significant variability of the net radial
velocity at characteristic time scales of 0.1--10 years, with a standard
deviation of 1.4 \ms. This result is supported by independent published
observations. The implications for exoplanet detection include reduced
sensitivity of the Doppler method to Earth-like planets in the habitable zone,
and an elevated probability of false detections at periods of a few to several
years.
