  We perform a two-dimensional inversion of f-mode travel times to determine
near-surface solar flows. The inversion is based on optimally localized
averaging of travel times. We use finite-wavelength travel-time sensitivity
functions and a realistic model of the data errors. We find that it is possible
to obtain a spatial resolution of 2 Mm. The error in the resulting flow
estimate ultimately depends on the observation time and the number of travel
distances used in the inversion.
