Vertical Kinetic Energy Observed With LADCP/CTD Systems

Away from the boundaries, vertical motion in the ocean is dominated by high-frequency internal waves, which are very closely linked to turbulence (Thurnherr et al., GRL 2015). Conveniently, there is a very large available data base of vertical kinetic energy (VKE) observations, collected with conventional LADCP/CTD systems, from many regions of the ocean. The data base includes the profiles from many WOCE and almost all CLIVAR repeat hydrography cruises, as well as from numerous process studies carried out since the 1990s. Here, observations of vertical velocity, VKE, and VKE-parameterized dissipation from several example data sets are presented. The data include profiles from dynamically active regions, where w commonly reaches several cm/s, such as overflows, gravity currents, regions of strong internal-tide generation, as well as a time series from the outflow of a sub-glacial cavity on the West Antarctic Ice Sheet. Also included is a recent meridional GO-SHIP (CLIVAR repeat hydrography) section across the Pacific along 152W, where rms vertical velocities <1cm/s are near the noise level of the instrumentation, but where a clear poleward drop of VKE across the critical latitude for semi-diurnal PSI was nevertheless observed.