Profiles of diapycnal eddy diffusivity to a maximum depth of 4000 mete
rs were derived from ocean velocity and temperature microstructure dat
a obtained in conjunction with separate experiments in the Northeast P
acific and Northeast Atlantic oceans. These profiles indicate that in
the ocean interior where the internal wave field is at background inte
nsity, the diapycnal eddy diffusivity is small (on the order of 0.1 x
10(-4) meters squared per second) and independent of depth, in apparen
t contradiction with large-scale budget studies. Enhanced dissipation
is observed in regions of elevated internal wave energy, particularly
near steeply sloping boundaries (where the eddy diffusivity estimates
exceed 1 x 10(-4) meters squared per second). These results suggest th
at basin-averaged mixing rates may be dominated by processes occurring
near the ocean boundaries.