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We study the temporal evolution of umbral dots (UDs) using measurements fromthe CRISP imaging spectropolarimeter at the Swedish 1-m Solar Telescope. Scansof the magnetically sensitive 630 nm iron lines were performed under stableatmospheric conditions for 71 min with a cadence of 63 s. These observationsallow us to investigate the magnetic field and velocity in and around UDs at aresolution approaching 0.13". From the analysis of 339 UDs, we draw thefollowing conclusions: (1)UDs show clear hints of upflows, as predicted bymagnetohydrodynamic (MHD) simulations. By contrast, we could not findsystematic downflow signals. Only in very deep layers we detect localizeddownflows around UDs, but they do not persist in time. (2) We confirm that UDsexhibit weaker and more inclined fields than their surroundings, as reportedpreviously. However, UDs that have strong fields above 2000 G or are in thedecay phase show enhanced and more vertical fields. (3)There are enhancedfields at the migration front of UDs detached from penumbral grains, as iftheir motion were impeded by the ambient field. (4) Long-lived UDs travellonger distances with slower proper motions. Our results appear to confirm someaspects of recent numerical simulations of magnetoconvection in the umbra(e.g., the existence of upflows in UDs), but not others (e.g., the systematicweakening of the magnetic field at the position of UDs.)

Temporal Evolution of Velocity and Magnetic Field in and around Umbral Dots