Moored Turbulence Measurements using Pulse-Coherent Doppler Sonar

Abstract Upper-ocean turbulence is central to the exchanges of heat, momentum, and gasses across air/sea interface, therefore plays a large role in weather climate. Current understanding upper-ocean mixing lacking, often leading models misrepresent mixed-layer depths sea surface temperature. In part, progress has been limited due difficulty measuring from fixed moorings which can simultaneously measure fluxes stratification over long time periods. Here we introduce direct wavenumber method for Turbulent Kinetic Energy (TKE) dissipation rates, ϵ , long-enduring using pulse-coherent ADCPs. We discuss optimal programming ADCPs, robust mechanical design use on mooring maximize data return, processing techniques including phase-ambiguity unwrapping, spectral analysis, correction instrument response. The was used Salinity Processes Regional Study (SPURS) collect two year-long sets. find mooring-derived TKE rates compare favorably estimates made nearby microstructure shear probe mounted glider during its separate two-week missions (10 −8 ) ≤ −5 m 2 s −3 . Periods disagreement between platforms coincide with differences vertical temperature profiles, may indicate that barrier layers substantially modulate horizontal scales 1-10 km. also different at 12.5 m, 7 are agreement buoyancy flux periods strong nighttime convection, consistent classic boundary layer theory.