OBSERVING TURBULENCE WITH A MODIFIED ACOUSTIC DOPPLER CURRENT PROFILER

This paper describes hardware and software modifications to a commerci al incoherent acoustic Doppler current profiler that allow it to be us ed as a survey tool for measurement of turbulent velocity fields assoc iated with coastal flows. The unambiguous measurement of vertical velo city. which is the heart of the modified system, can be used to provid e quantitative estimates of turbulent kinetic energy E, as well as the spatial scales at which it resides and the rate epsilon at which it i s dissipated. Provided that beam velocities are recorded directly. est imates of Reynolds stresses made from paired slant beams can be correc ted fur errors due to interbeam differences in bias error. With additi on of a towed CTD, a direct measurement of buoyancy flux can be made. Although discussed here for an incoherent Doppler used in vigorous coa stal turbulence. recent advances in coded-pulse Doppler sonars should enable use of most of these techniques in the lower-signal environment of the deep ocean, if a sufficiently stable platform can be provided.